GPKG -- GeoPackage raster

Driver short name

GPKG

Build dependencies

libsqlite3 (and any or all of PNG, JPEG, WEBP drivers)

This driver implements full read/creation/update of tables containing raster tiles in the OGC GeoPackage format standard. The GeoPackage standard uses a SQLite database file as a generic container, and the standard defines:

Expected metadata tables (gpkg_contents, gpkg_spatial_ref_sys, gpkg_tile_matrix, gpkg_tile_matrix_set, ...)
Tile format encoding (PNG and JPEG for base specification, WebP as extension) and tiling conventions
Naming and conventions for extensions

This driver reads and writes SQLite files from the file system, so it must be run by a user with read/write access to the files it is working with.

The driver can also handle GeoPackage vectors. See GeoPackage vector documentation page

Various kind of input datasets can be converted to GeoPackage raster :

Single band grey level
Single band with R,G,B or R,G,B,A color table
Two bands: first band with grey level, second band with alpha channel
Three bands: Red, Green, Blue
Four band: Red, Green, Blue, Alpha

GeoPackage rasters only support Byte data type.

All raster extensions standardized by the GeoPackage specification are supported in read and creation :

gpkg_webp: when storing WebP tiles, provided that GDAL is compiled against libwebp.
gpkg_zoom_other: when resolution of consecutive zoom levels does not vary with a factor of 2.

Driver capabilities

Supports CreateCopy()

This driver supports the GDALDriver::CreateCopy() operation

Supports Create()

This driver supports the GDALDriver::Create() operation

Supports Georeferencing

This driver supports georeferencing

Supports VirtualIO

This driver supports virtual I/O operations (/vsimem/, etc.)

Opening options

By default, the driver will expose a GeoPackage dataset as a four band (Red,Green, Blue,Alpha) dataset, which gives the maximum compatibility with the various encodings of tiles that can be stored. It is possible to specify an explicit number of bands with the BAND_COUNT opening option. Starting with GDAL 3.6, a special metadata item is written when creating a GeoPackage raster with GDAL (when using the default CUSTOM tiling scheme), and it is used on reading as the default number of bands.

The driver will use the geographic/projected extent indicated in the gpkg_contents table, and do necessary clipping, if needed, to respect that extent. However that information being optional, if omitted, the driver will use the extent provided by the gpkg_tile_matrix_set, which covers the extent at all zoom levels. The user can also specify the USE_TILE_EXTENT=YES open option to use the actual extent of tiles at the maximum zoom level. Or it can specify any of MINX/MINY/MAXX/MAXY to have a custom extent.

Open options can be specified in command-line tools using the syntax -oo <NAME>=<VALUE> or by providing the appropriate arguments to GDALOpenEx() (C) or gdal.OpenEx (Python). The following open options are available:

TABLE=<table_name>: Name of the table containing the tiles (called "Tile Pyramid User Data Table" in the GeoPackage specification language). If the GeoPackage dataset only contains one table, this option is not necessary. Otherwise, it is required.
ZOOM_LEVEL=value: Integer value between 0 and the maximum filled in the gpkg_tile_matrix table. By default, the driver will select the maximum zoom level, such as at least one tile at that zoom level is found in the raster table.
BAND_COUNT=[AUTO/1/2/3/4]: Number of bands of the dataset exposed after opening. Only used for Byte data type. Some conversions will be done when possible and implemented, but this might fail in some cases, depending on the BAND_COUNT value and the number of bands of the tile. Before GDAL 3.6, the default value is 4 (which is the always safe value). Starting with GDAL 3.6, when the metadata of the file contains an hint of the number of bands, this one is used in AUTO mode (default value), or fallback to 4 when it is not present.
MINX=value: Minimum longitude/easting of the area of interest.
MINY=value: Minimum latitude/northing of the area of interest.
MAXX=value: Maximum longitude/easting of the area of interest.
MAXY=value: Maximum latitude/northing of the area of interest.
USE_TILE_EXTENT=[YES/NO]: Defaults to NO. Whether to use the extent of actual existing tiles at the zoom level of the full resolution dataset.
TILE_FORMAT=[PNG_JPEG/PNG/PNG8/JPEG/WEBP]: Format used to store tiles. See Tile formats. Only used in update mode and for Byte data type. Defaults to PNG_JPEG, unless, starting with GDAL 3.6, if the raster has one band, in which case PNG is used.
QUALITY=1-100: Defaults to 75. Quality setting for JPEG and WEBP compression. Only used in update mode.
ZLEVEL=1-9: Defaults to 6. DEFLATE compression level for PNG tiles. Only used in update mode.
DITHER=[YES/NO]: Defaults to NO. Whether to use Floyd-Steinberg dithering (for TILE_FORMAT=PNG8). Only used in update mode.

