Function GetVRT

alg/zonal.cpp:972–1037

  private:
    static std::unique_ptr<GDALDataset>
    GetVRT(GDALDataset &src, const GDALDataset &dst, bool &resampled)
    {
        resampled = false;

        GDALGeoTransform srcGT, dstGT;
        if (src.GetGeoTransform(srcGT) != CE_None)
        {
            return nullptr;
        }
        if (dst.GetGeoTransform(dstGT) != CE_None)
        {
            return nullptr;
        }

        CPLStringList aosOptions;
        aosOptions.AddString("-of");
        aosOptions.AddString("VRT");

        aosOptions.AddString("-ot");
        aosOptions.AddString("Float64");

        // Prevent warning message about Computed -srcwin outside source raster extent.
        // We've already tested for this an issued a more understandable message.
        aosOptions.AddString("--no-warn-about-outside-window");

        if (srcGT != dstGT || src.GetRasterXSize() != dst.GetRasterXSize() ||
            src.GetRasterYSize() != dst.GetRasterYSize())
        {
            const double dfColOffset =
                std::fmod(std::abs(srcGT.xorig - dstGT.xorig), dstGT.xscale);
            const double dfRowOffset =
                std::fmod(std::abs(srcGT.yorig - dstGT.yorig), dstGT.yscale);

            OGREnvelope oDstEnv;
            dst.GetExtent(&oDstEnv);

            aosOptions.AddString("-projwin");
            aosOptions.AddString(CPLSPrintf("%.17g", oDstEnv.MinX));
            aosOptions.AddString(CPLSPrintf("%.17g", oDstEnv.MaxY));
            aosOptions.AddString(CPLSPrintf("%.17g", oDstEnv.MaxX));
            aosOptions.AddString(CPLSPrintf("%.17g", oDstEnv.MinY));

            if (srcGT.xscale != dstGT.xscale || srcGT.yscale != dstGT.yscale ||
                std::abs(dfColOffset) > 1e-4 || std::abs(dfRowOffset) > 1e-4)
            {
                resampled = true;
                aosOptions.AddString("-r");
                aosOptions.AddString("average");
            }

            aosOptions.AddString("-tr");
            aosOptions.AddString(CPLSPrintf("%.17g", dstGT.xscale));
            aosOptions.AddString(CPLSPrintf("%.17g", std::abs(dstGT.yscale)));
        }

        std::unique_ptr<GDALDataset> ret;