[Chimera-users] Saving image and rendering

Tom Goddard goddard at cgl.ucsf.edu
Tue Jun 23 13:23:52 PDT 2009

Hi Ibrahim,

The glossy lighting quality setting is not available if your OpenGL 
driver and graphics card does not support shaders. Most graphics cards 
from the past few years support pixel and vertex shaders but older ones 
may not.


-------- Original Message --------
Subject: Re: [Chimera-users] Saving image and rendering
From: Ibrahim Moustafa
To: Eric Pettersen
Date: 6/23/09 12:26 PM
> Thanks Eric for the reply.
> Actually, I’m not using transparent surfaces. The image I tried to 
> make is a normal cartoon model.
> For the “glossy lighting” option: the button with the default “normal” 
> is inactive. How to turn it on? I could not figure it out.
> Thanks,
> Ibrahim
> On 6/23/09 1:24 PM, "Eric Pettersen" <pett at cgl.ucsf.edu> wrote:
>     On Jun 22, 2009, at 3:53 PM, Ibrahim Moustafa wrote:
>         Dear Chimera team,
>         Recently, I have some trouble saving images with POV-RAY
>         option “true”. The process of rendering is too slow (both on
>         the mac and windows version).
>         To give the feeling of how slow: rendering an image with 1700
>         lines takes 7 hrs (with quality 9 in pov-ray options) and 2
>         hrs (quality 5). I used to get the images rendered much faster
>         than that (with older versions; however, I’m not exactly sure
>         of when I started to see such a slow rendering behavior).
>     I'm guessing you're using transparent surfaces. We've made
>     improvements in the fidelity of translation of transparent colors
>     between Chimera and POV-Ray since the 1.3 release. In 1.3, the
>     transparent colors were much darker than they appeared in Chimera.
>     This change increases the rendering time because the amount of
>     supersampling that POV-ray performs depends on how much color
>     variation there is in the image and the new scheme provides a lot
>     more variation than its uniformly dark predecessor. One example I
>     tried produced slightly more than a factor of two in rendering
>     times between the 1.3 version and the current daily build.
>     Now, if you're rendering such a high-resolution image you don't
>     really need as much effort expended on each individual pixel as
>     you do for a smaller image. I find that if I increase the
>     "Antialias threshold" POV-Ray option from 0.3 to 1.0 then I get an
>     almost unchanged image in approximately the same time as as the
>     1.3 version required. You might even be able to go higher than
>     that and still get a good image.
>         There is another related problem but only with the windows
>         version: If I want to save an image, with depth cue, using the
>         fast mode (POV-RAY false), the image output lacks any depth
>         used in the model, with poor quality and darker than it should
>         be. Somehow, the camera orientation is messed. In addition,
>         the depth cue will be no longer available for the rest of the
>         session (I have to restart over again). To get the depth cue I
>         want, I need to turn the POV-RAY option “true”....but then too
>         slow to create a good figure.
>     I understand that Greg (who works on this code) recently made some
>     depth-cueing related bug fixes. Please try the very latest daily
>     build and see if you still get this problem. If you still do then
>     please use Help->Report a Bug to send us a bug report which will
>     automatically include detailed information about the system you're
>     using.
>         I’d appreciate any comment or explanation from Chimera people;
>         and what is the best way to overcome this problem?
>     An alternative to ray tracing is to turn on "glossy lighting"
>     (from the Lighting tab of the Side View). That may look good
>     enough for what you want and works with Chimera's non-raytraced
>     image saving.
>     --Eric
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