CN106202522A - The multiplexing method of a kind of flow field integral curve and system - Google Patents

Abstract

The invention discloses a method and system for multiplexing flow field integral curves, and belongs to the technical field of flow field data analysis. The method includes: obtaining a spatial grid structure of flow field data; placing initial seed points on all grid points of the spatial grid structure, calculating an integral curve of each seed point, and storing the integral curve in a storage device; The integral curve is a trace or a streamline; when analyzing or visualizing the flow field data, the integral curve of the initial seed point seed point at the required corresponding grid point position is directly called in the storage device . The method and system pre-calculate and save enough integral curves, and in the subsequent flow field data analysis or visualization application, the required data can be quickly obtained directly according to the area space specified by the flow field analysis or visualization application. The integral curve greatly improves the processing efficiency, and is especially suitable for the analysis and visualization processing of large-scale flow field data.

Description

A method and system for multiplexing flow field integral curves

technical field

The invention relates to the technical field of flow field data analysis, in particular to a method and system for multiplexing flow field integral curves.

Background technique

Flow field is the space occupied by fluid motion. Flow field data is an important type of scientific data, which is usually defined in two-dimensional or three-dimensional space and contains at least one velocity field. The most common flow field data include ocean current data in ocean simulations, wind field data in atmospheric simulations, and so on. Many existing flow field visualization methods are based on integral curves, such as direct rendering of integral curves, source-sink query, FTLE field (finite-time Lyapunov exponent field) calculation, and some other specially designed visualization and analysis methods. In the unsteady flow field (that is, the velocity field changes with time), the most common integral curve is the trace (place a massless particle (called the initial seed point) at a certain position in the flow field, let it be in the velocity field motion, the formed trajectory is a trajectory); in a steady flow field (that is, the velocity field does not change with time), it corresponds to a streamline (the curve tangent to the velocity vector at each point in the flow field is called a flow Wire). In actual calculation, the trace and streamline are obtained by numerical integration, so they are called integral curves.

Common flow field visualization methods usually place seed points at different times and locations as needed, and calculate a large number of traces. For large flow field data, this calculation process takes a lot of time, and because the amount of calculated trace data is too large, the trace as an intermediate result is usually discarded, which causes a waste of computing resources. In order to overcome the deficiencies of the prior art, the present invention provides a method and system for multiplexing flow field integral curves.

Contents of the invention

Aiming at the defects existing in the prior art, the object of the present invention is to provide a method and system for multiplexing flow field integral curves, through which the acquisition efficiency of flow field data analysis or visualization applications can be effectively improved .

In order to achieve the above object, the technical solution adopted in the present invention is: a method for multiplexing flow field integral curves, comprising the following steps:

(1) Obtain the spatial grid structure of the flow field data;

(2) Place initial seed points on all grid points of the spatial grid structure, calculate the integral curve of each seed point, and store the integral curve in a storage device; the integral curve is a trace or a stream Wire;

(3) When analyzing or visualizing the flow field data, directly call the required integral curve of the initial seed point corresponding to the grid point position in the storage device.

Further, in a method for multiplexing flow field integral curves as described above, in step (1), the spatial grid structure is a regular grid, and when the spatial grid structure of the acquired flow field data is an irregular grid When , on the basis of the irregular grid, a regular spatial grid structure of the flow field data is constructed; the regular grid is a two-dimensional regular grid or a three-dimensional regular grid.

Further, a method for multiplexing the integral curve of the flow field as described above, in step (2), storing the integral curve in a storage device, including:

2.1) dividing the spatial region of the spatial grid structure into a plurality of subspaces;

2.2) Establish the index of each subspace, and store the integral curve corresponding to the initial seed point contained in each subspace in association with the index of the subspace in the storage device.

