ENVI Generate Anaglyph

The purpose of this program is to create a 3D anaglyph visualization of a single-band gray scale raster image created from or used in conjunction with digital elevation model (DEM) data. The anaglyph is generated for on-screen or small print visualization and the spatial size of the output raster is dictated by the resolution of the computer monitor. Consequently, the spatial size of the output anaglyph can be much smaller than the columns x rows of the input DEM or drape image. 

To install this program simply download the "Anaglyph.sav" program file and move this file into the appropriate ENVI software installation subfolder. For example, here are the viable folder locations on Windows:

ENVI Classic:

     C:\ProgramFiles\Exelis\ENVI##\classic\save_add\

ENVI5:

     C:\ProgramFiles\Exelis\ENVI##\extensions\

          or

     C:\Users\%username%\.idl\envi\extensions#_#\

Then restart the ENVI software and a new tool will be available:

ENVI Classic:

     Topographic >Generate Anaglyph

ENVI5:

     Toolbox/Extensions/Generate Anaglyph

The execution of this tool is fairly straightforward:

(1) Select input DEM.

(2) Select single-band gray scale image to drape over DEM, or optionally you can create a Shaded Relief or Slope image on-the-fly directly within this tool.

(3) Select either Nadir or Perspective viewing angle. If you select Perspective you can rotate and Preview the 3D visualization as a wire mesh.

(4) Select the Degree Parallax (default value is 2). A larger parallax will increase the amount of vertical exaggeration in the resulting visualization. However, if the parallax is too large it will make the viewer feel as if they are "going cross-eyed" and may cause them to "see double".

(5) Specify an output file on disk for the resulting anaglyph raster.

(6) Press the "Start" button and wait for processing to complete.

(7) Resulting output Anaglyph image should be automatically loaded into a new display window/view.

NOTE: Since anaglyph images are generated by taking a raster and shifting it to the left & right in the R,G,B channels the result is, by definition, a raw pixel-based raster. Even if the input DEM and drape image were georeferenced with spatial reference, the resulting anaglyph image does not inherit this coordinate system metadata because it is impossible to define where any given anaglyph pixel resides on the surface of the Earth.