CN114279378A - A method and device for obtaining volume of standing timber - Google Patents
A method and device for obtaining volume of standing timber Download PDFInfo
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Abstract
The invention provides a standing timber volume acquisition method and a standing timber volume acquisition device, which comprise the following steps: acquiring a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle; and determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on the projection change model. According to the standing timber volume acquisition method and device provided by the invention, the diameters of the target standing timber at different heights are measured by utilizing the sun side projection of the trunk, and then the nondestructive measurement of the standing timber volume is completed by adopting an approximate integral calculation mode of average sectional area, so that the required tools are few, the operation is simple, the calculation is accurate, and an effective alternative method is provided for the establishment of a standing timber volume table and the standing timber volume measurement of a specific tree species.
Description
Technical Field
The invention relates to the technical field of forestry measurement, in particular to a standing timber volume acquisition method and a standing timber volume acquisition device.
Background
The trunk volume is an important index for monitoring the energy and nutrient flow of an ecological system, and the accurate standing timber volume has important significance for calculating the accumulated volume of the forest, the annual change of biomass and the like.
At present, a commonly used method for measuring volume of standing timber is a differential volume method, which is based on the principle and process that trees are felled, a trunk is divided into a plurality of sections, the diameters of the sections are measured, the volume of each section is calculated, and the volume of the whole trunk is obtained after accumulation.
However, the measurement method is complex, time-consuming and labor-consuming, and damages to forests are often not allowed.
Disclosure of Invention
Aiming at the problems in the prior art, the embodiment of the invention provides a standing timber volume acquisition method and a standing timber volume acquisition device.
The invention provides a standing timber volume acquisition method, which comprises the following steps: acquiring a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle;
and determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on a projection change model.
According to the standing timber volume acquisition method provided by the invention, the shadow length comprises a home shadow length and a penumbra length; the solar elevation angle is obtained, and the shadow length and the width of the shadow of the target standing tree under the solar elevation angle comprise:
acquiring the solar altitude angle and the penumbra length of the target standing tree;
setting a plurality of measuring positions in the home-shadow area of the target standing tree according to a preset step length, and acquiring the home-shadow width and the home-shadow length of each measuring position; the length of the ghost is the distance from each measuring position to the center position of the base of the target standing tree.
According to the standing timber volume obtaining method provided by the invention, the step of determining the timber volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on the projection change model comprises the following steps:
based on the projection change model, acquiring the projection width of each measurement position according to the solar altitude angle and the umbra width and length of each measurement position;
acquiring the ghost length difference of any two adjacent measuring positions according to the ghost lengths of any two adjacent measuring positions, wherein the ghost length difference is a zone segmentation;
according to the umbra length difference and the projection width of any two adjacent measurement positions, and in combination with the solar altitude angle, acquiring a corresponding sectional area volume between any two adjacent measurement positions;
and acquiring the volume of the target standing timber according to all the sectional volume of the zones of the target standing timber.
According to the standing timber volume acquisition method provided by the invention, the sectional timber volume corresponding to any two adjacent measurement positions is acquired according to the umbra length difference and the projection width of the any two adjacent measurement positions and by combining the solar altitude angle, and the method comprises the following steps:
respectively acquiring the corresponding cross-sectional areas of the two arbitrary adjacent measurement positions on the target standing timber according to the projection widths of the two arbitrary adjacent measurement positions;
acquiring the corresponding height difference of any two adjacent measurement positions on the target standing tree according to the umbra length difference and the solar altitude angle of any two adjacent measurement positions;
and acquiring the sectional volume of the corresponding area between any two adjacent measuring positions according to the height difference and the cross section area corresponding to each measuring position.
According to the standing timber volume acquisition method provided by the invention, the acquisition mode of the sectional timber volume further comprises the following steps:
determining a penumbra length difference between a maximum penumbra length and the penumbra length;
and acquiring the sectional volume of the area according to the projection width corresponding to the maximum umbra length and the penumbra length difference.
According to the standing timber volume obtaining method provided by the invention, before the step of determining the timber volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on the projection change model, the method further comprises the following steps:
and constructing the projection change model according to the quantity relation among the reduction of the shadow width, the length of the shadow and the solar altitude.
According to the standing timber volume acquisition method provided by the invention, the projection change model comprises any one of the following models:
the first projection variation model is:
the second projection variation model is:
z＝(ax+by)(cx+dy)+e；
the third projection variation model is:
the fourth projection variation model is:
the fifth projection variation model is:
wherein z is the reduction of the image width of the projection width of the diameter of the standing tree; x is the tangent of the solar altitude; y is the length of the self-shadow; a is a first coefficient; b is a second coefficient; c is a third coefficient; d is a fourth coefficient; e is a fifth coefficient; f is a sixth coefficient; g is a seventh coefficient; h is an eighth coefficient; i is a ninth coefficient.
