Geographic data dynamic self-adaptive display method for LED spherical display screen

Abstract

The invention discloses an LED spherical display screen-oriented geographic data dynamic adaptive display method, which comprises the following steps of: constructing a non-uniform grid mapping model based on LED spherical screen physical parameters (diameter, support structure cavity size and pixel row / column spacing); the method comprises the following steps: accurately mapping geographic data (converted into longitude and latitude coordinates in advance) from a longitude and latitude coordinate system to a spherical screen pixel space, and carrying out resampling adaptation on the data based on the resolution of a display; meanwhile, a quaternion rotation transformation algorithm and a dynamic mask technology are adopted, the shielding area of the supporting structure of the LED spherical screen is calculated in real time, invisible data are automatically cut in the three-dimensional rotation process, and the problems of coordinate mapping distortion, rotation tearing and shielding area adaptation delay existing in a traditional LED spherical display system are solved. According to the method, the sub-pixel-level mapping precision of the geographic data on the LED spherical screen and the self-adaptive shielding compensation response of real-time rotation are realized.

Description

Technical Field

[0001] The present invention relates to the technical fields of spherical display systems and real-time graphics processing, and particularly to a method for dynamically adapting and displaying geographic data for an LED spherical display screen. Background Art

[0002] As a breakthrough display technology, the LED spherical screen has been widely used in the fields of exhibition display, stage art, and commercial communication due to its unique spherical geometric structure and immersive visual presentation ability. However, in the process of visualizing geographic data, this technology faces the following core technical bottlenecks: First, there is no direct mapping relationship between the pixel arrangement of the spherical display unit and the geographic coordinate system, and conventional projection methods will cause non-linear geometric distortion, especially significant deformation errors in the polar regions and high-latitude regions. Second, the local display blind area of the sphere caused by the mechanical support structure results in the inability to display geographic data over the entire surface. Finally, in the dynamic rotation transformation scenario, traditional projection algorithms are difficult to achieve seamless splicing of longitude and latitude data, and at the same time, the real-time generation of dynamic clipping needs to be solved synchronously. Summary of the Invention

[0003] Object of the Invention: The present invention aims to provide a method for dynamically adapting and displaying geographic data for an LED spherical display screen that can solve the problems of non-linear geometric distortion and difficult seamless splicing in dynamic conversion.

[0004] Technical Solution: The method for dynamically adapting and displaying geographic data for an LED spherical display screen according to the present invention includes the following steps:

[0005] (1) Convert the longitude and latitude coordinates of the original geographic data into a spherical parameter space Generate an effective display area Ω based on the physical parameters of the spherical screen;

[0006] (2) According to the pixel row pitch Δθ and column pitch of the spherical screen Establish a discretized spherical grid model through a curvature compensation algorithm, and calculate the three-dimensional coordinates (x, y, z) of each pixel point;

[0007] (3) Receive a three-dimensional rotation instruction (α, β, γ), generate a rotation matrix q(t) using a quaternion interpolation algorithm, and perform real-time coordinate transformation on the spherical screen pixel array;

[0008] (4) Establish a linear mapping relationship between the UV coordinates of the spherical screen and the display resolution, and achieve data accuracy matching through resampling;

[0009] (5) Based on the pixel coordinates after rotation transformation obtained in step (3), calculate the support structure void coverage area in real time, and perform sub-pixel level data clipping operations;

[0010] (6) Render the geographical data in real time and output it to the LED spherical screen, and adopt a double-buffer rendering mechanism.

[0011] Further, in step (1), the longitude and latitude coordinates of the original geographical data are projected through spherical projection, and the longitude and latitude geographical coordinates are mapped to the sphere by using modified equidistant cylindrical projection to obtain the spherical parameter space

[0012] θ = π(1 - v)

[0013]

[0014] where θ is the polar angle, is the azimuth angle, u is the normalized coordinate in the spherical longitude direction, v is the normalized coordinate in the spherical latitude direction, and u, v ∈ [0, 1].

[0015] Further, according to the LED spherical screen diameter D and the support structure hole parameter set {d k}, the specific calculation of the polar angle θ constraint is as follows:

[0016]

[0017] where θ min is the minimum polar angle, and θ max is the maximum polar angle.

[0018] Further, the polar angle θ is corrected non-linearly to obtain the corrected polar angle θ comp as

[0019] θ comp = θ + k·sin(2θ)

[0020] k ∈ [0.1, 0.3].

