Use ST_RPCRectify to rectify raster data - PolarDB

Rectifies a raster object based on rational polynomial coefficients (RPC) parameters and returns the rectified raster.

Syntax

raster ST_RPCRectify(raster rast,
                    raster dem DEFAULT NULL,
                    cstring rectifyOption DEFAULT '{}',
                    cstring storageOption DEFAULT '{}',
                    cstring parallelOption DEFAULT '{}')

Prerequisites

The raster object must contain RPC information.

Parameters

Parameter	Type	Default	Description
`rast`	raster	—	The raster object to rectify.
`dem`	raster	NULL	A digital elevation model (DEM) referenced during rectification. Default value: NULL.
`rectifyOption`	cstring	`'{}'`	Rectification options as a JSON string.
`storageOption`	cstring	`'{}'`	Output storage options as a JSON string.
`parallelOption`	cstring	`'{}'`	Parallel processing options as a JSON string.

rectifyOption parameters

Parameter	Type	Default	Notes
`resample`	string	`'Near'`	Resampling method. Valid values: `Near`, `Average`, `Cubic`, `Bilinear`.
`outSrid`	integer	Same as source	Spatial reference identifier (SRID) for the output raster.
`nodataValue`	float8 or float8[]	NULL	Nodata value for the output raster bands. Specify a single value to apply it to all bands, or an array (e.g., `[0, 0, 0]`) with one element per band. If omitted, the value is inherited from the source raster; if the source has no nodata value, defaults to `0`.
`RPC_DEM_MISSING_VALUE`	float8	0	Height value used when the DEM has a nodata value at the sample point, or when the sample coordinate falls outside the DEM extent.

storageOption parameters

Parameter	Type	Default	Notes
`chunking`	boolean	Same as source	Whether to store the output as chunks.
`chunkdim`	string	Same as source	Chunk dimensions. Takes effect only when `chunking` is `true`.
`chunktable`	string	`''`	Name of the chunk table. If set to `''`, a temporary chunk table with a random name is created for the current session and deleted when the session ends. To persist the output raster, specify a table name. If the parallel method does not support chunk tables created by anonymous users, create the chunk table before calling the function.
`compression`	string	Same as source	Compression format. Valid values: `NONE`, `JPEG`, `ZLIB`, `PNG`, `LZO`, `LZ4`, `JP2K`.
`quality`	integer	Same as source	Compression quality. Takes effect only with `JPEG` compression.
`interleaving`	string	Same as source	Band interleaving format. Valid values: `bip` (band interleaved by pixel), `bil` (band interleaved by line), `bsq` (band sequential).
`endian`	string	Same as source	Byte order of the output raster. Valid values: `NDR` (little endian), `XDR` (big endian).

Examples

The following examples use a table that stores both the source RPC raster and the DEM. Set up the tables first:

CREATE TABLE IF NOT EXISTS raster_table (id integer, rast raster);
CREATE TABLE raster_result (id integer, rast raster);

-- Load the RPC raster data
INSERT INTO raster_table VALUES (1, ST_ImportFrom('t_chunk', '<RAST_DATA_DIR>/rpc.tif', '{}'));

-- Load the DEM data
INSERT INTO raster_table VALUES (2, ST_ImportFrom('t_chunk', '<RAST_DATA_DIR>/rpc_dem.tif', '{}'));

Replace <RAST_DATA_DIR> with the directory path containing your raster files.

Rectify without a DEM

Use nearest neighbor resampling (NNS method) without specifying a DEM:

INSERT INTO raster_result (id, rast)
SELECT 10, ST_RPCRectify(
    rast,
    NULL,
    '{"resample": "Near"}',
    '{"chunking": true, "chunkdim": "(256,256,1)", "interleaving": "bsq", "chunktable": "t_chunk"}'
)
FROM raster_table
WHERE id = 1;

Rectify with a DEM and parallel processing

Use nearest neighbor resampling (NNS method) with a DEM and parallel processing:

INSERT INTO raster_result (id, rast)
SELECT 11, ST_RPCRectify(
    rast,
    (SELECT rast FROM raster_table WHERE id = 2),
    '{"resample": "Near", "outSrid": 32635}',
    '{"chunking": true, "chunkdim": "(256,256,1)", "interleaving": "bsq", "chunktable": "t_chunk"}',
    '{"parallel": 8}'
)
FROM raster_table
WHERE id = 1;