Selden's 3DS Billboard Meshes for Celestia

This technique is obsolete. Please use CMOD models instead, as described in billboard-cmod.html



1.0: The Flat Billboards.

2.0: Using the Billboard.

3.0: Problems with the Flat Billboard.

  1. This billboard model file cannot be read by 3D modelling programs unless the filename is 8.3 characters: 8 letters in the name of the file, 3 letters in the filetype, with a dot between them.

  2. A problem in Celestia is that Nebula models are not depth sorted. Instead, they are drawn on your screen in the order that you define them or in the order that Celestia happens to read their .DSC files. If overlapping Nebula models are declared in separate files. often they are drawn in the wrong order. When they overlap, you may not be able to see the one that is supposed to be closest to you. However, when you declare them in the same .DSC file, the model that is declared first in that .DSC file is drawn first, the second one is drawn on top of the first one, etc. At least that way you have some control over which ones are visible from a particular viewpoint.

  3. When you GoTo a Billboard object, Celestia often overshoots. I suspect the extreme aspect ratio (100x100x1) may be confusing it. If it thinks you are inside the object, various parts of the billboard get clipped off. In some cases, the whole thing will be invisible. Typing a "C" (center) or "T" (track) command and then backing away from it usually makes the billboard visible again.

  4. In the past, another difficulty for me has been getting the correct values for the Axis and Angle directives so the billboard is properly oriented and face-on to the line-of-sight from Earth. A recent insight made it much easier, though. The details are a little too complicated to go into right here. See 6.0: Aligning Pictures and Objects below.

4.0: Some Background.

5.0: Some Examples.

6.0: Aligning Pictures and Objects.

7.0: Some 3D Billboards.

8.0: Acknowledgements.


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A.0 Appendices.