Member GDALIsLineOfSightVisible (const GDALRasterBandH, const int xA, const int yA, const double zA, const int xB, const int yB, const double zB, int *pnxTerrainIntersection, int *pnyTerrainIntersection, CSLConstList papszOptions): In order to reduce CPU cost and avoid a sqrt operation, consider the approach to just the ratio along x or y depending on whether the line is steep or shallow. See https://github.com/OSGeo/gdal/pull/9506#discussion_r1532459689.