The invention provides a standing timber volume acquisition device, which comprises:
the acquisition module is used for acquiring a solar altitude angle, and the shadow length and the shadow width of the target standing tree under the solar altitude angle;
and the determining module is used for determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on a projection change model.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and operable on the processor, wherein the processor implements the steps of any of the above-mentioned stumpage volume acquisition methods when executing the program.
The invention also provides a non-transitory computer-readable storage medium having stored thereon a computer program which, when executed by a processor, carries out the steps of the standing wood volume acquisition method as described in any one of the above.
According to the standing timber volume acquisition method and device provided by the invention, the diameters of the target standing timber at different heights are measured by utilizing the sun side projection of the trunk, and then the nondestructive measurement of the standing timber volume is completed by adopting an approximate integral calculation mode of average sectional area, so that the required tools are few, the operation is simple, the calculation is accurate, and an effective alternative method is provided for the establishment of a standing timber volume table and the standing timber volume measurement of a specific tree species.
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In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic flow diagram of a method for obtaining a target standing timber volume according to the present invention;
FIG. 2 is a schematic side projection measurement of a target standing tree provided by the present invention;
FIG. 3 is a schematic view of a target standing tree height measurement provided by the present invention;
FIG. 4 is a three-dimensional schematic diagram of a first projection variation model provided by the present invention;
FIG. 5 is a three-dimensional schematic diagram of a second projection variation model provided by the present invention;
FIG. 6 is a three-dimensional schematic diagram of a third projection variation model provided by the present invention;
FIG. 7 is a three-dimensional schematic diagram of a fourth projection variation model provided by the present invention;
FIG. 8 is a three-dimensional schematic diagram of a fifth projection variation model provided by the present invention;
FIG. 9 is a schematic diagram illustrating the trend of the average accuracy variation of the projection variation model under different sun elevation conditions according to the present invention;
FIG. 10 is a schematic view of a target standing wood volume acquisition device provided by the present invention;
fig. 11 is a schematic structural diagram of an electronic device provided in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that in the description of the embodiments of the present invention, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element. The terms "upper", "lower", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
At present, a commonly used standing timber volume measurement method is a differential product finding method, and the basic principle and the process are that trees are felled, a trunk is divided into a plurality of sections to measure the diameter, the timber volume of each section is calculated, and the timber volume of the whole trunk is obtained after accumulation.
Although there are many methods for measuring the diameters of the trunk at different heights without felling down the tree, the methods are not practical, such as the height-looking method; some digital and automatic measuring means, such as close-range photogrammetry, laser radar measurement and the like, also have an attempt, but are greatly influenced by the shielding of herbaceous shrubs and other woods, have high requirements on measuring environment in the woods, are difficult to identify the height of any position of a trunk of a standing tree, have large workload of post data processing and model building, and have no practical measurement popularization.
Under the background of ecological resource protection, aiming at the fact that the existing timber volume measuring method of the standing timber is complex and the standing timber volume is difficult to obtain quickly, the standing timber volume obtaining method is based on the concept of dividing and solving the timber volume of felled timber, the standing timber volume obtaining method provided by the invention overcomes the difficulty that the standing timber cannot be cut down randomly, the diameters of different heights of the target standing timber are measured by utilizing the solar side projection of a trunk, the nondestructive measurement of the standing timber volume is further completed by adopting an approximate integral solving mode of average sectional area, and the standing timber volume measuring means is supplemented and enriched.
The standing timber volume acquisition method and apparatus provided by the embodiment of the invention are described below with reference to fig. 1 to 11.
Fig. 1 is a schematic flow diagram of a method for obtaining a target standing timber volume according to the present invention, as shown in fig. 1, including but not limited to the following steps:
first, in step S1, a solar altitude is acquired, and a shade length and a shade width of the target standing tree under the solar altitude are acquired.
Since sunlight is an approximately parallel light, not an absolute point light source, but even parallel light causes shadow edge blurring due to diffraction (also referred to as "diffraction"), the solar side projection of standing trees presents two parts, one part is a shadow area where the shadow is not blurred, and the other part is a shadow area where the shadow is blurred.
The penumbra area is difficult to identify and measure due to fuzzy boundary, but the penumbra area can be identified by naked eyes and accurately measured.
Fig. 2 is a schematic diagram of lateral projection measurement of a target standing tree provided by the present invention, and as shown in fig. 2, a diameter diffraction region, i.e., a penumbra region of the target standing tree gradually increases with the increase of the height of the target standing tree. Setting the actual diameter of the target standing tree at a certain height position as DnIf the projection width of the trunk on the side of the ground is D, the projection position of the trunk on the side of the ground is DnDetermining the width of the shadow of the trunk at the height position corresponding to the measurement position in the lateral projection of the trunk on the ground as DsThe length (hereinafter, referred to as the length of the image) from the measurement position to the point a at the center of the base of the target standing tree is l, and the reduction amount of the image width of the side projection of the target standing tree due to the double-sided blurring is Δ D, where Δ D is 2 Δ r, and there are:
Dn＝Ds+ΔD；
wherein, for a certain height position of the target standing tree, DnIs the actual diameter, also the projected width of the measurement location; dsThe width of the shadow is; Δ D is the amount of reduction in aspect ratio.
