GDAL RPC Transformer Error when use dem

[liminlu0314]

When correcting images with RPC, if the specified DEM interpolation algorithm is ‘near’, the transformed result will be wrong. The reason is that when interpolates DEM with ‘near’, the storage type of elevation values that RasterIO function read is inconsistent with specified type, the former is a double while the latter a GDT_Int32, thus leads to this error. The patch is to change the GDT_Int32 to GDT_Float64, which can modify this bug. in line 778 and 913 of file gdal_rpc.cpp.

old code

                else
                {
                    if (!(dX >= 0 && dY >= 0 && dX <= nRasterXSize && dY <= nRasterYSize))
                    {
                        panSuccess[i] = FALSE;
                        continue;
                    }
                    CPLErr eErr = psTransform->poDS->RasterIO(GF_Read, dX, dY, 1, 1,
                                                              &dfDEMH, 1, 1,
                                                              GDT_Int32, 1, bands, 0, 0, 0);
                    if(eErr != CE_None)
                    {
                        panSuccess[i] = FALSE;
                        continue;
                    }              
                }                

new code

                else
                {
                    if (!(dX >= 0 && dY >= 0 && dX <= nRasterXSize && dY <= nRasterYSize))
                    {
                        panSuccess[i] = FALSE;
                        continue;
                    }
                    CPLErr eErr = psTransform->poDS->RasterIO(GF_Read, dX, dY, 1, 1,
                                                              &dfDEMH, 1, 1,
                                                              GDT_Float64, 1, bands, 0, 0, 0);
                    if(eErr != CE_None)
                    {
                        panSuccess[i] = FALSE;
                        continue;
                    }              
                }                

[Even Rouault]

Thanks a lot !

trunk r27485, branches/1.11 r27486 "RPC transformer with DEM: fix near interpolation (patch by liminlu0314, #5553)"