SDO_GEOR_GDAL.dem

Format

SDO_GEOR_GDAL.dem(
     inGeoRaster     IN SDO_GEORASTER, 
     outGeoRaster    IN OUT SDO_GEORASTER, 
     processing      IN VARCHAR2 DEFAULT NULL,
     options         IN VARCHAR2 DEFAULT NULL,
     createOptions   IN VARCHAR2 DEFAULT NULL,
     metadataOptions IN VARCHAR2 DEFAULT NULL,
     colorDirectory  IN VARCHAR2 DEFAULT NULL,
     colorFileName   IN VARCHAR2 DEFAULT NULL, 
     openOptions     IN VARCHAR2 DEFAULT NULL);

Description

Processes an input Digital Elevation Model (DEM) to produce an output GeoRaster object that reflects specified processing and translation options.

Parameters

inGeoRaster

GeoRaster object, typically a Digital Elevation Model (DEM).

outGeoRaster

GeoRaster object to hold the result of the operation. Must be a valid initialized GeoRaster object. Cannot be the same GeoRaster object as inGeoRaster

processing

When specified, identifies the name of the DEM processing technique to apply:

aspect generates an aspect map.
color-relief generates a color relief map.
hillshade generates a shaded relief map.
Roughness generates a map of roughness.
slope generates a slope map.
TPI generates a map of Topographic Position Index.
TRI generates a map of Terrain Ruggedness Index.

options

When specified, identifies options for the GDAL translate operation. See the Usage Notes for a table of names and explanations of possible options parameter values.

Example: options => 'outputType=float32'

createOptions

When specified, identifies options specific to the output driver. Format 'name=value', with options separated by space. Example: "COMPRESS=JPEG-F GENPYRAMID=NN"

metadataOptions

When specified, assigns metadata values specific to the output driver. Format 'name=value', with options separated by space. Example: "TIFFTAG_POINTAREA=AREA"

colorDirectory

When specified, identifies the name of a directory object related to the file system directory where the input color table file is located.

colorFileName

When specified, identifies the base file name of a GDAL compatible color table file.

openOptions

When specified, identifies ptions specific to the input driver format. See the GDAL supported format list for details.

Usage Notes

The openOptions parameter possible keywords are listed in the following table.

Table 10-1 openOptions Parameter Possible Values for dem Operations

Keyword	Explanation
`alg`	Indicates whether to use the ZevenbergenThorne algorithm instead of Horn’s formula. Boolean type; default is `false`.
`altitude`	For `hillshade` processing only. Indicates the altitude of the light, in degrees (90 if the light comes from above the DEM, 0 if it is raking light).
`azimuth`	For `hillshade` processing only. The default value is 315. It should rarely be changed, because this is the value generally used to generate shaded maps.
`band`	Band number that identifies the DEM. Values start at 1 (the default).
`Combined`	For `hillshade` processing only. Indicates whether to compute combined shading, a combination of slope and oblique shading.
`computeEdges`	Indicates whether to compute values at raster edges or not. Boolean type; default is `false`.
`outputType`	Output pixel data type. Supported values are: `Byte`, `Int16`, `UInt16`, `UInt32`, `Int32`, `Float32`, `Float64`, `CInt16`, `CInt32`, `CFloat32` , and `CFloat64`. Example: `'outputtype=float64'` If this option is not specified, the input data type will be used. Check if the output format supports the data type in use.
`scale`	Indicates the ratio to multiply the vertical units. For example, use `scale=111120` if the vertical units are meters (or `scale=370400` if they are in feet) and need to be converted.
`Trigonometric`	For `aspect` processing only. Indicates whether to return the trigonometric angle instead of azimuth. `0deg` means East, `90deg` means North, `180deg` means West, and `270deg` means South.
`zeroForFlat`	For `aspect` processing only. Indicates whether to return 0 for flat areas with `slope=0`, instead of -9999.
`zFactor`	For `hillshade` processing only, indicate the vertical exaggeration.

For convenience, the arguments of the options parameter can also be entered in the same format as the GDAL gdal_dem command line tool. Example: ”-b 1 –scale 10”

Examples

The following example produces an aspect map from an input DEM.

DECLARE
  gr6 sdo_georaster;
  gr7 sdo_georaster;
BEHIN
  delete from imagery where id = 7;
  insert into imagery values(7, sdo_geor.init('dem_rdt',7))
         returning raster into gr7;
  select raster into gr6 from imagery where id = 6;
  sdo_geor_gdal.dem(inGeoRaster     => gr6,
                    outGeoRaster    => gr7,
                    processing      => 'aspect',
                    options         => 'outputType=float32');
  update imagery set raster = gr7 where id = 7;
  commit;
END;

10.1 SDO_GEOR_GDAL.dem