[MINC-users] Details about cortical surface object file

[Simon Fristed Eskildsen]

Hi Ed,
The layout of an .obj (MNI style) file is:

Vertex header (Ex. "P 1.0 1.0 1.0 100 1 180098")
Vertex coordinates
Vertex normals
Polygon header (Ex. "359544 2")
Vertex/triangle colours
Polygon indices (defines the start of each polygon in the vertex indices 
below)
Vertex indices (defines each polygon)

Here is a simple cube in triangle polygon format with red and blue 
vertex coloring:

P 0.3 0.3 0.4 10 1 8
0 0 0
0 0 100
0 100 0
0 100 100
100 0 0
100 0 100
100 100 0
100 100 100

-0.666667 -0.333333 -0.666667
-0.333333 -0.666667 0.666667
-0.408248 0.816497 -0.408248
-0.816497 0.408248 0.408248
0.408248 -0.816497 -0.408248
0.816497 -0.408248 0.408248
0.666667 0.333333 -0.666667
0.333333 0.666667 0.666667

12 2
0.0 0.0 1.0 1
0.0 0.0 1.0 1
0.0 0.0 1.0 1
0.0 0.0 1.0 1
1.0 0.0 0.0 1
1.0 0.0 0.0 1
1.0 0.0 0.0 1
1.0 0.0 0.0 1

3 6 9 12 15 18 21 24 27 30 33 36

0 1 3 0 3 2 2 3 7 2 7 6 6 7 5 6 5 4 4 5 1 4 1 0 1 5 7 1 7 3 0 2 6 0 6 4

See also http://wiki.bic.mni.mcgill.ca/index.php/ObjectFiles
The description there lacks the color information though.

Simon

Ed Gronenschild wrote:
> Hi,
> 
> I would like to import the output file (extension .obj) of  
> cortical_surface
> into a private Mac OS X application. Is there a description of this file
> and how to read and use it. Of course, I could go through the source
> files of Display, but that would take me a lot of time.
> 
> Regards,
> Ed
> _______________________________________________
> MINC-users at bic.mni.mcgill.ca
> http://www.bic.mni.mcgill.ca/mailman/listinfo/minc-users