Further, a method for multiplexing the flow field integral curve as described above, when the spatial grid structure is a two-dimensional regular grid, storing the integral curve in a storage device includes:

1) With the whole region of the two-dimensional regular grid as the root node of the quadtree, set up the quadtree structure of the two-dimensional spatial grid, and divide the space of the two-dimensional regular grid into a plurality of two-dimensional sub-trees Space, each leaf node of the quadtree structure corresponds to a two-dimensional subspace;

2) Establish the index of each leaf node of the quadtree structure, and store the integral curve corresponding to the initial seed point corresponding to the two-dimensional subspace corresponding to each leaf node and its node index in the storage device;

When the spatial grid structure is a three-dimensional regular grid, storing the integral curve in a storage device includes:

1. using the entire area of the three-dimensional regular grid as the root node of the octree, set up the octree structure of the three-dimensional regular grid, and divide the space of the three-dimensional regular grid into multiple three-dimensional subspaces, the octree Each leaf node of the structure corresponds to a three-dimensional subspace;

②Establish the index of each leaf node in the octree structure, and store the integral curve corresponding to the initial seed point contained in the three-dimensional subspace corresponding to each leaf node and its node index in the storage device.

Furthermore, in the method for multiplexing the integral curve of the flow field as described above, in step (2), the integral curve corresponding to the initial seed point is compressed and stored in the storage device.

Further, a method for multiplexing flow field integral curves as described above divides the spatial region of the spatial grid structure into multiple subspaces, including:

a. Set the compression ratio threshold of the integral curve;

b. dividing the space grid structure for the first time to obtain several subspaces;

c. Divide each subspace into M subspaces again;

d. For each re-divided subspace, compress the integral curve corresponding to the initial seed point contained in the subspace before the division, and record the number of bytes after compression as N1. The integral curves corresponding to the initial seed points included are respectively compressed, and the sum of M compressed bytes is recorded as N2, and it is judged whether the ratio of N1 to N2 is less than or equal to the compression ratio threshold, and if so, the two-dimensional regular grid Or the space division of the three-dimensional regular grid is completed, the division result before the second division is the final division result, if not, return to step c.

Further, a method for multiplexing the integral curve of the flow field as described above, in step (3), the integral curve of the initial seed point at the corresponding position of the required corresponding grid point is directly called in the storage device, including :

3.1) determining the flow field data spatial region specified for the analysis or visualization application, and the spatial density of initial seed points placed in the spatial region;

3.2) Find the subspace intersecting with the spatial region in all subspaces of the spatial grid structure;

3.3) according to the index of the subspace intersecting with the space region, look up the integral curve associated and stored in the storage device;

3.4) Extract the corresponding integral curve from the searched integral curve according to the space density.

A multiplexing system for flow field integral curves, comprising:

The spatial grid structure acquisition module is used to acquire the spatial grid structure of the flow field data;

An integral curve calculation module, configured to place initial seed points on all grid points of the spatial grid structure, and calculate the integral curve of each seed point; the integral curve is a trace or a streamline;

An integral curve saving module, configured to store the integral curve in a storage device;

The integral curve calling module is used to directly call the required integral curve of the initial seed point corresponding to the grid point position in the storage device when analyzing or visualizing the flow field data.

Further, in the multiplexing system of flow field integral curves as described above, the integral curve preservation module includes:

a spatial grid division unit, configured to divide the spatial area of the spatial grid structure into multiple subspaces;

The curve association storage unit is used to establish the index of each subspace, and store the integral curve corresponding to the initial seed point contained in each subspace in association with the index of the subspace in the storage device.

Further, in the above-mentioned multiplexing system of flow field integral curves, when the spatial grid structure is a two-dimensional regular grid, the spatial grid division unit includes:

The first grid division subunit is used to use the entire area of the two-dimensional regular grid as the root node of the quadtree to establish a quadtree structure of the two-dimensional spatial grid, and divide the space of the two-dimensional regular grid For multiple two-dimensional subspaces, each leaf node of the quadtree structure corresponds to a two-dimensional subspace;

The curve associated storage unit includes:

The first associative storage subunit is used to establish the index of each leaf node of the quadtree structure, and store the integral curve corresponding to the initial seed point contained in the two-dimensional subspace corresponding to each leaf node and its node index in the storage equipment;

When the spatial grid structure is a three-dimensional regular grid, the spatial grid division unit includes:

The second grid division subunit is used to use the entire area of the three-dimensional regular grid as the root node of the octree to establish an octree structure of the three-dimensional regular grid, and divide the space of the three-dimensional regular grid into Multiple three-dimensional subspaces, each leaf node of the octree structure corresponds to a three-dimensional subspace;

The curve associated storage unit includes:

The second associative storage subunit is used to establish the index of each leaf node in the octree structure, and the integral curve corresponding to the initial seed point contained in the three-dimensional subspace corresponding to each leaf node is stored in association with its node index. in the storage device.

