DEMZREF

Description

Convert DEM elevation reference (Mean Sea Level <-> Ellipsoid)

Parameters

Name	Type	Length	Value range
Input: Input DEM channel *	Raster port	1 - 1	1 -
Output image channel: Output converted image channel	Raster port	0 - 1	1 -
Background Elevation Value	Float	0 - 1
Failed Elevation Value	Float	0 - 1
Input Elevation Reference	String	0 - 1	MSL | ELLIPS
Elevation Units	String	0 - 1	METER | FEET
Report	String	0 - 192	See parameter description

* Required parameter

Parameter descriptions

Input: Input DEM channel

Specifies the channel number of the input elevation data to use.

Output image channel: Output converted image channel

Specifies the output channel to receive the converted image.

If the input (FILEDEM) and output (FILO) files are the same, and the output channel (DBOC) is identical to the input channel (DBEC) or if the specified output channel already exists, the new output overwrites the specified channel.

If FILO does not exist, a new file is created. In this case, DBOC should be defaulted.

If FILO points to a valid writable file and DBOC is defaulted, a new output channel is created.

Background Elevation Value

Specifies the background elevation value of the input and output digital elevation model (DEM). When the empty DEM file is first created, it fills the entire DEM channel with the BACKELEV value. In the final DEM file, this value indicates areas that have no stereo images from which to extract elevation values. It is recommended that this value be set as the NO_DATA_VALUE metadata tag in the output file.

Select a value that is different from FAILVALU (Failed Elevation Value) and that is not a valid extracted elevation value for the area. For example, setting BACKELEV to 0 in a coastal area is a poor choice because a valid extracted elevation can match this value.

Failed Elevation Value

Specifies the value given to pixels for which the generation of elevation values failed. This value should be outside the range of valid elevation values. The failure value identifies the areas that can be interpolated and filled.

Input Elevation Reference

Specifies the original (input source) vertical reference for elevation values in the DEM.

Elevation Units

Specifies the units of the elevation values stored as pixel values in the input DEM.

ELEVUNIT defaults to ELEVATION_UNITS metadata tag if it exists; otherwise, it defaults to METER. The ELEVATION_UNITS metadata tag is created or updated after the conversion is complete.

Report

Specifies where to direct the generated report.

Available options are:

• LOG: generates a report on the terminal (default)
• <modulename.RPT>: appends a report to the module's RPT file
• DISK: generates a report on file "IMPRPT.LST"

Details

The module DEMZREF converts a raster DEM from Ellipsoid to Mean Sea Level, or vice-versa, using a global geoid model.