Parent Topic: IWORKS

DEM Editing

The DEM (Digital Elevation Model) Editing panel contains functions for modifying DEM data. The editing functions are especially useful in cleaning up elevation models which have been automatically extracted from satellite or airphoto stereo pairs (for example, from the EASI/PACE programs SDEM and ADEM).

In ImageWorks, the user can specify any data type for the DEM channel. A 16-bit signed integer channel (as opposed to a 32-bit real channel) is recommended since DEM files tend to be large and require a large amount of memory while being edited.

In OrthoEngine, DEM data is usually 16-bit signed integer data which has been read into a 16-bit signed integer channel. The initial Image/DEM viewing window size is 512 pixels by 512 lines. When the Image and/or DEM channels are loaded, the zoom scale is set to 1:1 in the viewing window so that a 512 x 512 window of the original data shows up in full resolution. At the bottom of the viewing window, various values are displayed. This includes the image X and Y file coordinates, the elevation of the (X,Y) position in the DEM channel, and the Grey Level of the (X,Y) position in the Image channel, if one is loaded.

A set of graphical editing tools is provided, enabling the user to perform the following functions:

creating editing masks
interpolating elevations to cover areas with no elevation information
filtering out `noisy' elevation points
smoothing out irregularities to create a more pleasing elevation model
setting areas (such as lakes) to constant values

In ImageWorks, the DEM Editing panel can be invoked by selecting the ``DEM...'' option from the ``Edit'' pulldown menu.

In OrthoEngine, the DEM Editing panel can be invoked from the DEM processing step.

The DEM Editing panel has five sections each of which is described below.

Parent Topic: IWORKS
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