Specifically, under the condition of clear weather in the non-leaf period, the solar altitude angle alpha at any moment, and the shadow length and the shadow width D of the target standing tree at the same moment are acquiredsWherein the shadow length includes a length L of the main shadow and a length L of the penumbrasThe length L of the silhouette is the distance between the point A of the center of the base of the target standing tree and the measurement position on the silhouette, and the length L of the penumbrasThe distance between the base center position A point of the target standing timber and the farthest position of the outline of the penumbra area.
Further, in step S2, based on the projection variation model, the volume of the target standing timber is determined according to the solar altitude, the shadow length and the shadow width.
Projection width D due to blurred penumbra boundarynIt is difficult to accurately measure the amount of reduction Δ D of the shadow width, the solar elevation angle α, and the length l of the home shadow, and therefore, a projection change model can be constructed based on the specific quantitative relationship before step S2.
Based on a projection change model, according to the solar altitude angle alpha, the shadow length l and the shadow width DsAnd determining the volume V of the target standing timber.
Fig. 3 is a schematic view of measuring the height of the target standing tree provided by the present invention, as shown in fig. 3, the solar height angle at a certain point at a certain time is set as α, and the height of the target standing tree is set as HsThe length of the penumbra projected by the side of the target standing tree on the horizontal ground is Ls. By a fixed height h0The length of the penumbra projected on the ground side at the same time and the same position is measured to be l0Then triangles MON and mOn form similar triangles with:
Hs/Ls＝h0/l0；
the height H of the target standing tree can be obtained by measuring the penumbra lengths of the side projections of the target standing tree and the marker posts＝Ls·h0/l0。
According to the standing timber volume acquisition method provided by the invention, the diameters of the target standing timber at different heights are measured by utilizing the sun side projection of the trunk, and then the nondestructive measurement of the standing timber volume is completed by adopting the approximate integral calculation of the average sectional area, so that the required tools are few, the operation is simple, the calculation is accurate, and an effective alternative method is provided for the establishment of a standing timber volume table and the standing timber volume measurement of a specific tree species.
Optionally, the shadow length comprises a home shadow length and a penumbra length; the solar elevation angle is obtained, and the shadow length and the width of the shadow of the target standing tree under the solar elevation angle comprise:
acquiring the solar altitude angle and the penumbra length of the target standing tree;
setting a plurality of measuring positions in the home-shadow area of the target standing tree according to a preset step length, and acquiring the home-shadow width and the home-shadow length of each measuring position; the length of the ghost is the distance from each measuring position to the center position of the base of the target standing tree.
Calculating the volume of the single wood by adopting an average cross-sectional area distinguishing and product-solving method, firstly selecting proper measuring time, measuring the penumbra length of the marker post by utilizing the marker post, calculating the tangent value tan alpha of the solar elevation angle alpha, and then measuring the penumbra length L of the target standing woodsAnd according to the length of the main image of the target standing tree, a plurality of measuring positions are arranged in the main image area of the target standing tree, the side projection of the target standing tree is divided into a plurality of sections, and the number of the sections of the side projection of the target standing tree can be obtained.
The more the number of the sections is, the higher the calculation accuracy of the volume of the target standing timber is, but the calculation complexity is also improved; and the smaller the number of the sections is, the lower the calculation accuracy of the volume of the target standing timber is, and the lower the calculation complexity is, so that the verification proves that the higher calculation accuracy can be kept and the calculation complexity can be effectively reduced under the condition that the number of the sections is 4 to 5.
Specifically, taking a sectional equal example, a preset step length j is set on the length of the tree shadow, that is, the difference of the length of the principal shadow between any two adjacent measurement positions is set, and the length l of the principal shadow is set from the point a at the center of the base as the starting point1Starting at j until lnUntil nj, the length of the umbra is l1＝j，l2＝2j，l3＝3j，…，lnThe stumpage is divided into n +1 sections in total, and the width of the ghost of the stumpage is Ds1、Ds2、Ds3、…、DsnUsing a diameter ruler to align the bottom end l of the target standing tree0The diameter is measured at the position of 0cm to obtain Ds0。
Optionally, the determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on the projection change model includes:
based on the projection change model, acquiring the projection width of each measurement position according to the solar altitude angle and the umbra width and length of each measurement position;
acquiring the ghost length difference of any two adjacent measuring positions according to the ghost lengths of any two adjacent measuring positions, wherein the ghost length difference is a zone segmentation;
according to the umbra length difference and the projection width of any two adjacent measurement positions, and in combination with the solar altitude angle, acquiring a corresponding sectional area volume between any two adjacent measurement positions;
and acquiring the volume of the target standing timber according to all the sectional volume of the zones of the target standing timber.