Note: open options are typically specified with "-oo name=value" syntax in most GDAL utilities, or with the GDALOpenEx() API call.

Creation issues

Depending of the number of bands of the input dataset and the tile format selected, the driver will do the necessary conversions to be compatible with the tile format.

To add several tile tables to a GeoPackage dataset (seen as GDAL subdatasets), or to add a tile table to an existing vector-only GeoPackage, the generic APPEND_SUBDATASET=YES creation option must be provided.

Fully transparent tiles will not be written to the database, as allowed by the format.

The driver implements the Create() and IWriteBlock() methods, so that arbitrary writing of raster blocks is possible, enabling the direct use of GeoPackage as the output dataset of utilities such as gdalwarp.

On creation, raster blocks can be written only if the geotransformation matrix has been set with SetGeoTransform() This is effectively needed to determine the zoom level of the full resolution dataset based on the pixel resolution, dataset and tile dimensions.

Technical/implementation note: when a dataset is opened with a non-default area of interest (i.e. use of MINX,MINY,MAXX,MAXY or USE_TILE_EXTENT open option), or when creating/ opening a dataset with a non-custom tiling scheme, it is possible that GDAL blocks do not exactly match a single GeoPackage tile. In which case, each GDAL block will overlap four GeoPackage tiles. This is easily handled on the read side, but on creation/update side, such configuration could cause numerous decompression/ recompression of tiles to be done, which might cause unnecessary quality loss when using lossy compression (JPEG, WebP). To avoid that, the driver will create a temporary database next to the main GeoPackage file to store partial GeoPackage tiles in a lossless (and uncompressed) way. Once a tile has received data for its four quadrants and for all the bands (or the dataset is closed or explicitly flushed with FlushCache()), those uncompressed tiles are definitely transferred to the GeoPackage file with the appropriate compression. All of this is transparent to the user of GDAL API/utilities

The driver updates the GeoPackage last_change timestamp when the file is created or modified. If consistent binary output is required for reproducibility, the timestamp can be forced to a specific value by setting the OGR_CURRENT_DATE global configuration option. When setting the option, take care to meet the specific time format requirement of the GeoPackage standard, e.g. for version 1.2.

Tile formats

Tiled rasters

This section only applies for raster of Byte data type.

GeoPackage can store tiles in different formats, PNG and/or JPEG for the baseline specification, and WebP for extended GeoPackage. Support for those tile formats depend if the underlying drivers are available in GDAL, which is generally the case for PNG and JPEG, but not necessarily for WebP since it requires GDAL to be compiled against the optional libwebp.

By default, GDAL will use a mix of PNG and JPEG tiles (PNG_JPEG tile format, or AUTO). PNG tiles will be used to store tiles that are not completely opaque, either because input dataset has an alpha channel with non fully opaque content, or because tiles are partial due to clipping at the right or bottom edges of the raster, or when a dataset is opened with a non-default area of interest, or with a non-custom tiling scheme. On the contrary, for fully opaque tiles, JPEG format will be used. Starting with GDAL 3.6, if the raster has only one band, the default is PNG.

It is possible to select one unique tile format by setting the creation/open option TILE_FORMAT to one of PNG, JPEG or WEBP. When using JPEG, the alpha channel will not be stored. When using WebP, the gpkg_webp extension will be registered. The lossy compression of WebP is used. Note that a recent enough libwebp (>=0.1.4) must be used to support alpha channel in WebP tiles.

PNG8 can be selected to use 8-bit PNG with a color table up to 256 colors. On creation, an optimized color table is computed for each tile. The DITHER option can be set to YES to use Floyd/Steinberg dithering algorithm, which spreads the quantization error on neighbouring pixels for better rendering (note however than when zooming in, this can cause non desirable visual artifacts). Setting it to YES will generally cause less effective compression. Note that at that time, such an 8-bit PNG formulation is only used for fully opaque tiles, as the median-cut algorithm currently implemented to compute the optimal color table does not support alpha channel (even if PNG8 format would potentially allow color table with transparency). So when selecting PNG8, non fully opaque tiles will be stored as 32-bit PNG.

