WarpGrid

Data Structures
struct	VPIWarpGrid
	Holds VPI's warp grid definition. More...

Macros
#define	VPI_WARPGRID_MAX_HORIZ_REGIONS_COUNT   4
	Maximum number of regions horizontally in a warp grid.
#define	VPI_WARPGRID_MAX_VERT_REGIONS_COUNT   4
	Maximum number of regions vertically in a warp grid.
#define	VPI_WARPGRID_MIN_REGION_WIDTH   64
	Minimum warp grid region width.
#define	VPI_WARPGRID_MIN_REGION_HEIGHT   16
	Minimum warp grid region height.

Detailed Description

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Data Structure Documentation

VPIWarpGrid

struct VPIWarpGrid

Holds VPI's warp grid definition.

This structure defines the layout of the control points in the destination image of a image remap operation.

The control points are used as the basis for geometric transformation from source image to destination image. The remaining points are transformed based on the interpolation. Thus the density of the control points controls the quality of the geometric transformation.

This is an example of defining regions in the image:

           warp grid width
     /                         \
    /                           \
   /                             \
 
regionWidth[0]    regionWidth[numHorizRegions-1]
   /    \                  /    \
  |------|                |------|
  --------------------------------                                 \
  |******* *******        *******|--                                \
  |* . . * *     *        *     *|  \                                \
  |* . . * *     *  ...   *     *|   regionHeight[0]                  \
  |* . . * *     *        *     *|  /                                  \
  |******* *******        *******|--                                    \
  |                              |                                       \
  |   .       .              .   |                                  
  |   .       .              .   |                                         warp grid height
  |   .       .              .   |
  |                              |                                       /
  |******* *******        *******|--                                    /
  |*     * *     *        *     *|  \                                  /
  |*     * *     *  ...   *     *|   regionHeight[numVertRegions-1]   /
  |*     * *     *        *     *|  /                                /
  |******* *******        *******|--                                /  
  --------------------------------                                 /

This is an example of defining control points in one region:

 *********
 *  +  + *-- \
 *       *    vertInterval
 *  +  + *-- /
 *       *
 *********
    |--|
horizInterval

Here's an example of a WxH dense grid definition:

VPIWarpGrid grid;
grid.numHorizRegions  = 1;
grid.numVertRegions   = 1;
grid.horizInterval[0] = 1;
grid.vertInterval[0]  = 1;
grid.regionWidth[0]   = W;
grid.regionHeight[0]  = H;

Restrictions

• numHorizRegions cannot exceed VPI_WARPGRID_MAX_HORIZ_REGIONS_COUNT.
• numVertRegions cannot exceed VPI_WARPGRID_MAX_VERT_REGIONS_COUNT.
• Intervals must be power-of-two.
• Alignment restrictions:
  • regionWidth[0] to regionWidth[numHorizRegions-2] must be aligned to VPI_WARPGRID_MIN_REGION_WIDTH and at least VPI_WARPGRID_MIN_REGION_WIDTH.
  • regionWidth[numHorizRegions-1] must be at least VPI_WARPGRID_MIN_REGION_WIDTH.
  • regionHeight[0] to regionHeight[numVertRegions-2] must be aligned to VPI_WARPGRID_MIN_REGION_HEIGHT and at least VPI_WARPGRID_MIN_REGION_HEIGHT.
  • regionHeight[numVertRegions-1] must be at least VPI_WARPGRID_MIN_REGION_HEIGHT.

Definition at line 155 of file WarpGrid.h.

Collaboration diagram for VPIWarpGrid:

Data Fields
uint16_t	horizInterval[VPI_WARPGRID_MAX_HORIZ_REGIONS_COUNT]	Horizontal spacing between control points within a given region. Must be power-of-two.
uint8_t	numHorizRegions	Number of regions horizontally.
uint8_t	numVertRegions	Number of regions vertically.
uint16_t	regionHeight[VPI_WARPGRID_MAX_VERT_REGIONS_COUNT]	Height of each region.
uint16_t	regionWidth[VPI_WARPGRID_MAX_HORIZ_REGIONS_COUNT]	Width of each region.
uint16_t	vertInterval[VPI_WARPGRID_MAX_VERT_REGIONS_COUNT]	Vertical spacing between control points within a given region. Must be power-of-two.