Optionally, the obtaining, according to the umbra length difference and the projection width of the two arbitrary adjacent measurement positions, a corresponding segmented material product between the two arbitrary adjacent measurement positions by combining the solar altitude angle includes:
respectively acquiring the corresponding cross-sectional areas of the two arbitrary adjacent measurement positions on the target standing timber according to the projection widths of the two arbitrary adjacent measurement positions;
acquiring the corresponding height difference of any two adjacent measurement positions on the target standing tree according to the umbra length difference and the solar altitude angle of any two adjacent measurement positions;
and acquiring the sectional volume of the corresponding area between any two adjacent measuring positions according to the height difference and the cross section area corresponding to each measuring position.
Optionally, the manner of obtaining the area-segmented volume further includes:
determining a penumbra length difference between a maximum penumbra length and the penumbra length;
and acquiring the sectional volume of the area according to the projection width corresponding to the maximum umbra length and the penumbra length difference.
When calculating the volume of the standing timber of the target standing timber, first, the projection change model Δ D ═ f (tan α, l) is used to calculate the length of the ghost corresponding to each measurement positionReduction of the image width by Δ D1、ΔD2、ΔD3、…、ΔDnThen, the real diameters corresponding to the measurement positions are respectively: d1＝Ds1+ΔD1、D2＝Ds2+ΔD2、D3＝Ds3+ΔD3、…、Dn＝Dsn+ΔDnTaking the wood of each section as a cylinder, calculating the section volume V of the 1 st to the n th sections by using the root of the target standing tree as a starting point by using an average section approximate product-solving formula1，V2，V3，…，Vn(ii) a Furthermore, the length of the shadow is expressed as lnThe part above the corresponding measuring position is regarded as a cone, and the sectional volume of the area corresponding to the cone is Vn+1The sectional material volume calculation formula of each sectional area is as follows:
…
wherein j is a preset step length; alpha is the same asA positive altitude angle; the standing timber volume V is the sum of the sectional timber volumes of the n +1 sectional areas; l issIs the penumbra length of the target standing tree sun projection.
Optionally, before the determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on the projection change model, the method further includes:
and constructing the projection change model according to the quantity relation among the reduction of the shadow width, the length of the shadow and the solar altitude.
In order to verify the measurement accuracy of the standing tree shadow measurement method, due to the limitation of conditions, in 2.5.2021 in southern town of Changping district in Beijing city, the longitude and latitude are (40 ° 12 '13 "N, 116 ° 5' 1" E), a ginkgo living standing tree with the chest diameter of 25cm and better stem shape is selected, standing tree volume is distinguished and actually measured by using a lifting vehicle, the value is regarded as a standing tree volume true value, and in 10 am on the day: 00 unfolding side projection measurements. In order to explore the measuring and calculating accuracy of the standing timber volume side projection measurement, the absolute error and the relative error are used for evaluating the measured value.
It can be known from observation that the amount of reduction of the image width Δ D of the lateral projection of the diameter of the ginkgo tree is related to the length of the original image l and the solar altitude angle α during measurement, and the larger the length of the original image l is, the more obvious the effect of blurring becomes, the more the amount of reduction of the image width Δ D of the lateral projection of the diameter increases with the length of the original image, so that the projection measurement of the diameter of the ginkgo tree is gradually distorted.
In order to further search the change rule of the reduction amount of the shadow width Delta D of the side projection of the standing timber under the sun, in the south town of Changpio plain district, Beijing city, Beijing, 19.4.53 'N, 116 4.59' E in 2021, 4.19.L, the longitude and latitude are measured and recorded at different times, the width of the shadow of the side projection of a polyvinyl chloride (PVC) pipe column with the diameter of 25cm and the length of 40cm is respectively set to be 1, 3, 5, 7, 9, 11 and 13 meters (meter, m) at different shadow lengths, the tangent value tan alpha of the sun height angle alpha at the moment is measured by using a standard rod at each time of measurement, and the measurement is finished within 5 minutes for reducing the measurement error. Considering 8 a.m.: the light intensity is weaker at about 00 hours, and the tangent value tan alpha of the solar altitude alpha is repeated in the morning and in the afternoon, and the measurement time is selected from 9:00 in the morning to 12:30 in the noon (the measurement is carried out once every half hour).
On the basis of acquiring the measured data, the research describes the relationship between the reduction amount Δ D of the shadow width projected from the side, the length l of the shadow and the solar altitude tangent value tan α by constructing 5 mathematical models, so as to pass the solar altitude tangent value tan α at any timeiAnd length value of arbitrary umbrajCalculating the reduction amount Delta D of the image width of the side projectionijAnd then calculating the real diameters of the target standing trees corresponding to each measuring position at different heights. The 5 mathematical models selected included: the projection transformation model comprises a first projection transformation model, a second projection transformation model, a third projection transformation model, a fourth projection transformation model and a fifth projection transformation model.
