====== The DEM Menu ======

===== Introduction =====

A Strabo project can contain a DEM, a set of height measurements forming a Digital Elevation Model.

{{dem_menu.gif?476x172&nolink}}

The DEM is always part of a saved project.\\  Here are some functions to handle different DEM sets.

===== Open New DEM Set ... (Clear Existing DEM) =====

The purpose of this method is to clear the existing DEM set in the project and replace it by another DEM.\\  After selecting this menu function, run through the following steps:

    - A file selection box will popup.
    - Select a file containing a DEM. \\  This can be any text file containing a set of XYZ points.\\  This file can be a clean 'XYZ' file, or an 'QXYZ' file. With 'Q' standing for a quality factor.
    - Press the 'Open' button.
    - The newly selected DEM set will replace the actual Project's DEM file.

===== Add another DEM... =====

With this method, you can put together different DEM sets.\\  Run through the following steps:

  - A file selection box will popup to select a DEM file.
  - Press the 'Open' button.
  - The content will be appended to the DEM of the actual Strabo project.

===== Clear DEM =====

This function obviously clears the DEM in the actual project.

===== Save DEM As ... =====

Normally the DEM is stored together with the Strabo Project, which saves also other project information. (see [[..:project:Save_the_project|Saving the Project]])\\  With this function you can save the DEM to another location using a File Selection box.

When the DEM is generated automatically, all created DEM points get a quality factor. \\  The 'Save DEM As' function will, as well the 'Save Project' function, save these quality values in the Project files.

  - Select an absolute path and a filename using the Fileselection box that will popup.
  - Press the 'Save' button.

===== Save Restricted to the Overview... =====

With this method you can save a part of the DEM, namely the part restricted to the view extent of the OrbitGIS viewer.\\  Run through the following steps:

  - Zoom in at the requested scale to restrict the DEM area.
  - Select the menu function.
  - Select a filename and directory using a file selection.
  - Press the 'Save' button
  - Only the DEM points within the Orbit overview extent will be saved in the file, with available quality factor.

===== Save DEM (XYZ only)... =====

This method saves the complete DEM: only X, Y and Z coordinates of the DEM points will be saved, without any quality factor.

  - Select an absolute path and a filename in the Fileselection box.
  - Press the 'Save' button.