It is possible to apply an arbitrary warping mesh to distort the final image using a PFM (portable float map) file.
The file format is rather simple, and is described here. The file contains an array of NxM 3-component pixels in RGB (grayscale not supported). Each position contains the mapped resulting location in UV, in the R and G components respectively, in . The geometry warp format is the same as in the MPCDI v2.0 specification, section 3.6.2 (see here).
This file is read and converted into a mesh by Gaia Sky. The mesh is used to distort the final image at the end of the rendering pipeline.
In order to specify a PFM warping mesh file, you need to edit the configuration file of Gaia Sky and add a few lines in the
postprocess: [...] warpingMesh: pfmFile: /path/to/your/warping-mesh.pfm
A few warping mesh examples (big endian) are provided below:
warp-identity.pfm– identity function, .
Flip X –
warp-invert-x.pfm– flips the X coordinate, .
Flip Y –
warp-invert-y.pfm– flips the Y coordinate, .
Flip XY –
warp-invert-xy.pfm– flips the X and Y coordinates, .
warp-x2.pfm– applies a square function to X, .
X^2, Y^2 –
warp-x2y2.pfm– applies a square function to X and Y, .