Further, in the multiplexing system of the integral curve of the flow field as described above, the integral curve preservation module further includes:

The integral curve compression unit is configured to compress the integral curve corresponding to the initial seed point and save it in the storage device.

Further, in the above-mentioned multiplexing system of flow field integral curves, the space grid division unit includes:

Dividing the subunits for the first time is used to divide the space grid structure for the first time to obtain several subspaces;

Dividing subunits again is used to divide each subspace obtained by dividing the subunits for the first time into M subspaces again;

The division result determination subunit is used to determine the number of bytes N1 after compressing the integral curve corresponding to the initial seed point contained in the subspace before division and the M subspace after division for each subspace divided again. Whether the ratio of the sum N2 of the M compressed bytes corresponding to the integral curves corresponding to the initial seed points contained in the space is less than or equal to the compression ratio threshold, if so, the two-dimensional regular grid or the three-dimensional The space division of the regular grid is completed, and the division result before the second division is the final division result. If not, enter the second division subunit.

Further, in the multiplexing system of flow field integral curves as described above, the integral curve calling module includes:

The area-to-be-analyzed determination unit is used to determine the flow field data spatial area specified by the analysis or visualization application, and the spatial density of initial seed points placed in the spatial area;

a subspace determining unit, configured to search for a subspace intersecting the spatial region in the subspace of the spatial grid structure;

An integral curve search unit, configured to search for an associated integral curve stored in a storage device according to the index of the subspace intersecting the spatial region;

An integral curve extracting unit, configured to extract a corresponding integral curve from the found integral curves according to the space density.

The beneficial effects of the present invention are: the multiplexing method and system of the flow field integral curve provided by the present invention, by pre-calculating and saving enough integral curves, in the subsequent flow field data analysis or visualization application, directly according to the flow In the area space specified by field analysis or visualization application, the integral curve of the corresponding seed point in the corresponding subspace can be quickly obtained, which greatly reduces the acquisition time of the integral curve and improves the processing efficiency, especially suitable for large-scale flow fields Data analysis and visualization.

Description of drawings

Fig. 1 is a flow chart of a method for multiplexing a flow field integral curve provided in the specific embodiment;

Fig. 2 is the flowchart of the spatial grid structure division of flow field data in the specific embodiment;

Fig. 3 is a structural block diagram of a multiplexing system of a flow field integral curve provided in the specific embodiment;

Fig. 4 is the structural block diagram of integral curve preservation module in the specific embodiment;

Fig. 5 is the structural block diagram of the spatial grid division unit in the specific embodiment;

Fig. 6 is a schematic diagram of the three-dimensional regular grid structure and the placement of initial seed points in the embodiment.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The basic idea of the method and system for multiplexing flow field integral curves provided by the present invention is to pre-calculate and store enough integral curves of the flow field data that need to be analyzed later, and to use them directly from the stored data in subsequent analysis or visualization. The required integral curve can be extracted from the data.

Fig. 1 shows a flow chart of a method for multiplexing a flow field integral curve provided in this embodiment, as can be seen from the figure, the method may mainly include the following three steps:

Step S100: Obtain the spatial grid structure of the flow field data;

For the flow field data that needs to be analyzed or visualized later, its spatial grid structure is first obtained. Generally speaking, the space defined by the flow field data is usually expressed as a two-dimensional or three-dimensional regular grid, such as a rectilinear grid, a rectangular grid, etc., and may also be a curvilinear grid. Or an unstructured grid.

In this embodiment, the spatial grid structure is a regular grid, and when the acquired spatial grid structure of the flow field data is an irregular grid, the regular space of the flow field data is constructed on the basis of the irregular grid Grid structure; the regular grid is a two-dimensional regular grid or a three-dimensional regular grid.

If the flow field data itself already has a regular grid structure, you can directly use its regular grid structure. If the grid structure of the flow field data itself is an irregular grid, as long as the space where the data itself is located is a three-dimensional space, A set of regular grids of flow field data can be constructed, and the specific construction method can adopt the existing spatial grid construction method of flow field data.

