DEMWRIT

Description

DEMWRIT writes 16-bit elevation data from a PCIDSK file to one or more United States Geological Survey (USGS) digital elevation model (DEM) format files. DEMWRIT writes only ASCII format, 7.5-minute (30m resolution, 1:24,000 scale) DEM data; it does not write binary (unformatted) or 1-degree DEM data.

Parameters

Name	Type	Length	Value range
DEM File Name *	String	1 -
Input: DEM Layer: Input raster channel or layer *	Raster port	1 - 1

* Required parameter

Parameter descriptions

DEM File Name

Specifies the file name (without a file name extension) of the created DEM files. The DEM files are created automatically. You must specify a file name.

Depending on the size and location of the DEM data, more than one DEM file may be written. The DEM files are created and ordered from right to left (west to east) and from top to bottom (north to south). Each DEM file covers a 7.5 by 7.5 minute area. The DEM file names use the 'filename.m-n' format, where m and n specify the row and column number.

Input: DEM Layer: Input raster channel or layer

Specifies the input image channel from which the DEM data is read. Although the input channel can be any type, DEM data is always generated as signed 16-bit values.

Details

DEMWRIT writes 16-bit elevation data from a PCIDSK file to one or more United States Geological Survey (USGS) digital elevation model (DEM) format files. DEMWRIT writes only ASCII format, 7.5-minute (30m resolution, 1:24,000 scale) DEM data; it does not write binary (unformatted) or 1-degree DEM data.

DEMWRIT transfers image data to a specified image channel (DBIC/DEM Layer) to a USGS DEM format text file on a disk. The PCIDSK file must be georeferenced using UTM coordinates with a zone number (using GEOSET).

DEM files are created and ordered from right to left (west to east) and from top to bottom (north to south). Each DEM file covers a 7.5-minute longitude by 7.5-minute latitude area. The file name extension for the DEM file specifies its location in the grid of new DEM files (created by DEMWRIT) as follows:

 +-------------------------------+
 |  1-1  |  1-2  |  ...  |  1-n  |
 +-------------------------------+
 |  2-1  |  2-2  |  ...  |  2-n  |
 +-------------------------------+
 |  ...  |  ...  |  ...  |  ...  |
 +-------------------------------+
 |  m-1  |  m-2  |  ...  |  m-n  |
 +-------------------------------+

The grid of DEM files may not be perfectly rectangular. Some files along the first or last row or column may be missing, depending on the location of the input window from the PCIDSK image file.