Tiled gridded coverage data

Since GDAL 2.3, tiled gridded coverage data can be stored using PNG unsigned 16bit tiles (with potential offset and scaling so as to be able to represent floating point data) or TIFF 32-bit floating-point LZW compressed tiles.

When converting a GDAL Int16 or UInt16 dataset, PNG tiles will be used. When converting a GDAL Float32 dataset, TIFF tiles will be used by default, unless PNG is explicitly selected, in which case scaling and offsetting will be automatically computed for each tile.

警告

The tiled gridded extension initially implemented in GDAL 2.2 was not officially adopted and had been later reworked by OGC. The adopted tiled gridded coverage data has a few differences that will make GDAL 2.2 datasets not be compliant with the final extension. GDAL 2.3 can open those GDAL 2.2-generated files.

Tiling schemes

By default, conversion to GeoPackage will create a custom tiling scheme, such that the input dataset can be losslessly converted, both at the pixel and georeferencing level (if using a lossless tile format such as PNG). That tiling scheme is such that its origin (min_x, max_y) in the gpkg_tile_matrix_set table perfectly matches the top left corner of the dataset, and the selected resolution (pixel_x_size, pixel_y_size) at the computed maximum zoom_level of the gpkg_tile_matrix table will match the pixel width and height of the raster.

However to ease interoperability with other implementations, and enable use of GeoPackage with tile servicing software, it is possible to select a predefined tiling scheme that has world coverage. The available tiling schemes are :

GoogleMapsCompatible, as described in WMTS 1.0 specification, Annex E.4. That tiling schemes consists of a single 256x256 tile at its zoom level 0, in EPSG:3857 CRS, with extent in easting and northing in the range [-20037508.34,20037508.34].
InspireCRS84Quad, as described in Inspire View Services. That tiling schemes consists of two 256x256 tiles at its zoom level 0, in EPSG:4326 CRS, with extent in longitude in the range [-180,180] and in latitude in the range [-90,90].
PseudoTMS_GlobalGeodetic, based on the global-geodetic profile of OSGeo TMS (Tile Map Service) specification. This has exactly the same definition as InspireCRS84Quad tiling scheme. Note however that full interoperability with TMS is not possible due to the origin of numbering of tiles being the top left corner in GeoPackage (consistently with WMTS convention), whereas TMS uses the bottom left corner as origin.
PseudoTMS_GlobalMercator, based on the global-mercator profile of OSGeo TMS (Tile Map Service) specification. That tiling schemes consists of four 256x256 tiles at its zoom level 0, in EPSG:3857 CRS, with extent extent in easting and northing in the range [-20037508.34,20037508.34]. The same remark as with PseudoTMS_GlobalGeodetic applies regarding interoperability with TMS.
GoogleCRS84Quad, as described in OGC 07-057r7 WMTS 1.0 specification, Annex E.3. That tiling schemes consists of a single 256x256 tile at its zoom level 0, in EPSG:4326 CRS, with extent in longitude and latitude in the range [-180,180]. Consequently, at zoom level 0, 64 lines are unused at the top and bottom of that tile. This may cause issues with some implementations of the specification, and there are some ambiguities about the exact definition of this tiling scheme. Using InspireCRS84Quad/PseudoTMS_GlobalGeodetic instead is therefore recommended. NOTE: OGC WMTS Simple Profile 13-082r2 changed the definition of GoogleCRS84Quad (so not implemented by the driver). The new definition includes a -1 level (that cannot be modeled in GeoPackage given constraints on zoom_level being positive or 0), with a single tile at origin -180,90 and whose bottom 128 lines are empty. Levels 0 or greater are identical to the InspireCRS84Quad tiling scheme. So for practical purposes, InspireCRS84Quad in GeoPackage is conformant to the new GoogleCRS84Quad definition.

In all the above tiling schemes, consecutive zoom levels defer by a resolution of a factor of two.

Starting with GDAL 3.2, it is also possible to use a Tile Matrix Set definition, encoded as a JSON file, according to the OGC Two Dimensional Tile Matrix Set standard Examples of such files can be found at http://schemas.opengis.net/tms/1.0/json/examples/ The GDAL data directory also contains files prefixed with tms_ and with a .json extension. If there is a tms_FOO.json file, then FOO can be used as the value of the TILING_SCHEME creation option. There are restrictions on the types of tile matrix set supported:

all zoom levels must have the same origin
consecutive zoom levels defer by a resolution of a factor of two.
all zoom levels must have the same tile dimension
variable matrix width tile set are not supported.