Step S200: Place initial seed points on all grid points of the spatial grid structure of the flow field data, calculate and save the integral curve of each seed point;

Place initial seed points on all grid points of the spatial grid structure of the flow field data, calculate the integral curve of each seed point, and save the integral curve in a storage device; the integral curve is a trace or a streamline .

The integral curve is the trace or streamline of the initial seed point. In an unsteady flow field (that is, the velocity field changes with time), the most common integral curve is a trace. In a steady flow field (that is, the velocity field does not change with time) ), it corresponds to the streamline. The initial seed point is to place a massless mass point at a certain position in the flow field, and let it move in the velocity field, and the trajectory formed is a trace or streamline.

In this embodiment, the trajectory of the integral curve of the densely placed initial seed points in the space defined by the flow field data should be as long as possible until the seed points go out of the defined space. The calculation method of the integral curve adopts the existing trajectory or streamline calculation method or uses the existing visualization tool to directly generate. In practical applications, when the flow field data is small, it can be calculated on a single computer. When the data When it is large, it can be calculated in parallel in a cluster environment.

In this embodiment, the way of storing the integral curves of all initial seed points in the storage device is as follows:

1) dividing the spatial region of the spatial grid structure into multiple subspaces;

2) An index of each subspace is established, and the integral curve corresponding to the initial seed point contained in each subspace is associated with the index of the subspace and stored in the storage device.

Through this storage method, when the integral curve is searched subsequently, the corresponding nodal curve can be found in the storage device only according to the index of the subspace.

For different spatial grid structures, this embodiment provides two different ways of saving integral curves. When the spatial grid structure is a two-dimensional regular grid, the specific way of storing the integral curve in the storage device is as follows:

1) With the whole region of the two-dimensional regular grid as the root node of the quadtree, set up the quadtree structure of the two-dimensional spatial grid, and divide the space of the two-dimensional regular grid into a plurality of two-dimensional sub-trees Space, each leaf node of the quadtree structure corresponds to a two-dimensional subspace;

2) Establishing the index of each leaf node of the quadtree structure, and storing the integral curve corresponding to the initial seed point contained in the two-dimensional subspace corresponding to each leaf node and its node index in a storage device.

When the spatial grid structure is a three-dimensional regular grid, the specific way of storing the integral curve in the storage device is as follows:

1. using the entire area of the three-dimensional regular grid as the root node of the octree, set up the octree structure of the three-dimensional regular grid, and divide the space of the three-dimensional regular grid into multiple three-dimensional subspaces, the octree Each leaf node of the structure corresponds to a three-dimensional subspace;

②Establish the index of each leaf node in the octree structure, and store the integral curve corresponding to the initial seed point contained in the three-dimensional subspace corresponding to each leaf node and its node index in the storage device.

Since the integral curve of the initial seed point that needs to be calculated is usually hundreds or thousands of times of the original flow field data, in order to ensure that all flow field integral curves can be stored, in this embodiment, the integral curve is stored in the storage device When , the integral curve corresponding to the initial seed point is firstly compressed, and then the compressed result is stored in association with the subspace index (or node index).

In practical applications, the specific compression method of the integral curve can be selected according to the actual situation. For example, the integral curves corresponding to the initial seed points contained in each subspace can be compressed together, or the integral curves corresponding to each initial seed point contained in the subspace can be compressed one by one, and the compressed result Merge and then compress. The specific compression algorithm can also be selected according to the needs, and the compression method that can use the parameter curve to fit the integral curve, such as Bezier curve fitting is; it can also be a compression algorithm for any floating-point number array, such as the fpzip algorithm, of course Multiple compression algorithms can also be used in combination. In order to reduce the position error of the initial seed point corresponding to the integral curve in the grid due to compression, it is generally necessary to set the upper limit of the compression error when performing curve compression.

