Each raster layer in a GDB database can have associated metadata, which is a set of string name and value pairs. An example is the
NO_DATA_VALUE metadata field. If metadata are provided, the name or tag is NO_DATA_VALUE and the value is treated as a special
raster image value, which is a no-data or missing-data value.
The following metadata tags are predefined for raster layers:
- DEFAULT_PCT_REF: The default PCT segment that displays an image in pseudocolor mode. If this entry is present, the image is
displayed in pseudocolor mode. Layer-reference syntax is described in the general metadata topic.
- DEFAULT_LUT_REF: The default LUT segment that is enhanced when an image is displayed. Layer-reference syntax is described
in the general metadata topic.
- SCALING_MIN: The default minimum value used for scaling an image channel to 8-bit for display purposes.
- SCALING_MAX: The default maximum value used for scaling an image channel to 8-bit for display purposes.
- NO_DATA_VALUE: The image value that indicates no data are available.
- ELEVATION_UNITS: This can be UNKNOWN (implicit default), FEET, or METERS. It is primarily used with elevation channels and
is UNKNOWN for non-elevation data.
- Class_n_Name: The short name for a theme class in a raster, where n is the class number. Preferably, the name should be
fewer than nine characters.
- Class_n_Desc: The longer description for a class in a raster.
- Class_n_Color: The color with which a particular theme class is displayed. The value is the color code, using the
RGB:rrr ggg bbb convention in the PCLColor class.
- ACQUISITION_DATE: The date and time in which an image is acquired. The format of the date is YYYY/MM/DD HH:MM:SS.