From: Rune Thomas Kidmose (
Date: Wed Mar 07 2018 - 09:49:40 CST


Lately I have been playing around with the very powerful tachyonL-optix rendering on relative big models (70S ribosome and 100S ribosomes) in complex scenes.

I prefer to do all my final movies and images from scripts, so I am also calling tachyonL-optix this way. However, I have noticed a big change in quality between what the interactive TachyonL-optix engine gives me (from GUI of course) and what I get from the internal tachyonL-optix engine via my script.

When I test in the GUI on large complex scenes ( movie of ribosome trajectories, a lot of glass, shadows, reflection and very large molecules etc) I have to let the interactive tachyonL-optix scene render for quite a while, to get everything looking smooth and nice. At that point I stop the render and save the image. When I do the exact same scene via the internal tachyonL-optix from scripts (but also from the GUI !) the end results is far from the same quality regarding smoothness and details. It applies the same materials, lightning view matrix display size etc. but the rendered image looks much worse.

I guess it is has something to do about how long time the image is allowed to render before being written as a file. Is there any way of increasing this time via an extra tachyon render command or flag I can state? Or is it something completely different that is the cause?

Regarding the hardware I test it on (if relevant) it is a dell linux workstation with dual GPU (quadro M5000 and nvidia 980TI) plenty of memory and 16 cores. I can add details if needed of course.

And I am using VMD 1.93 from ubuntu 16.04