Optionally, the projection variation model comprises any one of the following models:
the first projection variation model is:
the second projection variation model is:
z＝(ax+by)(cx+dy)+e；
the third projection variation model is:
the fourth projection variation model is:
the fifth projection variation model is:
wherein z is the reduction quantity delta D of the image width of the projection width of the diameter of the standing tree; x is the tangent value tan alpha of the solar altitude angle alpha; y is the length l of the umbra; a is a first coefficient; b is a second coefficient; c is a third coefficient; d is a fourth coefficient; e is a fifth coefficient; f is a sixth coefficient; g is a seventh coefficient; h is an eighth coefficient; i is a ninth coefficient. The first coefficient a to the ninth coefficient i can be determined by fitting measured data.
When cylinders with different diameters are at different solar altitude angles, the width of the main image of the side projection at different main image lengths is actually measured, the calculated reduction amount of the main image width is used as an actual measurement value, the precision of the above 5 projection change models Δ D ═ f (tan α, l) is verified, and the precision of each measurement value is evaluated by using absolute error, relative error, average absolute error and average relative error, and the calculation formula is as follows:
Ea＝ΔDi-ΔDir；
wherein E isaIs an absolute error; erIs a relative error;
is the mean absolute error;
is the average relative error; delta DiProjecting the calculated value of the change model for the reduction of the image width of the ith measurement position; delta DirThe actual measured value of the reduction amount of the image width projected from the side; n is the total number of times of verifying and measuring the projection change model; measurement and calculation precision mu of projection change model1Is 1-Er(ii) a Average accuracy
Is composed of
Table 1 shows a statistical table of the amount of reduction in the solar width Δ D of the side projection under the conditions of different solar altitude angles and intrinsic length, which is obtained by measuring the solar projection of a PVC pipe having a diameter of 25cm under the conditions of different intrinsic lengths at different times and calculating the amount of reduction in the solar width Δ D of the side projection of the pipe body, and the statistical results are shown in table 1.
TABLE 1 statistical table of the reduction amount Δ D of the side projection width under different sun altitude and length conditions
Note: "- -" means that the tube side projection is completely blurred and cannot be measured.
Table 2 shows the reduction in shadow width Δ D, the solar altitude tangent tan α, and the shadow length l as function model tables, and the regression modeling was performed based on the diameter measurement result of the solar side projection, 5 projection change models Δ D ═ f (tan α, l) are shown in table 2, and the degree of fitting R of the 5 projection change models is shown in table 22Between 0.9907 and 0.9911, all of which are higher than 0.99, namely, the 5 projection change models all show high fitting degree and good fitting effect; the standard deviation is between 0.4460 and 0.4664, and the standard deviation is less than 0.5 cm; from the PVC pipe diameter measurement reading, the diameter judgment accuracy is generally between 0.5 and 1cm through naked eye visual measurement, so the standard deviation of the 5 projection change models conforms to the application accuracy of the standing tree diameter side projection measurement.
TABLE 2 model table of the function of the reduction Δ D of the shadow width, the tangent tan α of the sun altitude and the length l of the shadow
In order to perform more intuitive evaluation on the projection change model, considering that the vertical wood side projection is not suitable for being excessively elongated or reduced when the vertical wood product is imaged, the tangent value tan alpha of the solar elevation angle is selected to be between 0.5 and 2.0, and the length of the image is selected to be in the range of 0 to 25 m.
Fig. 4 to 8 are three-dimensional diagrams of five projection change models projected laterally as a function of the reduction Δ D of the shadow width, the solar tangent tan α and the umbra length l, where fig. 4 is a three-dimensional diagram of a first projection change model provided by the present invention, fig. 5 is a three-dimensional diagram of a second projection change model provided by the present invention, fig. 6 is a three-dimensional diagram of a third projection change model provided by the present invention, fig. 7 is a three-dimensional diagram of a fourth projection change model provided by the present invention, fig. 8 is a three-dimensional diagram of a fifth projection change model provided by the present invention, and in fig. 4 to 8, the x-axis is the solar tangent tan α and is a zero-outline; the y-axis is the length l of the home image, and the unit is m; the z-axis represents the reduction in the aspect ratio in cm. As can be seen from the three-dimensional graph, the overall difference between the 5 projection variation models is relatively small, and particularly in the range of the length l of the main image <15m, the difference between the reduction amount Δ D of the width of the side projection is small, which indicates that the 5 projection variation models can be applied to the side projection measurement of the stumpage diameter in the range of the interval.
When the length of the ghost is larger than 15m, the difference between the 5 projection change models is relatively large, which is related to the types of the models, and the evaluation of the quality needs to expand the diameter of the PVC pipe body to carry out a wider range of actual side projection tests.