For the division of the spatial grid structure of the flow field data, if the number of subspaces is small, the initial seed points contained in each subspace are more, the corresponding integral curves are more, and the compression effect is better when performing compression. (The number of bytes after compression is less), but when the integral curve required is called later, the decompression will be slower. In order to balance these two aspects, this embodiment also provides a division of the spatial grid structure The method is shown in Figure 2, and the process is as follows:

a. Set the compression ratio threshold of the integral curve; the compression ratio threshold is an empirical value.

b. dividing the space grid structure for the first time to obtain several subspaces;

c. Divide each subspace into M subspaces again;

d. For each re-divided subspace, compress the integral curve corresponding to the initial seed point contained in the subspace before the division, and record the number of bytes after compression as N1. The integral curves corresponding to the initial seed points included are respectively compressed, and the sum of M compressed bytes is recorded as N2, and it is judged whether the ratio of N1 to N2 is less than or equal to the compression ratio threshold, and if so, the two-dimensional regular grid Or the space division of the three-dimensional regular grid is completed, the division result before the second division is the final division result, if not, return to step c.

This method judges the number of compressed bytes of integral curves corresponding to all initial seed points contained in the space before a subspace is divided and the number of compressed integral curves corresponding to all subspaces corresponding to the subspace after division. The relationship between the ratio of the sum of the number of bytes and the set compression ratio threshold determines whether it is necessary to continue dividing the subspace.

For example, when the octree structure is used to divide the above-mentioned three-dimensional regular grid, the real three-dimensional grid space is firstly divided into 8 first subspaces, which are respectively recorded as spaces S1-S8, and then it is judged whether it is necessary to Divide the 8 first subspaces again. For example, for space S1, first divide it into S11-S18 again, compress the integral curve corresponding to the initial seed point contained in S1, and record the number of compressed bytes as T1, respectively compress S11-S18, and add up the 8 compressed bytes to get T2. If T1/T2≤compression ratio threshold T, it is determined that space S1 does not need to be divided into S11-S18.

Step S300: directly call the required integral curve in the storage device, and complete the analysis or visualization application of the flow field data.

When analyzing or visualizing the flow field data, the required integral curve of the initial seed point corresponding to the grid point position is directly called in the storage device.

In this embodiment, the specific method of directly calling the integral curve of the initial seed point at the corresponding position of the required corresponding grid point in the storage device is as follows:

1) Determine the specified flow field data spatial region for analysis or visualization application, and place the spatial density of initial seed points in the spatial region; spatial density refers to placing an initial seed point every few grid points;

2) Find the subspace intersecting with the space region in all subspaces of the spatial grid structure; the intersection of two space regions means that the two spaces have intersecting parts, and for the two-dimensional grid interval, it means that the plane regions intersect The part of , for the three-dimensional grid interval, refers to the intersecting part of the cuboid;

3) according to the index of the subspace that intersects with the space region, look up the integral curve associated and stored in the storage device;

4) Extracting a corresponding integral curve from the found integral curves according to the space density.

Of course, if the integral curve is compressed and stored in the storage device, it is necessary to first find the corresponding compressed data in the storage device according to the index of the subspace, and then extract the corresponding integral curve after decompression.

Among them, the visualization application of flow field data includes but not limited to direct rendering of integral curve, source-sink query, FTLE field (finite-time Lyapunov exponent field) calculation, and some other specially designed visualization and analysis methods.

By adopting the method provided by the invention, the acquisition efficiency of flow field data integral curves can be greatly improved, and large-scale flow field data can be processed under the condition of limited resources.

Corresponding to the method shown in FIG. 1 , this embodiment also provides a multiplexing system of flow field integral curves. As shown in FIG. 3 , the system includes a spatial grid structure acquisition module 100 and an integral curve calculation module 200 . The integral curve saving module 300 and the integral curve calling module 400 . in:

The spatial grid structure acquisition module 100 is used to acquire the spatial grid structure of the flow field data;

An integral curve calculation module 200, configured to place initial seed points on all grid points of the spatial grid structure, and calculate the integral curve of each seed point; the integral curve is a trace or a streamline;

An integral curve saving module 300, configured to store the integral curve in a storage device;

The integral curve calling module 400 is used for directly calling the required integral curve of the initial seed point corresponding to the grid point position in the storage device when analyzing or visualizing the flow field data.

In this embodiment, the integral curve saving module 300 may include a space grid division unit 310 and a curve association storage unit 320 .

A spatial grid division unit 310, configured to divide the spatial area of the spatial grid structure into a plurality of subspaces;

The curve association storage unit 320 is configured to establish an index of each subspace, and store the integral curve corresponding to the initial seed point contained in each subspace in association with the index of the subspace in the storage device.