[0021] Further, for coordinate quantization, according to Δθ and the continuous space is discretized into grids,

[0022]

[0023] Further, in step (2), the curvature compensation coefficient ξ is

[0024]

[0025] Non-uniform grid generation, the number of pixels per layer is

[0026]

[0027] Calculate the three-dimensional coordinates of each discrete grid point :

[0028]

[0029] Further, before calculating the three-dimensional coordinates, perform dynamic compensation to obtain

[0030]

[0031] wherein, is the equatorial reference interval;

[0032] According to the occlusion range of the support structure, perform adaptive division and dynamically adjust Δθ as follows:

[0033]

[0034] Introduce a quadratic curvature compensation term to correct the edge distortion of the spherical surface, eliminate the edge stretching caused by spherical mapping, and make the shapes of edge regions such as Antarctica closer to the true projection. The corrected polar angle θ 矫正 is

[0035] θ 矫正 = θ + k·θ 2

[0036] k is the distortion coefficient obtained by actual measurement.

[0037] Further, step (3) is specifically as follows:

[0038] Calculate the unit quaternion q according to the three-dimensional rotation instruction (α, β, γ) as

[0039]

[0040] Adopt an interpolation algorithm, use a Squad curve to transition key frames to achieve smooth rotation, and obtain the rotation matrix q(t) as

[0041]

[0042] Perform pixel-by-pixel transformation to obtain the transformed coordinate P' as

[0043]

[0044] wherein, P = [0, x, y, z] is the extended quaternion coordinate.

[0045] Further, the linear mapping matrix M between the spherical screen UV coordinates and the display resolution in step (4) proj is

[0046]

[0047] wherein, W×H is the physical display resolution;

[0048] Bilinear interpolation is used to compensate for discretization errors and align sub-pixel I out (i,j):

[0049]

[0050] where ω m (Δu) is the horizontal weight function (linear interpolation), ω m (Δv) is the vertical weight function (linear interpolation), Δu is the sub-pixel offset in the horizontal direction, Δv is the sub-pixel offset in the vertical direction, and I in is the discrete pixel value of the input image.

[0051] Furthermore, in step (5), calculating the void coverage area of the support structure is

[0052]

[0053] where a lm is the coefficient fitted according to the shape of the support structure, is the spherical harmonic basis function, an orthonormal and complete family of spherical functions, and l is the expansion order.

[0054] Advantageous effects: Compared with the prior art, the significant advantages of the present invention are as follows: 1. The present invention adopts modified equidistant projection to weaken the deformation of the polar earth and solves the problem that conventional projection methods will cause non-linear geometric distortion, especially significant deformation errors in the polar region and high-latitude regions; 2. The present invention adopts real-time data clipping to ensure correct spherical display and solves the problem that the mechanical support structure causes local display blind areas of the sphere, resulting in the inability to achieve full-surface coverage display of geographical data; 3. The present invention adopts real-time spherical rotation calculation in the dynamic rotation transformation scenario and solves the problem that it is difficult for traditional projection algorithms to achieve seamless splicing of longitude and latitude data, and at the same time, the problem of real-time generation of dynamic clipping needs to be solved synchronously. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is the schematic diagram of the principle of the present invention;

[0056] Figure 2 is the schematic diagram of real-time clipping of the effective display area of the LED spherical screen;

[0057] Figure 3 is the comparison schematic diagram of conventional projection and modified equidistant cylindrical projection in the polar region;

[0058] Figure 4 is the comparison schematic diagram of the direct rotation of geographical data and the effect of real-time spherical rotation;

[0059] Figure 5 is the flowchart of the present invention. Detailed implementation manners

[0060] The following further describes the present invention with reference to the accompanying drawings.

[0061] The method for dynamically adapting and displaying geographic data for an LED spherical display screen according to the present invention includes the following steps:

[0062] S1. Convert the longitude and latitude coordinates of the original geographic data (if it is not longitude and latitude coordinates, it is necessary to first perform geographic data projection conversion) into a spherical parameter space Based on the physical parameters of the spherical screen (diameter D, set of support structure hole parameters {d k}, where K is the hole serial number), generate an effective display area Ω.

[0063] Preprocess the original data, check whether the original data is in the WGS84 coordinate system (EPSG:4326), and call the GDAL library to execute the gdalwarp projection conversion for non-longitude and latitude data. Perform extreme value filtering on the converted data, and perform hard truncation on the latitude θ ∈ [-90°, 90°] to prevent invalid values from being passed in.

[0064] According to the specific parameters of the LED spherical screen, the spherical screen diameter D, the set of support structure hole parameters {d k}, where K is the hole serial number, and the geometric constraint formula:

[0065]

[0066] Determine the polar angle range (latitude range) of the actual displayable area, and exclude the mechanical structure occlusion area. When displaying, the geographic data can be cropped in real time according to the mechanical structure occlusion, so that the data displayed on the LED spherical screen coincides with the real earth, as Figure 2 shown.