When the length l of the image is 0m, the reduction amount Δ D of the width of the side projection of the 5 projection change models is close to 0 value, and the three-dimensional graph conforms to the tree image reduction reality; when the length l of the main shadow is greater than 0m, the reduction Δ D of the shadow width of the side projection increases with the increase of the solar altitude tangent value tan α, indicating that the blurring of the penumbra increases with the increase of the solar altitude. When viewed in a y-axis (length of the umbra) cross section of the three-dimensional map, that is, under the same sun altitude angle condition, the reduction amount Δ D of the shadow width of the diameter side projection of the 5 projection change models gradually increases with the increase of the length of the umbra, and the larger the length of the umbra, the more the edge of the side projection of the pipe body is blurred, which is consistent with the observation of the side projection of the pin, the building wall, and the like. In addition, the reduction amount Δ D of the projection width of the diameter side in the second projection variation model is more approximately linearly increased along with the increase of the length l of the local image, and is more practical.
The accuracy verification is performed on 5 kinds of projection variation models by using 72 times of actual measurement of cylinders, and table 3 is an accuracy verification analysis table for the projection variation model Δ D ═ f (tan α, l), and describes the actual measurement value Δ D of the reduction amount of the image width of the side projection using the cylinders with different diameters under the conditions of different solar altitude angles and different intrinsic image lengthsrAnd (5) analyzing the result of the precision of the projection change model measurement of the lateral projection.
And calculating absolute errors of the first projection change model to the fifth projection change model respectively according to the precision analysis statistics: -0.61cm to 0.87cm, -0.67cm to 0.88cm, -0.72cm to 0.75cm, -0.72cm to 0.73cm, -0.72cm to 0.72 cm; the Mean absolute error (Mean absolute error) is: 0.20cm, 0.20cm, 0.21cm, 0.21cm, 0.21 cm; the relative errors are respectively within 30.9%, 22.3%, 27.4%, 25.9% and 26.0%, and the precision distribution interval is between 72.6% and 99.6%, 77.7% and 100.0%, 72.6% and 99.6%, 74.1% and 99.8%, and 74.0% and 99.7%; the average accuracies were 92.2%, 92.6%, 92.1%, 92.1%, 92.1%, respectively. The calculation accuracy of the projection diameter is relatively good by the 5 projection change models.
Table 3 table for precision verification analysis of projection variation model Δ D ═ f (tan α, l)
Measurement and calculation precision, namely precision mu, of each projection change model at different solar altitude angles1Make statisticsAverage accuracy of quadratic polynomial on 8 different tan α conditions during 9:00 am to 12:30 pm
And (6) performing trend analysis.
Fig. 9 is a schematic diagram of a trend of average accuracy change of the projection change model under different solar altitude conditions, as shown in fig. 9, an abscissa represents a solar altitude tangent value tan α (dimensionless quantity), an ordinate represents an average accuracy (%), and 5 kinds of projection change models include: the device comprises a first projection change Model-1, a second projection change Model-2, a third projection change Model-3, a fourth projection change Model-4 and a fifth projection change Model-5.
In fig. 9, the measurement accuracy of the 5 projection change models increases with the increase of the tangent value tan α of the solar altitude angle and then decreases, the trend lines of the fourth projection change model and the fifth projection change model completely coincide, the measurement average accuracy of the 5 projection change models reaches a maximum value of about 96% at 10 am (tan α is 1.12), and then the measurement accuracy gradually decreases with the increase of tan α; from the trend line of accuracy, when tan α is between 1.1 and 1.4, the average accuracy of the projection variation model is relatively high, which indicates that the optimal condition for measuring the lateral projection diameter is reached. Therefore, the measurement accuracy under different sun elevation angle conditions is different, and the measurement of the lateral projection diameter is not facilitated due to the fact that the lateral projection is too long or too short.
Table 4 is a standing timber area segmented side projection measurement and measurement accuracy statistical table, and as shown in table 4, stand timber area measurement and calculation are performed on a single-wood ginkgo tree (with a breast diameter of 12.4cm and a tree height h of 8.4m) by using a relatively good second projection change model, tan α is 1.27 at the time of measurement, the distance between the length of the ghost is set to 1m, and the results and accuracy of the stand timber area side projection measurement are evaluated as in table 4.
TABLE 4 standing timber area subsection side projection measurement and measurement accuracy statistical table
As can be seen from Table 4, the lateral projection is utilized to measure and calculate the volume of the single-wood ginkgo biloba stumpage, and the overall accuracy can reach 93.0%. From the aspect of measuring and calculating accuracy of the region segmentation, the accuracy is reduced along with the increase of the length of the self-shadow, mainly because the reduction amount of the shadow width of the side projection is increased along with the increase of the length of the self-shadow, the tree shadow boundary is gradually blurred, and the side projection measurement of the diameter is adversely affected.
