[chimerax-users] Color palettes for planes and solid data?

[Tom Goddard]

Hi Oli,

  There is no capability to automatically use a palette and min/max range of map values that sets the levels and colors.  That might be useful although when I have done this by hand I think equally spaced colors rarely produces what I want.  The cryosparc image you attached is a good example of the color spacing not producing a very informative view.  At any rate, if you want this feature in ChimeraX use the Help / Report a Bug… menu entry which is also for requesting features.

  I just tried setting the map threshold below the lowest value in the map and clipping in Chimera 1 and it only clips a cube for me.  So I’m not sure what you mean when you say that works in Chimera 1.

  The streaks when you color the clipped and capped surface are because the cap is composed of triangles and only the vertices of the triangles are colored and the triangles are very long and skinny.  Read about the Surface Capping mesh subdivision option in Chimera 1 if you want more explanation of it.  ChimeraX does not yet support the cap subdivision, but if you follow my previous suggestion it is an alternative method that can work.

	Tom


> On Feb 28, 2019, at 12:31 PM, Oliver Clarke <olibclarke at gmail.com> wrote:
> 
> Hi Tom,
> 
> Yes I know it is possible to do manually, thank you, but it requires quite a lot of futzing about with brightness/color pairs to get nice looking results. I was wondering if it would be possible to add support for palettes, with color thresholds automatically distributed between a minimum and a maximum, so that one can for example color a map slice with a rainbow palette between a minimum and a maximum density value (e.g. as per the density slices from cryosparc that I attached to the previous email).
> 
> Re the cube, I set the threshold to -10 so that when I clip the map, it exposes a face that I can color by density value. I do this in Chimera and it works as expected without altering anything, here I just see streaks. I’m still unclear why I just see streaks on the clipped face no matter the threshold - this doesn’t seem to be the intended behavior?
> 
> Oli
> 
>> On Feb 28, 2019, at 3:06 PM, Tom Goddard <goddard at sonic.net> wrote:
>> 
>> Hi Oli,
>> 
>> To set the colors of different map values use the volume command
>> 
>> 	volume #1 level 0,0 color white level 10,.9 color blue level 70,1 color green
>> 
>> This says map value 0 has brightness 0 and color white, map value 10 has brightness 0.9 (on a 0 to 1 scale) and color blue, map value 70 has brightness 1 and color green.  That is for using the “volume” or “plane” style as shown in the volume viewer panel.
>> 
>> When you instead try to color a clipped map surface, your second screenshot has the surface threshold set to -10 while your map values range -.1 to .15 so you see just a cube surface — not sure what you are doing that for.    In your third screen snapshot it looks better, but the colors are streaks on the clipped surface because the cap surface mesh subdivision is not fine.  In Chimera you can set the cap subdivision in the Surface Capping dialog, but there currently is no control of the cap mesh subdivision in ChimeraX.  Instead you could just crop the map either setting its bounds with the volume command “region” option or easier by using the crop mouse mode.  Then the face of the cropped box will use a mesh that matches the map resolution and coloring should be ok.
>> 
>> 	Tom
>> 
>> 
>>> On Feb 28, 2019, at 11:35 AM, Oliver Clarke <olibclarke at gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> Would it be possible to add support for more convenient coloring of solid representation data and planes of density maps? E.g. by specifying a color palette? Apologies if this already exists and I’m just not finding it!
>>> 
>>> I would like to be able to make nice looking slices of a density map, without surface contours, colored by density value (e.g. attached). This can be a good way of showing disordered regions of a EM reconstruction.
>>> 
>>> Currently, when a density map is loaded as a plane or solid represntation in Chimera, there is no way to automatically assign a predefined palette, and the defaults do not convey much information (at least for typical EM maps - example attached).
>>> 
>>> Also, when I attempt another way to do this, coloring the surface by map value and then clipping the surface, the results are odd, unlike in Chimera (see attached at different contours).
>>> 
>>> Cheers
>>> Oli
>>> 
>>> <Screen Shot 2019-02-28 at 2.34.47 PM.png><Screen Shot 2019-02-28 at 2.32.03 PM.png><Screen Shot 2019-02-28 at 2.25.00 PM.png><Screen Shot 2019-02-28 at 2.26.03 PM.png>
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>> 
> 
>