====== Stereo Viewer : DEM Viewer ======

The DEM Viewer is only available in the Softcopy package and is started in the same way as [[start|the other viewers]] by pressing the 'Show DEM Module' in the popup menu.

It's main function is to measure a DEM manually.

Clicking on the 'OrbitGIS Interactive' viewing panel with the right mouse button will show the next popup menu:

{{startup_dem_using_popupmenu.gif?706x445&nolink}}

Select the 'Show DEM Module' to start the next DEM Viewer:

{{dem_viewer.gif?541x449&nolink}}

The menu functions [[..:stereo:Using_the_3D_Explorer#View and Option menu in Stereo Explorer|'View' and 'Options']] are the same as described in the paragraph on Common Features in Stereo Viewers chapter.

===== Introduction: =====

The purpose of the DEM Module is the measurement of height points.

This module provides for:

  - the random measurement of DEM points
  - the measurement of DEM points on a predefined grid

These methods are both manual, and therefore don't add a quality factor to the measured DEM point.

==== Random Measurement: ====

Follow the next steps to measure a DEM point:

  - Put the floating mark on the ground using the scroll mouse button as described in [[..:stereo:Using_the_3D_Explorer#Moving the floating mark|'Moving the Floating Mark'.]]
  - Measure the height value by pressing the {{imagepoint_measure.gif?20x20&nolink}} button.\\ The XYZ point will be added to the Project DEM set. \ A small cross will be drawn in the stereo viewer.

Follow the next steps to delete a DEM point:

  - Put the floating mark in the neighborhood of the DEM point you want to delete as described in [[..:stereo:Using_the_3D_Explorer#Moving the floating mark|'Moving the Floating Mark'.]]
  - Press the {{imagepoint_delete.gif?20x20&nolink}} button to make the deletion effective.

==== Measurement on a grid: ====

  - The grid size is defined in '[[..:project:Step_A_Project_Settings]]' of the Project wizard.
  - Pressing the arrow icons moves the floating mark to the next grid point in the direction of the arrow.
  - Put the floating mark on the ground using the scroll mouse button as described in [[..:stereo:Using_the_3D_Explorer#Moving the floating mark|'Moving the Floating Mark'.]]
  - measure the height value by pressing the {{imagepoint_measure.gif?20x20&nolink}} button.\\ The XYZ point will be added to the Project DEM set.\\ A small cross will be drawn in the stereo viewer.


==== Save DEM: ====

Pressing the save button saves the project's DEM in '{Projectname}.sdp'.