View Full Version : 3DS format - what/where are the units?

04-02-2016, 05:14 AM
I have become a little bit familiar with the 3DS file format (based on this description (http://www.martinreddy.net/gfx/3d/3DS.spec), which is pretty good). However, it doesn't seem to make any reference to the measurement units.

I have reason to think that they are variable, because if I display existing 3DS files together they may be at totally the wrong size relative to one another.

I have reason to think that there is a units setting stored in the file, because SketchUp Pro's documentation says: " If SketchUp doesn’t detect a units value in the 3DS file, SketchUp imports the 3DS file in inches". https://help.sketchup.com/en/article/3000169-0

Does anyone happen to know whether/where (i.e. in which chunk) the units can be found in a 3DS file?

04-04-2016, 02:28 AM
To answer my own question somewhat after further Googling, there is the master scale chunk (0x0100). As the name suggests this is a scale factor applicable to the file contents. Ignoring this may be partly responsible for objects appearing at the wrong size.

I cannot find any chunk that specifies the units and I guess there isn't one. If that is the case, the Sketchup documentation as quoted above is somewhat misleading.