When the spatial grid structure of the flow field data is a two-dimensional regular grid, the spatial grid division unit 310 may include a first grid division subunit 311, and the curve association storage unit 320 may include a first association storage subunit Unit 321. When the spatial grid structure is a three-dimensional regular grid, the spatial grid division unit 310 may include a second grid division subunit 312 , and the curve association storage unit 320 may include a second association storage subunit 322 . As shown in Figure 4.

The first grid division subunit 311 is used to use the entire area of the two-dimensional regular grid as the root node of the quadtree to establish a quadtree structure of the two-dimensional spatial grid, and divide the space of the two-dimensional regular grid Divided into multiple two-dimensional subspaces, each leaf node of the quadtree structure corresponds to a two-dimensional subspace;

The first associative storage subunit 321 is used to establish the index of each leaf node of the quadtree structure, and store the integral curve corresponding to the initial seed point corresponding to the two-dimensional subspace corresponding to each leaf node and its node index in in the storage device.

The second grid division subunit 312 is used to use the entire area of the three-dimensional regular grid as the root node of the octree to establish an octree structure of the three-dimensional regular grid, and divide the space of the three-dimensional regular grid For multiple three-dimensional subspaces, each leaf node of the octree structure corresponds to a three-dimensional subspace;

The second associative storage subunit 322 is used to establish the index of each leaf node in the octree structure, and store the integral curve corresponding to the initial seed point contained in the three-dimensional subspace corresponding to each leaf node in association with its node index in the storage device.

The integral curve saving module may also include an integral curve compression unit 330 .

The integral curve compression unit 330 is configured to compress the integral curve corresponding to the initial seed point and store it in the storage device.

In this embodiment, the spatial grid division unit 310 includes a primary division subunit 3101 , a second division subunit 3102 and a division result determination subunit 3103 , as shown in FIG. 5 .

The initial division subunit 3101 is used to divide the space grid structure for the first time to obtain several subspaces;

Re-dividing the sub-unit 3102, used to divide each sub-space obtained by dividing the sub-unit for the first time into M sub-spaces again;

The division result determination subunit 3103 is used to determine the number of bytes N1 after compressing the integral curve corresponding to the initial seed point contained in the subspace before division and the M after division for each subspace divided again. Whether the integral curve corresponding to the initial seed point contained in the subspace is respectively compressed and whether the ratio of the sum N2 of the M compressed bytes is less than or equal to the compression ratio threshold, if so, the two-dimensional regular grid or The space division of the three-dimensional regular grid is completed, and the division result before the second division is the final division result; if not, enter the second division subunit 3102 .

The integral curve calling module 400 may include a region to be analyzed determination unit 410 , a subspace determination unit 420 , an integral curve search unit 430 and an integral curve extraction unit 440 .

The region to be analyzed determining unit 410, configured to determine the flow field data spatial region specified by the analysis or visualization application, and place the initial seed point spatial density in the spatial region;

A subspace determining unit 420, configured to search for a subspace intersecting the spatial region in the subspace of the spatial grid structure;

An integral curve search unit 430, configured to search for an associated stored integral curve in a storage device according to the index of the subspace intersecting the spatial region;

The integral curve extraction unit 440 is configured to extract a corresponding integral curve from the found integral curves according to the spatial density.

In order to better understand the present invention, the present invention will be further described below in conjunction with specific examples.

Example

The flow field data in this embodiment is Hurricane Isabel data, and the spatial grid structure of Hurricane Isabel data is defined on a 500×500×100 three-dimensional spatial grid, as shown in FIG. 6 .

First, place initial seed points on all grid points of the three-dimensional space grid, as shown by the circle points out of the grid points in Figure 6, let these seed points move in the velocity field of Hurricane Isabel data, and calculate each Integral curve of seed points.

Afterwards, the entire 3D space area is used as the root node of the octree, the 3D space grid is divided into multiple 3D subspaces according to the octree structure, and the index of each 3D subspace is set, each of the octree structure The leaf node corresponds to a three-dimensional subspace (it can be simply regarded as a cuboid)

The integral curve corresponding to the initial seed point contained in each subspace is compressed, and the compressed data is associated with the index of the leaf node corresponding to the subspace. In this embodiment, the integral curve of about 160 GB is compressed to 8 GB, and the position error (compression error) of the seed point on each integral curve is controlled within 1 grid point.

