[Chimera-users] OBJ files are exported too small and won't open on other programs.

[Elaine Meng]

Hi Josh,
The documentation for Chimera scene export explains the limitations of each format, including OBJ.

<http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/export.html>

OBJ exports only include surface models, so if you didn’t show a surface for your structure before exporting, the file won’t have anything in it.  They’re also single-color.  Given these OBJ-export limitations, you may want to use a different export format if possible.

Chimera doesn’t take OBJ files as input
<http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/filetypes.html>

…but you can check the OBJ file by opening it in ChimeraX (our next-gen program, also free download for noncommercial use).  I just tested exporting a surface for 4hhb from Chimera as OBJ format, and it opened fine in ChimeraX as a gray surface.   Compared to Chimera, the molecular surface calculation in ChimeraX is more robust, so you might want to take a look at using ChimeraX for exporting too.

ChimeraX <http://www.rbvi.ucsf.edu/chimerax/index.html>
…ChimeraX User Guide <http://rbvi.ucsf.edu/chimerax/docs/user/index.html>
…the formats it can save <http://rbvi.ucsf.edu/chimerax/docs/user/commands/save.html#formats>
…the formats it can read <http://rbvi.ucsf.edu/chimerax/docs/user/commands/open.html#formats>
-----
Elaine C. Meng, Ph.D.
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco

> On Aug 1, 2019, at 6:59 AM, Josh Moon <Josh.Moon at kzoo.edu> wrote:
> 
> Hello!
> 
> I am a relatively new and inexperienced user of Chimera.  I am having a difficult time working with obj files.  The Scenes I’m exporting as obj’s end up having a very small file size (67 bytes in one case) and are being processed very quickly.  The resulting file won’t open successfully on any program that should understand an obj. Stl’s are fine. 
>  
> Conversely, when I try to open an obj file into Chimera, it asks me to manually “Designate the File Type” as though it doesn’t know what to do with it.
>  
> Can someone please suggest what features I’m missing so that I can successfully export an OBJ?  I’m also interested in how best to handle color information.
>  
> Thank you!
> Josh