Transparency with soft lighting

Hi everybody, I’m writing because I saw in a YouTube video that you used “soft” lighting with transparency for an EM density map. It looked great. I can’t find the video again or the right documentation on how to do it. There was some command with the lighting that you typed in the command line. Do you know what I’m talking about? Thanks, Scott Scott Stagg Professor Institute of Molecular Biophysics Department of Biological Sciences Florida State University Tallahassee, FL 32306-4380 w: 850-645-7872 f: 850-644-7244 sstagg@fsu.edu https://www.stagglab.com

Hi Scott, It is easy to turn on soft lighting, either use command "light soft" or just click the icon that looks like a sugar cube in the toolbar across the top. See lighting help: <https://rbvi.ucsf.edu/chimerax/docs/user/commands/lighting.html> There are several ways to make the EM isosurface transparent, e.g. by clicking the color square in the Volume Viewer dialog and using the system color editor (which generally has some kind of opacity control), or selecting the isosurface in the graphics window (Ctrl-click) and using menu Actions... Surface... Transparency... [ %value] Volume Viewer: <https://rbvi.ucsf.edu/chimerax/docs/user/tools/volumeviewer.html> selection: <https://rbvi.ucsf.edu/chimerax/docs/user/selection.html> Actions menu: <https://rbvi.ucsf.edu/chimerax/docs/user/menu.html#actions> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco
On Feb 10, 2023, at 6:48 AM, Scott Stagg via ChimeraX-users <chimerax-users@cgl.ucsf.edu> wrote:
Hi everybody,
I’m writing because I saw in a YouTube video that you used “soft” lighting with transparency for an EM density map. It looked great. I can’t find the video again or the right documentation on how to do it. There was some command with the lighting that you typed in the command line. Do you know what I’m talking about?
Thanks, Scott

Hi Scott, I'm not sure what video that is in. But there is some obscure ChimeraX magic involved. If you use the "soft" lighting (shadows cast from all directions) with a transparent surface it looks horrible because transparent surfaces by default don't cast shadows in ChimeraX. The reason for that default is often you are showing a molecule inside a transparent surface and then the molecule is dark (black actually) and hard to see. Because the transparent surface doesn't cast shadows it does not shadow itself so you don't get any of the darkened cavities that help 3D appearance. To make transparent surface cast shadows use ChimeraX command material transparentCastShadows true If you have an atomic structure (#2) inside the surface it will look black (shadowed), but you can tell it not to accept shadows lighting model #2 multishadow false The model inside can look pretty horrible and flat with soft lighting and you might try full lighting that adds a spot light, and also use silhouette edges. Here is an example of all these tricks. open 1080 from emdb light soft volume level 0.6 open 1grl preset cylinders fitmap #2 in #1 transparency #1 80 material transparentCastShadows true lighting model #2 multishadow false graphics silhouettes true set bgColor white light full Thanks for asking! Tom Opaque map, and transparent map, and transparent map with shadows with soft lighting.  Atomic model is dark inside transparent map casting shadows. Can make atomic model not accept shadows. "Full" lighting instead of soft can make the atomic look less flat. 
On Feb 10, 2023, at 6:48 AM, Scott Stagg via ChimeraX-users <chimerax-users@cgl.ucsf.edu> wrote:
Hi everybody,
I’m writing because I saw in a YouTube video that you used “soft” lighting with transparency for an EM density map. It looked great. I can’t find the video again or the right documentation on how to do it. There was some command with the lighting that you typed in the command line. Do you know what I’m talking about?
Thanks, Scott
Scott Stagg Professor
Institute of Molecular Biophysics Department of Biological Sciences Florida State University Tallahassee, FL 32306-4380 w: 850-645-7872 f: 850-644-7244 sstagg@fsu.edu https://www.stagglab.com
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participants (3)
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Elaine Meng
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Scott Stagg
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Tom Goddard