[0067] Use the modified equidistant cylindrical projection:

[0068]

[0069] Map the geographic data with longitude and latitude coordinates to the spherical surface.

[0070] Through the non-linear correction term:

[0071] θ comp = θ + k·sin(2θ)

[0072] k ∈ [0.1, 0.3]

[0073] As Figure 3As shown, it alleviates the compression distortion of traditional equidistant projection in the polar regions. In the left figure, the grid in the central region (corresponding to the polar region of the Earth) is very dense, showing an obvious congestion phenomenon, while in the right figure, the grid distribution in the central region is relatively more uniform, and the compression phenomenon is alleviated. At the same time, in the corrected projection (right figure), the latitudinal interval near the center is relatively larger, indicating that the deformation in the polar region has been improved.

[0074] Finally, according to the spherical coordinate system and the spherical parameters of the LED, the geographical data is discretely quantized onto the spherical screen, that is, a one-to-one matching mapping relationship between the LED beads and the geographical data is established. The grid division rules are as follows:

[0075]

[0076] Δθ and are the pixel spacings of the polar angle and the azimuth angle respectively.

[0077] S2. According to the pixel row spacing Δθ and column spacing of the spherical screen, a discretized spherical grid model is established through the curvature compensation algorithm, and the three-dimensional coordinates (x, y, z) of each pixel point are calculated.

[0078] If the LED beads are installed at equal angles, the bead density per unit area in the polar region is cosθ times that at the equator (for example, when θ = 60°, the density doubles). When displaying geographical data, Greenland (high latitude) will appear larger than its actual area, and Africa (near the equator) will be compressed. Therefore, it is necessary to dynamically adjust the density so that the actual arc length covered by each pixel is equal:

[0079]

[0080] is the equatorial reference interval

[0081] For each discrete grid point Calculate the three-dimensional coordinates according to the compensated interval:

[0082]

[0083] Among them, is the discretized spherical coordinate, which can convert the abstract longitude and latitude into an accurate position in physical space, providing a geometric reference for subsequent pixel rendering.

[0084] At this step, the following operations can be selected to increase the calculation performance and optimize the display effect:

[0085] (1) When generating the discretized grid, adaptive division is required. According to the occlusion range of the support structure, dynamically adjust the distribution density of Δθ:

[0086]

[0087] (2) Perform edge distortion correction on the spherical surface, introduce a quadratic curvature compensation term to eliminate the edge stretching caused by spherical mapping, and make the shapes of edge regions such as Antarctica closer to the true projection:

[0088] θ 矫正 = θ + k·θ 2

[0089] k is the measured distortion coefficient.

[0090] S3. Receive the three-dimensional rotation instruction (α, β, γ), generate the rotation matrix q(t) using the quaternion interpolation algorithm, and perform real-time coordinate transformation on the spherical screen pixel array.

[0091] Construct a quaternion rotation engine to generate the unit quaternion according to the received Euler angles (α, β, γ):

[0092]

[0093] Use the Squad curve to smoothly transition key frames:

[0094]

[0095] Achieve continuous transition of angular velocity between key frames q0 and q1 to avoid Euler angle deadlocks.

[0096] Perform real-time coordinate transformation. First, apply per-pixel transformation to each grid point P = (x, y, z):

[0097]

[0098] where P = [0, x, y, z] is the extended quaternion coordinate.

[0099] When the rotational angular velocity ω is known, exponential mapping can be used for acceleration:

[0100]

[0101] During display, it can ensure the correct rotation of the spherical surface of geographical data, rather than simply cropping and splicing the data, as Figure 4 shown.

[0102] S4. Establish a linear mapping relationship between the spherical screen UV coordinates and the display resolution (W×H), and achieve data accuracy matching through resampling.

[0103] Construct a linear mapping relationship between the LED spherical screen and the display resolution. The projection relationship formula is:

[0104]

[0105] where W×H is the physical display resolution.

[0106] Bilinear interpolation is used to compensate for discretization errors and achieve sub-pixel alignment:

[0107]

[0108] where ω m (Δu) = 1 - |Δu - m| is the linear weight function.

[0109] S5. Based on the pixel coordinates after rotation transformation, the void coverage area of the support structure is calculated in real time, and sub-pixel level data clipping operation is performed.

[0110] The 5th order spherical harmonic function is used for modeling to calculate the geometric shape of the mechanical structure of the spherical support:

[0111]

[0112] where a lm is the coefficient fitted according to the actual shape of the support structure, and l is the expansion order. For the rotated coordinate P', the original spherical coordinates are calculated:

[0113]

[0114] If θ' falls within the mechanical blind area, the pixel is clipped.

[0115] S6. The geographical data is rendered and output to the LED spherical screen in real time, and a double-buffer rendering mechanism is adopted to ensure rendering smoothness.

