Dear Damien, In Chimera version 1.4 (daily builds) there is a quality option in the Lighting tool (under Tools... Viewing Controls). Depending on your machine, you may be able to set the "quality" to "glossy" -- this will make surfaces of all kinds look much smoother without increasing the number of triangles. My knowledge of how it works is a little fuzzy, but I thought it somehow uses different normals all over the surface instead of just one normal for each triangle. The "glossy" option also turns on angle-dependent transparency. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/sideview.html#lighting. Glossy lighting was discussed in a little more detail in these recent messages: <http://www.cgl.ucsf.edu/pipermail/chimera-users/2009-June/004031.html> <http://www.cgl.ucsf.edu/pipermail/chimera-users/2009-June/004032.html> If the main reason for your question is wanting to make the surfaces look better, glossy lighting should suffice... as long as you can use a computer on which it is available. I don't know anything about getting the normal information out of Chimera (and the person who implemented glossy lighting is on vacation right now). I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html On Jul 2, 2009, at 3:20 AM, Damien Larivière wrote:

Dear Chimera team,

I have open in Chimera a VRML file containing multiple copies of the FtsZ protein.

The VRML file does not contain the smooth groups so that, at display, triangles appear at the surface of the proteins as shown in the attached image.

I would like to get the surface smooth but not by increasing the number of triangles.

Is there a way in Chimera to recalculate the normals as it can be done in 3DSMax for instance?

My best regards,

Damien