Remote sensing image change detection post-processing method based on multi-scale segmentation-maximum expectation
Technical Field
The invention belongs to the technical field of remote sensing image processing, and particularly relates to a remote sensing image change detection post-processing method based on multi-scale segmentation-maximum expectation.
Background
The information of the ground features on the surface of the landed ball is continuously changed by human activities, natural disasters and the like, the change information on the surface of the earth is timely and effectively acquired, and the method has important significance on environmental monitoring, urban management, disaster emergency and other aspects. Although with the rapid development of satellite and aviation remote sensing technologies, the time resolution and the spatial resolution of images are greatly improved, so that the rapid and effective acquisition of the earth surface coverage change information becomes possible. However, the detection result obtained by the conventional change detection method still has more noise, and the reliability and the detection precision of the detection result are greatly reduced. Under the background, the post-processing method for the change detection result of the remote sensing image with high resolution is provided, and has important practical significance.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a remote sensing image change detection post-processing method based on multi-scale segmentation-maximum expectation, which has strong universality and obvious effect, aiming at the defects of the prior art.
In order to solve the technical problems, the technical scheme adopted by the invention is that the method for detecting and post-processing the change of the remote sensing image based on multi-scale segmentation-maximum expectation comprises the following steps:
step a: carrying out spatial position registration on the image before landslide and the image after landslide in the landslide area, and solving to obtain a changed image, namely an initial change detection result;
step b: performing multi-scale segmentation based On the image after landslide to obtain a multi-scale segmentation image object set S, wherein the object set S comprises n objects O1 and O2 … … Oi … … On, wherein n is a natural number greater than 0; the values of i are as follows: i is more than or equal to 1 and less than or equal to n; the object O1, O2 … … Oi … … On is a collection of spectrally-characterized approximate and spatially-adjacent pixels;
step c: taking the ith object Oi in the S, carrying out spatial superposition analysis on the ith object Oi and the initial change detection result in the step a, respectively counting the number of changed pixels and unchanged pixels in the object Oi, and determining which state is large in number of pixels;
step d: the pixel attributes within the object Oi are re-refined using the most desirable algorithm, as follows: taking the state of a large number of pixels in the Oi as the state of all pixels in the object Oi;
step e: let j equal i + 1; if j is less than or equal to n, the jth object Oj in S is taken, and the step c and the step d are sequentially executed until j is greater than n;
step f: and obtaining the states of all corresponding pixels in all the objects, namely the final change detection result.
Further, when multi-scale segmentation is performed in the step b, a fractal evolution network multi-scale segmentation method is adopted.
Further, in the step a, an initial change detection result is obtained by an EM-MRF method, or an image difference method, or a ratio method, or a change vector analysis method.
The invention has the following advantages: by introducing multi-scale segmentation and a maximum expectation algorithm, various random noises are effectively removed, so that the internal consistency of a detected target or a background area is improved, and the change detection precision is obviously improved.
Drawings
FIG. 1 is an image selected for use in an embodiment of the present invention;
wherein: FIG. 1a is a front image of a landslide;
FIG. 1b is a rear image of a landslide;
FIG. 2 is a schematic view of overlay analysis in an embodiment of the present invention;
wherein: FIG. 2a is a schematic view of a stack analysis;
FIG. 2b shows the internal pixel change state at 1 and its distribution, with white pixels changed and black pixels unchanged;
FIG. 2c shows the internal pixel change state at 2 and its distribution, with white pixels changed and black pixels unchanged;
FIG. 3 is a schematic diagram illustrating the optimization results and accuracy variation at different scales according to an embodiment of the present invention;
wherein: FIG. 3a is a schematic diagram of an initial detection result obtained by the EM-MRF method;
FIG. 3b is a diagram illustrating the optimization result and the precision variation of the segmentation scale of 5;
FIG. 3c is a diagram showing the optimization result and the precision variation of the segmentation scale 10
FIG. 3d is a diagram illustrating the optimization result and the precision variation of the segmentation scale 15;
fig. 3e is a diagram illustrating the optimization result and the precision variation of the segmentation scale 20.
Detailed Description
The invention relates to a remote sensing image change detection post-processing method based on multi-scale segmentation-maximum expectation, which comprises the following steps:
step a: carrying out spatial position registration on the image before landslide and the image after landslide in the landslide area, and solving to obtain a changed image, namely an initial change detection result; as shown in fig. 1, arcmap10.0 software is respectively adopted for a landslide front image and a landslide rear image of a landslide area, and spatial position registration of the two images is realized through an Adjust tool; and obtaining an initial change detection result by an EM-MRF method, an image difference method, a ratio method or a change vector analysis method.
Step b: performing multi-scale segmentation based On the image after landslide to obtain a multi-scale segmentation image object set S, wherein the object set S comprises n objects O1 and O2 … … Oi … … On, wherein n is a natural number greater than 0; the values of i are as follows: i is more than or equal to 1 and less than or equal to n; the object O1, O2 … … Oi … … On is a collection of spectrally-characterized approximate and spatially-adjacent pixels; in this embodiment, what is implemented is: 5. scale division under 10, 15, 20, compactness and shape parameters are set to 0.8 and 0.9 respectively, taking scale 20 as an example, the division result is shown in fig. 2, 2a, 2b and 2 c;
step c: taking the ith object Oi in the S, carrying out spatial superposition analysis on the ith object Oi and the initial change detection result in the step a, respectively counting the number of changed pixels and unchanged pixels in the object Oi, and determining which state is large in number of pixels; as shown in fig. 2, 2a, 2b, and 2c, the irregular frame is a division target, and the number of black and white pixels in the division target is counted to determine which state has the larger number of pixels.
Step d: the pixel attributes within the object Oi are re-refined using the most desirable algorithm: using the pixel state with a large number in the Oi as the state of all pixels in the object Oi;
step e: let j equal i + 1; if j is less than or equal to n, the jth object Oj in S is taken, and the step c and the step d are sequentially executed until j is greater than n;
step f: and obtaining the states of all corresponding pixels in all the objects, namely the final change detection result. As shown in FIG. 3, no matter what parameter setting is selected, a relatively optimized result can be obtained, and the method is highly universal.
The results of comparing the invention of the present invention with the EM-MRF method are shown in Table 1:
TABLE 1 comparison of EM-MRF method and post-treatment method in the present invention
As can be seen from Table 1, the false detection rate, the missed detection rate and the total error rate are significantly reduced by the method of the present invention.