Nodata value

The concept of the nodata value is only supported for tiled gridded elevation datasets. For regular tiled rasters, the alpha band must rather be used.

For Float32 datasets with TIFF tiles, the concepts of nodata in GDAL and null_value in the GeoPackage internals perfectly match.

For Int16, UInt16 or Float32 with PNG tiles, GDAL will generally remap the input nodata value to another value.

On writing, for PNG tiles, the behavior is the following one:

GDAL data type	Input GDAL nodata value	null_value in GPKG gpkg_2d_gridded_coverage_ancillary
Int16	Any	65535
UInt16	X (if coverage offset == 0 and coverage scale == 1)	X
Float32	Any	65535

On reading, for PNG tiles, the behavior is the following one:

GDAL data type	null_value in GPKG gpkg_2d_gridded_coverage_ancillary	Exposed GDAL nodata value
Int16	>= 32768	-32768
Int16	X <= 32767	X
UInt16	X	X
Float32	X	X

Thus, perfect roundtripping is achieved in the following cases:

GDAL data type	GDAL nodata value	null_value in GPKG gpkg_2d_gridded_coverage_ancillary
Int16	-32768	65535
UInt16	X (if coverage offset == 0 and coverage scale == 1)	X
Float32	65535	65535

Creation options

Creation options can be specified in command-line tools using the syntax -co <NAME>=<VALUE> or by providing the appropriate arguments to GDALCreate() (C) or Driver.Create (Python). The following creation options are available:

RASTER_TABLE=value: Name of tile user table. By default, based on the filename (i.e. if filename is foo.gpkg, the table will be called "foo").
APPEND_SUBDATASET=[YES/NO]: Defaults to NO. If set to YES, an existing GeoPackage will not be priorly destroyed, such as to be able to add new content to it.
RASTER_IDENTIFIER=value: Human-readable identifier (e.g. short name), put in the identifier column of the gpkg_contents table.
RASTER_DESCRIPTION=value: Human-readable description, put in the description column of the gpkg_contents table.
BLOCKSIZE=<integer>: Defaults to 256. Block size in width and height in pixels. Maximum supported is 4096. Should not be set when using a non-custom TILING_SCHEME.
BLOCKXSIZE=<integer>: Defaults to 256. Block width in pixels. Maximum supported is 4096.
BLOCKYSIZE=<integer>: Defaults to 256. Block height in pixels. Maximum supported is 4096.
TILE_FORMAT=[PNG_JPEG/PNG/PNG8/JPEG/WEBP/TIFF/AUTO]: Defaults to AUTO. Format used to store tiles. See Tile formats.
QUALITY=1-100: Defaults to 75. Quality setting for JPEG and WEBP compression.
ZLEVEL=1-9: Defaults to 6. DEFLATE compression level for PNG tiles.
DITHER=[YES/NO]: Defaults to NO. Whether to use Floyd-Steinberg dithering (for TILE_FORMAT=PNG8).
TILING_SCHEME=[CUSTOM/GoogleCRS84Quad/GoogleMapsCompatible/InspireCRS84Quad/PseudoTMS_GlobalGeodetic/PseudoTMS_GlobalMercator/other]: Defaults to CUSTOM. See Tiling schemes.
Starting with GDAL 3.2, the value of TILING_SCHEME can also be the filename of a JSON file according to the OGC Two Dimensional Tile Matrix Set standard, a URL to such file, the radical of a definition file in the GDAL data directory (e.g. FOO for a file named tms_FOO.json) or the inline JSON definition. Note: the TILING_SCHEME option with a non-CUSTOM value is best used with the gdal_translate utility / CreateCopy() API operation. If used with gdalwarp, it requires setting the -tr switch to the exact value expected by one zoom level of the tiling scheme.