After that, the user can start multiple analysis or visualization applications for the flow field data, and decompress and extract the required integral curve from the compressed data according to the index of the corresponding leaf node in the octree structure. For example, if there is an application that needs to calculate the FTLE field, it needs to place an initial seed point every 4 grid points in three directions, a total of 125×125×25 seed points, at this time, only need to start from the stored data Decompress and extract the integral curve of the seed point at the corresponding position and use it to calculate the subsequent FTLE field, which greatly improves the processing efficiency.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (13)

1. A method for multiplexing a flow field integral curve, comprising the following steps: (1) Obtain the spatial grid structure of the flow field data; (2) Place initial seed points on all grid points of the spatial grid structure, calculate the integral curve of each seed point, and store the integral curve in a storage device; the integral curve is a trace or a stream Wire; (3) When analyzing or visualizing the flow field data, directly call the required integral curve of the initial seed point corresponding to the grid point position in the storage device. 2. the multiplexing method of a kind of flow field integral curve according to claim 1, is characterized in that: in step (1), described spatial grid structure is regular grid, when the spatial network of the flow field data of acquisition When the grid structure is an irregular grid, a regular spatial grid structure of the flow field data is constructed on the basis of the irregular grid; the regular grid is a two-dimensional regular grid or a three-dimensional regular grid. 3. the multiplexing method of a kind of flow field integral curve according to claim 2, is characterized in that: in step (2), described integral curve is preserved in memory device, comprises: 2.1) dividing the spatial region of the spatial grid structure into a plurality of subspaces; 2.2) Establish the index of each subspace, and store the integral curve corresponding to the initial seed point contained in each subspace in association with the index of the subspace in the storage device. 4. The multiplexing method of a flow field integral curve according to claim 3, characterized in that: when the spatial grid structure is a two-dimensional regular grid, the integral curve is stored in a storage device, including : 1) With the whole region of the two-dimensional regular grid as the root node of the quadtree, set up the quadtree structure of the two-dimensional spatial grid, and divide the space of the two-dimensional regular grid into a plurality of two-dimensional sub-trees Space, each leaf node of the quadtree structure corresponds to a two-dimensional subspace; 2) Establish the index of each leaf node of the quadtree structure, and store the integral curve corresponding to the initial seed point corresponding to the two-dimensional subspace corresponding to each leaf node and its node index in the storage device; When the spatial grid structure is a three-dimensional regular grid, storing the integral curve in a storage device includes: 1. using the entire area of the three-dimensional regular grid as the root node of the octree, set up the octree structure of the three-dimensional regular grid, and divide the space of the three-dimensional regular grid into multiple three-dimensional subspaces, the octree Each leaf node of the structure corresponds to a three-dimensional subspace; ②Establish the index of each leaf node in the octree structure, and store the integral curve corresponding to the initial seed point contained in the three-dimensional subspace corresponding to each leaf node and its node index in the storage device. 5. A method for multiplexing flow field integral curves according to claim 3, characterized in that in step (2), the integral curves corresponding to the initial seed points are compressed and stored in a storage device. 6. The multiplexing method of a flow field integral curve according to claim 5, characterized in that: the spatial region of the spatial grid structure is divided into a plurality of subspaces, comprising: a. Set the compression ratio threshold of the integral curve; b. dividing the space grid structure for the first time to obtain several subspaces; c. Divide each subspace into M subspaces again; d. For each re-divided subspace, compress the integral curve corresponding to the initial seed point contained in the subspace before the division, and record the number of bytes after compression as N1. The integral curves corresponding to the initial seed points included are respectively compressed, and the sum of M compressed bytes is recorded as N2, and it is judged whether the ratio of N1 to N2 is less than or equal to the compression ratio threshold, and if so, the two-dimensional regular grid Or the space division of the three-dimensional regular grid is completed, the division result before the second division is the final division result, if not, return to step c. 7. A method for multiplexing flow field integral curves according to any one of claims 3 to 6, characterized in that: in step (3), the required corresponding grid points are directly called in the storage device to correspond to The integral curve for the initial seed point at position, consisting of: 3.1) determining the flow field data spatial region specified for the analysis or visualization application, and the spatial density of initial seed points placed in the spatial region; 3.2) Find the subspace intersecting with the spatial region in all subspaces of the spatial grid structure; 3.3) according to the index of the subspace intersecting with the space region, look up the integral curve associated and stored in the storage device; 3.4) Extract the corresponding integral curve from the searched integral curve according to the space density. 