RASTER_getPixelValueResample()

Datum RASTER_getPixelValueResample

(

PG_FUNCTION_ARGS

)

Definition at line 165 of file rtpg_pixel.c.

{
        rt_raster raster = NULL;
        rt_band band = NULL;
        rt_pgraster *pgraster = (rt_pgraster *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
        int32_t bandnum = PG_GETARG_INT32(1);
        GSERIALIZED *gser;
        LWPOINT *lwpoint;
        LWGEOM *lwgeom;
        bool exclude_nodata_value = PG_GETARG_BOOL(3);
        rt_resample_type resample_type = RT_NEAREST;
        double x, y, xr, yr;
        double pixvalue = 0.0;
        int isnodata = 0;
        rt_errorstate err;
 
        /* Index is 1-based */
        if (bandnum < 1) {
                elog(NOTICE, "Invalid band index (must use 1-based). Returning NULL");
                PG_RETURN_NULL();
        }
 
        gser = (GSERIALIZED*)PG_DETOAST_DATUM(PG_GETARG_DATUM(2));
        if (gserialized_get_type(gser) != POINTTYPE || gserialized_is_empty(gser)) {
                elog(ERROR, "Attempting to get the value of a pixel with a non-point geometry");
                PG_RETURN_NULL();
        }
 
        raster = rt_raster_deserialize(pgraster, FALSE);
        if (!raster) {
                elog(ERROR, "RASTER_getPixelValue: Could not deserialize raster");
                PG_RETURN_NULL();
        }
 
        if (gserialized_get_srid(gser) != rt_raster_get_srid(raster)) {
                elog(ERROR, "Raster and geometry do not have the same SRID");
                PG_RETURN_NULL();
        }
 
        if (PG_NARGS() > 4) {
                text *resample_text = PG_GETARG_TEXT_P(4);
                resample_type = resample_text_to_type(resample_text);
        }
 
        /* Fetch Nth band using 0-based internal index */
        band = rt_raster_get_band(raster, bandnum - 1);
        if (!band) {
                elog(NOTICE, "Could not find raster band of index %d when getting pixel "
                                        "value. Returning NULL", bandnum);
                PG_RETURN_NULL();
        }
 
        /* Get the X/Y coordinates */
        lwgeom = lwgeom_from_gserialized(gser);
        lwpoint = lwgeom_as_lwpoint(lwgeom);
        x = lwpoint_get_x(lwpoint);
        y = lwpoint_get_y(lwpoint);
 
        /* Convert X/Y world coordinates into raster coordinates */
        err = rt_raster_geopoint_to_rasterpoint(raster, x, y, &xr, &yr, NULL);
        if (err != ES_NONE) {
                elog(ERROR, "Could not convert world coordinate to raster coordinate");
                PG_RETURN_NULL();
        }
 
        /* Use appropriate resample algorithm */
        err = rt_band_get_pixel_resample(
                band,
                xr, yr,
                resample_type,
                &pixvalue, &isnodata
                );
 
        /* If the result is -1 or the value is nodata and we take nodata into account
         * then return nodata = NULL */
        rt_raster_destroy(raster);
        lwgeom_free(lwgeom);
        if (err != ES_NONE || (exclude_nodata_value && isnodata)) {
                PG_RETURN_NULL();
        }
        PG_RETURN_FLOAT8(pixvalue);
}

References ES_NONE, FALSE, gserialized_get_srid(), gserialized_get_type(), gserialized_is_empty(), lwgeom_as_lwpoint(), lwgeom_free(), lwgeom_from_gserialized(), lwpoint_get_x(), lwpoint_get_y(), POINTTYPE, resample_text_to_type(), rt_band_get_pixel_resample(), RT_NEAREST, rt_raster_deserialize(), rt_raster_destroy(), rt_raster_geopoint_to_rasterpoint(), rt_raster_get_band(), and rt_raster_get_srid().

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