How to manipulate the grid points for some warping application about camera_calibration HOT 1 OPEN

1. The grid points are used with B-Spline interpolation to look up the viewing direction corresponding to a given image pixel (see our paper for an illustration). In order to manually set up the generic camera model to represent some other ideal camera model, there are two options:
   • If the B-Spline interpolation result can represent your ideal camera perfectly, then it should be sufficient to set each grid point to the corresponding viewing direction at the grid point's pixel, as computed from the ideal model.
   • If the ideal camera model cannot be represented perfectly, the procedure above can still be used, but it will only initialize the model approximately. As a refinement step, one can then optimize the grid point values to match the ideal model as closely as possible.
   • These two steps are implemented in: CentralGenericModel::FitToDenseModel(const Image<Vec3d>& dense_model, int subsample_step, int max_iteration_count)
2. Yes, these parameters simply represent a bounding box for the calibrated image area in pixel coordinates. The calibration is only valid for pixels within this bounding box.

from camera_calibration.