RASTER_getPixelValue()

Datum RASTER_getPixelValue

(

PG_FUNCTION_ARGS

)

Definition at line 73 of file rtpg_pixel.c.

{
    rt_pgraster *pgraster = NULL;
    rt_raster raster = NULL;
    rt_band band = NULL;
    double pixvalue = 0;
    int32_t bandindex = 0;
    int32_t x = 0;
    int32_t y = 0;
    int result = 0;
    bool exclude_nodata_value = TRUE;
                int isnodata = 0;
 
    /* Index is 1-based */
    bandindex = PG_GETARG_INT32(1);
    if ( bandindex < 1 ) {
        elog(NOTICE, "Invalid band index (must use 1-based). Returning NULL");
        PG_RETURN_NULL();
    }
 
    x = PG_GETARG_INT32(2);
 
    y = PG_GETARG_INT32(3);
 
    exclude_nodata_value = PG_GETARG_BOOL(4);
 
    POSTGIS_RT_DEBUGF(3, "Pixel coordinates (%d, %d)", x, y);
 
    /* Deserialize raster */
    if (PG_ARGISNULL(0)) PG_RETURN_NULL();
    pgraster = (rt_pgraster *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
 
    raster = rt_raster_deserialize(pgraster, FALSE);
    if (!raster) {
        PG_FREE_IF_COPY(pgraster, 0);
        elog(ERROR, "RASTER_getPixelValue: Could not deserialize raster");
        PG_RETURN_NULL();
    }
 
    /* Fetch Nth band using 0-based internal index */
    band = rt_raster_get_band(raster, bandindex - 1);
    if (! band) {
        elog(NOTICE, "Could not find raster band of index %d when getting pixel "
                "value. Returning NULL", bandindex);
        rt_raster_destroy(raster);
        PG_FREE_IF_COPY(pgraster, 0);
        PG_RETURN_NULL();
    }
    /* Fetch pixel using 0-based coordinates */
    result = rt_band_get_pixel(band, x - 1, y - 1, &pixvalue, &isnodata);
 
    /* If the result is -1 or the value is nodata and we take nodata into account
     * then return nodata = NULL */
    if (result != ES_NONE || (exclude_nodata_value && isnodata)) {
        rt_raster_destroy(raster);
        PG_FREE_IF_COPY(pgraster, 0);
        PG_RETURN_NULL();
    }
 
    rt_raster_destroy(raster);
    PG_FREE_IF_COPY(pgraster, 0);
 
    PG_RETURN_FLOAT8(pixvalue);
}

References ovdump::band, ES_NONE, FALSE, POSTGIS_RT_DEBUGF, rtrowdump::raster, rt_band_get_pixel(), rt_raster_deserialize(), rt_raster_destroy(), rt_raster_get_band(), TRUE, pixval::x, and pixval::y.

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