In non-CUSTOM mode, the actual resolution can be controlled with the ZOOM_LEVEL or ZOOM_LEVEL_STRATEGY options.
ZOOM_LEVEL=<integer>: (GDAL >= 3.9) Zoom level number (starting at 0 for coarsest zoom level). Only used for TILING_SCHEME different from CUSTOM. If this option is specified, ZOOM_LEVEL_STRATEGY is ignored.
ZOOM_LEVEL_STRATEGY=[AUTO/LOWER/UPPER]: Defaults to AUTO. Strategy to determine zoom level. Only used by CreateCopy() for TILING_SCHEME different from CUSTOM. LOWER will select the zoom level immediately below the theoretical computed non-integral zoom level, leading to subsampling. On the contrary, UPPER will select the immediately above zoom level, leading to oversampling. Defaults to AUTO which selects the closest zoom level.
RESAMPLING=[NEAREST/BILINEAR/CUBIC/CUBICSPLINE/LANCZOS/MODE/AVERAGE]: Defaults to BILINEAR. Resampling algorithm. Only used by CreateCopy() for TILING_SCHEME different from CUSTOM. Defaults to BILINEAR.
PRECISION=<floating_point_value_in_vertical_units>: Defaults to 1.0. Smallest significant value. Only used for tile gridded coverage datasets.
UOM=value: Unit of Measurement. Only used for tiled gridded coverage datasets. Also set through SetUnitType()
FIELD_NAME=value: Defaults to Height. Field name. Only used for tiled gridded coverage datasets.
QUANTITY_DEFINITION=value: Defaults to Height. Description of the field. Only used for tiled gridded coverage datasets.
GRID_CELL_ENCODING=[grid-value-is-center/grid-value-is-area/grid-value-is-corner]: Grid cell encoding. Only used for tiled gridded coverage datasets. Defaults to grid-value-is-center, when AREA_OR_POINT metadata item is not set.
VERSION=[AUTO/1.0/1.1/1.2/1.3]: Set GeoPackage version (for application_id and user_version fields). In AUTO mode, this will be equivalent to 1.2 starting with GDAL 2.3. 1.3 is available starting with GDAL 3.3
ADD_GPKG_OGR_CONTENTS=[YES/NO]: Defaults to YES. Defines whether to add a gpkg_ogr_contents table to keep feature count for vector layers, and associated triggers.
CRS_WKT_EXTENSION=[YES/NO]: (GDAL >= 3.8) Defaults to NO. Defines whether to add the definition_12_063 column to the gpkg_spatial_ref_sys system table, according to http://www.geopackage.org/spec/#extension_crs_wkt . The default is NO, unless the tile gridded coverage extension is used. With VERSION >= 1.4, a epoch column is also added. WKT strings in definition_12_063 will follow the WKT2:2015 standard when possible, but may use the WKT2:2019 standard for specific cases (dynamic CRS with coordinate epoch). This option generally does not need to be specified, as the driver will automatically update the gpkg_spatial_ref_sys table when needed, but it may be useful to create GeoPackage datasets matching the exceptions of other software or profiles (such as the DGIWG-GPKG profile).
METADATA_TABLES=[YES/NO]: (GDAL >= 3.8) Defines whether to add the metadata system tables. By default, they are created on demand. If NO is specified, they are not created, even if metadata is set. If YES is specified, they are always created.

Overviews

gdaladdo / BuildOverviews() can be used to compute overviews. Power-of-two overview factors (2,4,8,16,...) should be favored to be conformant with the baseline GeoPackage specification. Use of other overview factors will work with the GDAL driver, and cause the gpkg_zoom_other extension to be registered, but that could potentially cause interoperability problems with other implementations that do not support that extension.

Overviews can also be cleared with the -clean option of gdaladdo (or BuildOverviews() with nOverviews=0)

Metadata

GDAL uses the standardized gpkg_metadata and gpkg_metadata_reference tables to read and write metadata.

GDAL metadata, from the default metadata domain and possibly other metadata domains, is serialized in a single XML document, conformant with the format used in GDAL PAM (Persistent Auxiliary Metadata) .aux.xml files, and registered with md_scope=dataset and md_standard_uri=http://gdal.org in gpkg_metadata. In gpkg_metadata_reference, this entry is referenced with a reference_scope=table and table_name={name of the raster table}

It is possible to read and write metadata that applies to the global GeoPackage, and not only to the raster table, by using the GEOPACKAGE metadata domain.

Metadata not originating from GDAL can be read by the driver and will be exposed as metadata items with keys of the form GPKG_METADATA_ITEM_XXX and values the content of the metadata columns of the gpkg_metadata table. Update of such metadata is not currently supported through GDAL interfaces ( although it can be through direct SQL commands).

The specific DESCRIPTION and IDENTIFIER metadata item of the default metadata domain can be used in read/write to read from/update the corresponding columns of the gpkg_contents table.

You can set the CREATE_METADATA_TABLES configuration option to NO to avoid creating and filling the metadata tables.

IMAGE_STRUCTURE metadata item

注釈

Implementation details, normally transparent to GDAL users, but useful for other implementations.