The error from the 1 st zone segment to the 4 th zone segment is relatively small, and the total absolute error of the volume of the standing timber is 0.00286m3The relative error is only 6.0%, the accuracy is 94.0%, and the error in the part is related to the roundness of the cross-sectional area shape of the stumpage (the ratio of the actual cross-sectional area to the standard circle area with the same diameter) at the side projection measurement position, in addition to the error brought by the projection change model measurement: when the cross section of the tree is in an irregular shape, the error between the measured value of the width of the main shadow projected at different time sides and the real diameter is larger, the more the roundness is (close to 1), the closer the cross section is to the theoretical circle, and the measurement error of the side projection is smaller; the smaller the roundness is, the cross section shape is not a standard circle, the larger the fluctuation of the measured value of the diameter side projection in different directions is, the larger the influence is brought to the accuracy of the diameter measurement of the side projection, in addition, the verticality of the standing tree in the measurement direction from the sun to the standing tree to the side projection also brings error influence to the diameter measurement, when the inclination of the standing tree is smaller and the included angle between the standing tree and the ground is close to 90 degrees, the smaller the error is, the larger the inclination is, and the larger the error is.
The absolute error of the measurement and calculation of the volume of the standing timber of the 5 th subsection is 0.00064m3The relative error reaches 25.4%, the accuracy of the segmentation measurement is only 74.6%, and the performance is the worst in all the segments. The method is probably caused by two reasons, namely that the reduction of the image width of the side projection of the diameter of the top end of the stumpage is large, the boundary of the side projection is relatively fuzzy, and the adverse image is brought to the reading of the diameter measured by the flesh eye shadowSounding, wherein the error of the lateral projection measurement diameter is large; secondly, the part with the length of the image above 4m cannot be measured due to complete blurring of side projection, the part can only be simply regarded as an ideal cone to measure and calculate the volume of the standing timber, the length of the fifth division section is larger and is 3.3m, the length of the fifth division section accounts for 39.3% of the total tree height, and the inclination of the top end of the standing timber is larger than that of the bottom end of the standing timber, so that the error in measuring and calculating the volume of the standing timber of the part is larger. Therefore, the side projection method is suitable for tree species which are full in trunk shape (large in shape numerical value) and relatively low in trunk height, and has relatively large errors in calculating the volume of the standing trees of the tree species which are full in trunk shape, small in shape numerical value and relatively long in trunk.
The main error of the timber volume measurement of the standing timber comes from the tip part at the tail end of the zone section, so that the standing timber volume acquisition method provided by the invention well solves the problem, the standing timber volume is obtained by measuring the side projection of the standing timber, the operation is simple, scientific and feasible, and the method can be used as an effective supplement method for measuring the timber volume of single standing timber such as street trees, landscape trees and the like.
The invention explores the side projection width reduction rule of the standing timber caused by sun non-point light sources and diffraction, establishes a projection change model of the image width reduction amount of the standing timber diameter side projection and the sun height angle and the image length, accurately calculates the width reduction amount of the diameter side projection at any sun height angle and under any image length condition, effectively eliminates the influence of side projection virtualization, reduces the real diameters of the standing timber at different heights, realizes more accurate distinguishing and product determination of the standing timber product, and realizes the lossless timber product measurement of the standing timber.
The method for measuring the volume of the standing tree by utilizing the side projection has certain limitation in practical use, has certain requirement limitation on the standing tree self, the side projection measurement environment and time, in order to improve the measurement accuracy, the fallen leaf tree species which grow vertically and have approximately round cross sections are selected as much as possible in the projection measurement, the periphery of the standing tree is open and flat, the side projection method is only suitable for being developed in winter (in the leaf-free period), and the interference of other time-saving leaves on the projection measurement is large.
The invention carries out the side projection width measurement test on the PVC pipe with the diameter of 25cm, and can also select the standard column body with larger diameter to carry out the side projection width measurement test in a wider range, thereby establishing a more accurate solar side projection width reduction variation model and laying a foundation for the solar side projection method determination of the standing timber volume.
In addition, the standing timber volume acquisition method provided by the invention can also search the variation relation between the side projection width shrinkage under different seasons and different latitude conditions, the solar elevation tangent value and the umbra length by establishing annual observation at different latitudes, thereby optimizing and improving the universality of the side projection method. In addition, in order to improve the accuracy of the side projection method, in the future, standing timber with approximate diameter and approximate height at the bottom can be searched for according to the diameter of the bottom end of the tip cone (namely the last zone segment) and the height of the tip, the measurement of the side projection of the timber volume can be carried out, the standing timber with the approximate diameter and the approximate height at the bottom can be replaced with the standing timber with relatively large error (the last zone segment), the measurement method of the side projection of the standing timber volume can be further optimized, and the measurement accuracy can be improved.
Fig. 10 is a schematic structural view of a target standing wood volume acquisition apparatus provided by the present invention, as shown in fig. 10, including but not limited to:
the acquisition module 1001 is used for acquiring a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle;
the determining module 1002 is configured to determine a volume of the target standing timber according to the solar altitude angle, the shadow length, and the home shadow width based on a projection change model.
