odd glare when volume rendering

hello, I am getting an odd glare when I use solid rendering in VolumeViewer - it is orientation dependent, which makes me think it has to do with lighting? I am using build 2416; is it possible to forward a screenshot to the list? thanks, -- ------------------------------------------------------------- Jeff Triffo Auer Group, Donner Lab, Lawrence Berkeley National Laboratory Raphael Group, Bioengineering Department, Rice University Medical Scientist Training Program (MSTP), Baylor College of Medicine phone (Berkeley): 510-486-7940 fax (Berkeley): 510-486-6488

Hi Jeff, You can send an image to chimera-users. Messages over 40 Kbytes have to await approval before posted though. Solid rendering has no directional lighting as you can verify changing the light source direction using Tools / Viewing Controls / Lighting. The default solid rendering mode uses OpenGL 2D textures stacked up along the data axis (x,y, or z) most in line with your view. You probably are seeing artifacts related to that. You can try switching off "Solids using 2D textures" in the volume dialog "Solid rendering options" panel. With a high-end graphics card that will use 3-D textures that don't have as many artifacts. If your graphics card does not support 3D textures you will just see an outline box with no data. Tom

you are right, I now see nothing (must not support 3D textures) and the display update is real slow, but the same glare persists. here are a few screenshots (awaiting approval); they are at a few different orientations to show dependence. the two 'with' and 'without2D' textures show same orientation with that option toggled on/off. the rendering disappears, but the glare remains. also, if relevant, most of the volume is empty space (zeros) - the only data is along the diagonal of the box in a thin strip. I had not had this problem before with similar data in previous versions of Chimera (thin strip in volume of mostly zeros or otherwise), prompting me to ask. I don't think I had tried to volume render since I installed this version (2416) a while back; could this be due to a change between versions? thanks, -Jeff Thomas Goddard wrote:
Hi Jeff,
You can send an image to chimera-users. Messages over 40 Kbytes have to await approval before posted though.
Solid rendering has no directional lighting as you can verify changing the light source direction using Tools / Viewing Controls / Lighting.
The default solid rendering mode uses OpenGL 2D textures stacked up along the data axis (x,y, or z) most in line with your view. You probably are seeing artifacts related to that. You can try switching off "Solids using 2D textures" in the volume dialog "Solid rendering options" panel. With a high-end graphics card that will use 3-D textures that don't have as many artifacts. If your graphics card does not support 3D textures you will just see an outline box with no data.
Tom
-- ------------------------------------------------------------- Jeff Triffo Auer Group, Donner Lab, Lawrence Berkeley National Laboratory Raphael Group, Bioengineering Department, Rice University Medical Scientist Training Program (MSTP), Baylor College of Medicine phone (Berkeley): 510-486-7940 fax (Berkeley): 510-486-6488

Hi Jeff, Looks weird. Does the "glare" rotate with the map or does it change shape as you rotate? If it changes shape that is a possible graphics driver bug because Chimera is just telling OpenGL to rotate the view and is not changing it in any other way. Could you check if you have "transparent background" turned on using menu Tools / Viewing Controls / Effects. Try turning it off if it is on. Another thing to try is an older version of Chimera. Tell me a version number where it has no glare. You could also provide me the map and I'll see if it happens on my machine. Tom
participants (2)
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Thomas Goddard
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William Jeffrey Triffo