Starting with GDAL 3.6.1, the following optional metadata items can be read and write into the IMAGE_STRUCTURE metadata domain, in the <GDALMultiDomainMetadata> XML element:

BAND_COUNT=1, 2, 3 or 4. Applies only for Byte data. Set when creating a dataset so that GDAL knows the number of bands when reopening it.
COLOR_TABLE={{r0,g0,b0,a0},...{r255,g255,b255,a255}}. Applies only for Byte data and a single band dataset. Set when creating a dataset from a source dataset that has a color table.
TILE_FORMAT=PNG/PNG8/PNG_JPEG/JPEG/WEBP. Set when creating a dataset so that GDAL knows the tile format when reopening it, for updates.
NODATA_VALUE=integer between 0 and 255. Applies only for Byte data.

Example:

INSERT INTO gpkg_metadata VALUES(
    1,
    'dataset',
    'http://gdal.org',
    'text/xml',
    '<GDALMultiDomainMetadata><Metadata domain="IMAGE_STRUCTURE"><MDI key="BAND_COUNT">1</MDI><MDI key="NODATA_VALUE">255</MDI></Metadata></GDALMultiDomainMetadata>')
);
INSERT INTO gpkg_metadata_reference VALUES(
    'table','my_raster_table',NULL,NULL,'2022-11-09T18:44:59.723Z',1,NULL);

Level of support of GeoPackage Extensions

(Restricted to those have a raster scope)

Extensions
Extension name	OGC adopted extension ?	Supported by GDAL?
Zoom Other intervals	Yes	Yes
Tiles Encoding WebP	Yes	Yes
Metadata	Yes	Yes
WKT for Coordinate Reference Systems (WKT v2)	Yes	Partially, since GDAL 2.2. GDAL can read databases using this extension. GDAL 3.0 brings support for the WKT v2 entry.
Tiled Gridded Coverage Data	Yes	Yes, since GDAL 2.3 (GDAL 2.2 supported a preliminary version of this extension)

Examples

Simple translation of a GeoTIFF into GeoPackage. The table 'byte' will be created with the tiles.
```
gdal_translate -of GPKG byte.tif byte.gpkg
```

Translation of a GeoTIFF into GeoPackage using WebP tiles

gdal_translate -of GPKG byte.tif byte.gpkg -co TILE_FORMAT=WEBP

Translation of a GeoTIFF into GeoPackage using GoogleMapsCompatible tiling scheme (with reprojection and resampling if needed)
```
gdal_translate -of GPKG byte.tif byte.gpkg -co TILING_SCHEME=GoogleMapsCompatible
```

Building of overviews of an existing GeoPackage, and forcing JPEG tiles

gdaladdo -r cubic -oo TILE_FORMAT=JPEG my.gpkg 2 4 8 16 32 64

Addition of a new subdataset to an existing GeoPackage, and choose a non default name for the raster table.

gdal_translate -of GPKG new.tif existing.gpkg -co APPEND_SUBDATASET=YES -co RASTER_TABLE=new_table

Reprojection of an input dataset to GeoPackage

gdalwarp -of GPKG in.tif out.gpkg -t_srs EPSG:3857

Open a specific raster table in a GeoPackage
```
gdalinfo my.gpkg -oo TABLE=a_table
```

Raster SQL functions

The raster SQL functions mentioned at ラスタ関連関数 are also available.

The gdal_get_layer_pixel_value() function (added in GDAL 3.7), variant of the generic gdal_get_pixel_value(), can be used to extract the value of a pixel in a raster layer of the current dataset.

It takes 5 or 6 arguments:

a string with the layer/table name
a band number (numbering starting at 1)
a string being "georef" to indicate that subsequent values will be georeferenced coordinates, or "pixel" to indicate that subsequent values will be in column, line pixel space
georeferenced X value or column number
georeferenced Y value or line number
resampling method among nearest (default), bilinear, cubic, cubicspline. Optional, added in GDAL 3.10

SELECT gdal_get_layer_pixel_value('my_raster_table', 1, 'georef', 440720, 3751320)
SELECT gdal_get_layer_pixel_value('my_raster_table', 1, 'pixel', 0, 0)
SELECT gdal_get_pixel_value('my_raster_table', 1, 'pixel', 0.5, 0.5, 'bilinear')  -- GDAL >= 3.10

Other notes

Development of raster support in the GeoPackage driver was financially supported by Safe Software.