In the operation process of the device, the obtaining module 1001 obtains a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle; the determining module 1002 determines the volume of the target standing timber according to the solar altitude, the shadow length and the shadow width based on a projection change model.
First, the acquisition module 1001 acquires the solar altitude, and the shade length and the shade width of the target standing tree under the solar altitude.
Since sunlight is an approximately parallel light, not an absolute point light source, but even parallel light causes shadow edge blurring due to diffraction (also referred to as "diffraction"), the solar side projection of standing trees presents two parts, one part is a shadow area where the shadow is not blurred, and the other part is a shadow area where the shadow is blurred.
The penumbra area is difficult to identify and measure due to fuzzy boundary, but the penumbra area can be identified by naked eyes and accurately measured.
As shown in fig. 2, the diameter diffraction zone, i.e., penumbra zone, of the target standing tree gradually increases as the height of the target standing tree increases. Setting the actual diameter of the target standing tree at a certain height position as DnIf the projection width of the trunk on the side of the ground is D, the projection position of the trunk on the side of the ground is DnDetermining the width of the shadow of the trunk at the height position corresponding to the measurement position in the lateral projection of the trunk on the ground as DsThe length (hereinafter, referred to as the length of the image) from the measurement position to the point a at the center of the base of the target standing tree is l, and the reduction amount of the image width of the side projection of the target standing tree due to the double-sided blurring is Δ D, where Δ D is 2 Δ r, and there are:
Dn＝Ds+ΔD；
wherein, for a certain height position of the target standing tree, DnIs the actual diameter, also the projected width of the measurement location; dsThe width of the shadow is; Δ D is the amount of reduction in aspect ratio.
Specifically, under the condition of clear weather in the non-leaf period, the solar altitude angle alpha at any moment, and the shadow length and the shadow width D of the target standing tree at the same moment are acquiredsWherein the shadow length includes a length L of the main shadow and a length L of the penumbrasThe length L of the silhouette is the distance between the point A of the center of the base of the target standing tree and the measurement position on the silhouette, and the length L of the penumbrasThe distance between the base center position A point of the target standing timber and the farthest position of the outline of the penumbra area.
Further, the determining module 1002 determines a volume of the target standing timber according to the solar altitude angle, the shadow length, and the home shadow width based on a projection change model.
Due to the projection width DnDifficult to measure accurately, and the reduction amount of shadow width Delta D and the height of the sunBecause a specific quantitative relationship exists between the angle alpha and the length l of the ghost, a projection change model can be constructed based on the specific quantitative relationship before the volume of the target standing timber is determined.
Based on a projection change model, according to the solar altitude angle alpha, the shadow length l and the shadow width DsAnd determining the volume V of the target standing timber.
As shown in fig. 3, let the solar altitude at a certain point at a certain time be α, and the height of the target standing tree be HsThe length of the penumbra projected by the side of the standing tree on the horizontal ground is Ls. By a fixed height h0The length of the penumbra projected on the ground side at the same time and the same position is measured to be l0Then triangles MON and mOn form similar triangles with:
Hs/Ls＝h0/l0；
the height H of the target standing tree can be obtained by measuring the penumbra lengths of the side projections of the target standing tree and the marker post respectivelys＝Ls·h0/l0。
According to the standing timber volume acquisition device provided by the invention, the diameters of the target standing timber at different heights are measured by utilizing the sun side projection of the trunk, and then the nondestructive measurement of the standing timber volume is completed by adopting an approximate integral calculation mode of average sectional area, so that the required tools are few, the operation is simple, the calculation is accurate, and an effective alternative method is provided for the establishment of a standing timber volume table and the standing timber volume measurement of a specific tree species.
It should be noted that, when specifically executed, the standing timber volume acquisition device provided in the embodiment of the present invention may be implemented based on the standing timber volume acquisition method described in any one of the above embodiments, and details of this embodiment are not described herein.
Fig. 11 is a schematic structural diagram of an electronic device provided in the present invention, and as shown in fig. 11, the electronic device may include: a processor (processor)1110, a communication Interface (Communications Interface)1120, a memory (memory)1130, and a communication bus 1140, wherein the processor 1110, the communication Interface 1120, and the memory 1130 communicate with each other via the communication bus 1140. Processor 1110 may invoke logic instructions in memory 1130 to perform a standing timber volume acquisition method comprising: acquiring a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle; and determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on a projection change model.
In addition, the logic instructions in the memory 1130 may be implemented in software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
In another aspect, the present invention also provides a computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions which, when executed by a computer, enable the computer to perform the stumpage acquisition method provided by the above methods, the method comprising: acquiring a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle; and determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on a projection change model.
In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored, the computer program being implemented by a processor to execute the stumpage volume acquisition method provided in the above embodiments, the method including: acquiring a solar altitude angle, and a shadow length and a shadow width of a target standing tree under the solar altitude angle; and determining the volume of the target standing timber according to the solar altitude angle, the shadow length and the shadow width based on a projection change model.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
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