Claims

1. A dynamic adaptive display method for geographical data of an LED spherical display screen, characterized in that, Including the following steps: (1) Convert the longitude and latitude coordinates of the original geographic data into spherical parameter space Generate an effective display area Ω based on the physical parameters of the spherical screen; (2) According to the row pitch Δθ and column pitch of the spherical screen pixels Establish a discretized spherical grid model through a curvature compensation algorithm, and calculate the three-dimensional coordinates (x, y, z) of each pixel point; (3) Receive a three-dimensional rotation instruction (α, β, γ), generate a rotation matrix q(t) using a quaternion interpolation algorithm, and perform real-time coordinate transformation on the spherical screen pixel array; (4) Establish a linear mapping relationship between the spherical screen UV coordinates and the display resolution, and achieve data accuracy matching through resampling; (5) Based on the pixel coordinates after rotation transformation obtained in step (3), calculate the support structure void coverage area in real time, and perform sub-pixel level data clipping operations; (6) Render geographical data in real time to the LED spherical screen and adopt a double-buffer rendering mechanism.

2. The dynamic adaptive display method of geographic data for an LED spherical display screen according to claim 1, characterized in that In step (1), the longitude and latitude coordinates of the original geographic data are projected onto the sphere through spherical projection transformation, and the longitude and latitude geographic coordinates are mapped to the spherical surface using modified equidistant cylindrical projection to obtain the spherical parameter space θ = π(1 - v) where θ is the polar angle, is the azimuth angle, u is the normalized coordinate in the spherical longitude direction, v is the normalized coordinate in the spherical latitude direction, and u, v ∈ [0, 1].

3. The dynamic adaptive display method for geographic data for an LED spherical display screen according to claim 2, wherein According to the LED spherical screen diameter D and the set of support structure cavity parameters {d k}, the calculation of the polar angle θ constraint is as follows: where θ min is the minimum polar angle, and θ max is the maximum polar angle.

4. The dynamic adaptive display method for geographical data for an LED spherical display screen according to claim 3, characterized in that, The corrected polar angle θ is obtained by nonlinearly correcting the polar angle θ comp be θ comp = θ + k·sin(2θ) k∈[0.1,0.3]。 5. The method for dynamically and adaptively displaying geographic data for an LED spherical display screen according to claim 4, characterized in that Coordinate quantization, according to Δθ and discretize the continuous space into a grid 6. The dynamic adaptive display method for geographical data for an LED spherical display screen according to claim 5, characterized in that In step (2), the curvature compensation coefficient ξ is Non-uniform grid generation, number of pixels per layer is Calculate the three-dimensional coordinates of each discrete grid point :

7. The dynamic adaptive display method for geographic data for an LED spherical display screen according to claim 6, characterized in that Before calculating the three-dimensional coordinates, perform dynamic compensation to obtain Among them, is the equatorial reference interval; Adaptive division is performed according to the support structure occlusion range, and Δθ is dynamically adjusted as follows: Introduce a secondary curvature compensation term to correct the edge distortion of the spherical surface, eliminate the edge stretching caused by spherical mapping, make the shape of the edge regions such as Antarctica closer to the true projection, and the corrected polar angle θ 矫正 is θ 矫正 = θ + k·θ 2 k is the distortion coefficient obtained through actual measurement.

8. The method for dynamically and adaptively displaying geographic data for an LED spherical display screen according to claim 7, wherein Step (3) is specifically as follows: Calculate the unit quaternion q according to the three-dimensional rotation instruction (α, β, γ) as Adopt an interpolation algorithm, use a Squad curve to transition key frames to achieve smooth rotation, and obtain the rotation matrix q(t) as Perform per-pixel transformation to obtain the transformed coordinate P' as where P = [0, x, y, z] is the extended quaternion coordinate.

9. The method for dynamically and adaptively displaying geographical data for an LED spherical display screen according to claim 8, wherein The linear mapping matrix M between the spherical screen UV coordinates and the display resolution in step (4) proj is where W×H is the physical display resolution; Bilinear interpolation is used to compensate for the discretization error and align the sub-pixel I out (i, j): where Δu is the sub-pixel offset in the horizontal direction, Δv is the sub-pixel offset in the vertical direction, ω m (Δu) is the horizontal weight function (linear interpolation), ω n (Δv) is the vertical weight function (linear interpolation), and I in is the discrete pixel value of the input image.

10. The method for dynamically and adaptively displaying geographic data for an LED spherical display screen according to claim 9, wherein Calculating the void coverage area of the support structure in step (5) is where a lm is the coefficient fitted according to the shape of the support structure, Y l m is the orthonormal basis function in the spherical coordinate system, and l is the expansion order.

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