8. A multiplexing system for flow field integral curves, comprising: The spatial grid structure acquisition module is used to acquire the spatial grid structure of the flow field data; An integral curve calculation module, configured to place initial seed points on all grid points of the spatial grid structure, and calculate the integral curve of each seed point; the integral curve is a trace or a streamline; An integral curve saving module, configured to store the integral curve in a storage device; The integral curve calling module is used to directly call the required integral curve of the initial seed point corresponding to the grid point position in the storage device when analyzing or visualizing the flow field data. 9. The multiplexing system of a flow field integral curve according to claim 8, characterized in that: the integral curve preservation module comprises: a spatial grid division unit, configured to divide the spatial area of the spatial grid structure into multiple subspaces; The curve association storage unit is used to establish the index of each subspace, and store the integral curve corresponding to the initial seed point contained in each subspace in association with the index of the subspace in the storage device. 10. The multiplexing system of a flow field integral curve according to claim 9, wherein when the spatial grid structure is a two-dimensional regular grid, the spatial grid division unit includes: The first grid division subunit is used to use the entire area of the two-dimensional regular grid as the root node of the quadtree to establish a quadtree structure of the two-dimensional spatial grid, and divide the space of the two-dimensional regular grid For multiple two-dimensional subspaces, each leaf node of the quadtree structure corresponds to a two-dimensional subspace; The curve associated storage unit includes: The first associative storage subunit is used to establish the index of each leaf node of the quadtree structure, and store the integral curve corresponding to the initial seed point contained in the two-dimensional subspace corresponding to each leaf node and its node index in the storage equipment; When the spatial grid structure is a three-dimensional regular grid, the spatial grid division unit includes: The second grid division subunit is used to use the entire area of the three-dimensional regular grid as the root node of the octree to establish an octree structure of the three-dimensional regular grid, and divide the space of the three-dimensional regular grid into Multiple three-dimensional subspaces, each leaf node of the octree structure corresponds to a three-dimensional subspace; The curve associated storage unit includes: The second associative storage subunit is used to establish the index of each leaf node in the octree structure, and the integral curve corresponding to the initial seed point contained in the three-dimensional subspace corresponding to each leaf node is stored in association with its node index. in the storage device. 11. The multiplexing system of a flow field integral curve according to claim 9, wherein the integral curve preservation module further comprises: The integral curve compression unit is configured to compress the integral curve corresponding to the initial seed point and save it in the storage device. 12. The multiplexing system of a flow field integral curve according to claim 11, wherein the space grid division unit comprises: Dividing the subunits for the first time is used to divide the space grid structure for the first time to obtain several subspaces; Dividing subunits again is used to divide each subspace obtained by dividing the subunits for the first time into M subspaces again; The division result determination subunit is used to determine the number of bytes N1 after compressing the integral curve corresponding to the initial seed point contained in the subspace before division and the M subspace after division for each subspace divided again. Whether the ratio of the sum N2 of the M compressed bytes corresponding to the integral curves corresponding to the initial seed points contained in the space is less than or equal to the compression ratio threshold, if so, the two-dimensional regular grid or the three-dimensional The space division of the regular grid is completed, and the division result before the second division is the final division result. If not, enter the second division subunit. 13. A flow field integral curve multiplexing system according to any one of claims 9 to 12, characterized in that: the integral curve call module includes: The area-to-be-analyzed determination unit is used to determine the flow field data spatial area specified by the analysis or visualization application, and the spatial density of initial seed points placed in the spatial area; a subspace determining unit, configured to search for a subspace intersecting the spatial region in the subspace of the spatial grid structure; An integral curve search unit, configured to search for an associated integral curve stored in a storage device according to the index of the subspace intersecting the spatial region; An integral curve extracting unit, configured to extract a corresponding integral curve from the found integral curves according to the space density.