- Chimera-users - RBVI Mailing Lists

Re: [Chimera-users] transform coordinates of multiple volumes
by Elaine Meng 03 May '12

03 May '12

On Apr 27, 2012, at 9:26 AM, Ludovic Renault wrote: > Hi Elaine, > I have 120 or so 3d volumes (EM maps). They are all equivalent and are centered at the same position. > I would like to move each one of these 120 volumes by a specific value in terms of euler angles and shift (in pixels I assume). I can use the 'trAnsform coordinates' tool but then if I save the map, it is not saved with the new coordinates. > So > 1- How to (Or can I) save the new coordinates for each volume? > 2- Can I use command lines to automate the process for example by giving the command a text file with the specific coordinates for each volume? > > I did do the rotation with spider software, but the shifting doesn't work because the volume(s) go outside of the box. So if all the above is not doable, is it possible to increase the volumes boxe size in chimera, then I could use the shift function in spider? > > I hope I'm clear enough. > Thanks, > Ludovic Hi Ludovic, It is recommended to send Chimera questions to the chimera-users list (CC'd) -- I'm not the top expert on volumes, so others may have better answers! I think the shift in Transform Coordinates is not in pixels but in units of length. <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/transform/transfor…> How the volume grid units map to units of length can be viewed by using Features...Coordinates in the Volume Viewer menu. Chimera has commands for translation (move) and rotation (turn) in X,Y,Z coordinate systems, but I don't know of a command to apply Euler rotations. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/move.html> <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/turn.html> About saving a transformed map: The map formats don't include transformation information, so there is no way to save EXACTLY the same data, except transformed. However, you can resample the map onto a new grid, and then save the new map. The values at the new grid points are determined by interpolation, so there will be some (generally minor) data loss. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/savemodel.html#afterfitting> The resampling of one map onto the grid of another can be done with command "vop resample", for example: vop #1 resample onGrid #0 <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#resample> To save the new resampled volume to a file, you could use "File... Save Map as" in the Volume Viewer dialog or the command "volume" with its "save" option. However, I see that "vop resample" is most pertinent for saving a map that has been fitted to another. In your case you are simply transforming the map, so it is unclear on what grid you could resample. Maybe there is some way to make a "dummy" grid in the right place. Although "vop cover" extends a map, it assumes periodicity of that map, whereas I assume you want zeroes in the expanded parts. Perhaps expanding a map with zeroes could be done using "vop add" to add a dummy zero map to your data set of interest. Sorry I couldn't give a more complete solution, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco

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About resolution and origin
by Yuhong Li 02 May '12

02 May '12

Hi friends, Firstly, I was wondering how to know the resolution of my map since one day I opened volume viewer...tools...fit to segments. And I found that there displaying "density map resolution". So my question is whether that number is the correct resolution of my map? Secondly, in the volume viewer...corrdinates I can know the origin index, but how can I know the origin? These questions may seem to be stupid, but I just want to know. So hope to hear from you very soon! Best Wishes, Yuhong Lee

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changing map dimensions
by Elaine Meng 01 May '12

01 May '12

On Apr 30, 2012, at 6:56 PM, Yuhong Li wrote: > Hi Elaine, > Thanks for your help, now I've understood what those numbers mean. But I was wondering if you could tell me how I can change those gird points, such as change 88 66 94 to 94 94 94 or any cubic numbers ? > Best Wishes, > Yuhong Lee > Hi Yuhong, Please send Chimera questions to chimera-users(a)cgl.ucsf.edu instead of directly to me. Those numbers are the size of your input data file, so I'm not sure what you mean. You can't just change the numbers arbitrarily. It is possible to make a new data set by cutting off part of the original data set. One way to do that is to use the "volume" command to save a new map file, using the "saveSubregion" option to include only part of the original map. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/volume.html#output> However, it sounds like you want to make a new data set that is bigger than your original map. There is a "vop cover" command that will make a bigger map, but it assumes periodicity of the input map. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/vop.html#cover> If instead you wanted values of zero at the additional grid points, however, I don't know how to do that -- maybe the others have ideas. Elaine ---------- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco

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Just want atom distances
by Patricia LiWang 30 Apr '12

30 Apr '12

Hello users group, I don't want anything complicated-- I just want to get some rough distances between atoms. So I go to Tools Structure Analysis Distances A window comes up with an empty table. (No instructions on how to pick atoms) A search of the Chimera documentation tells me I have to Control-leftclick to pick two atoms But no matter how often I click and click and click, it never gives me anything. I can't get even one atom to show up in the panel, let alone two. The side chains are sitting right there, getting clicked away, with nothing happening in the table. I am reading so many similar documentation pages, and apparently there is a difference between "selecting" and "picking" So I figure I'll just use the command line. But the instructions don't even bother to tell you how to use the command line to get the distance between two atoms. There is documentation on how to get distances between something and a "plane". Why do they make this so hard? Surely this is the main "simple" thing people want to do with this program. Would someone please tell me how to Pick or Select or Whatever two amino acids (any atom in them would be fine) and get a distance? Or better yet, please tell me the exact command line command I can use to get the distance between Asparate 234 carboxyl oxygen and Aspartate 295 carboxyl oxygen, both from chain "G"? Thanks! Patti ---------------------------------------------------------------------------

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Measure contact between copies of the same map
by Giovanni Cardone 30 Apr '12

30 Apr '12

Hi, I can use the tool measure contactArea on the surface models of two different maps, but I can not make it work when using it on two copies of the same map: no matter how much I move one map with respect to the other, the first surface listed in the command line will always be entirely colored in red (using offset 0). It looks like the command ignores the transformation. Is this the expected behavior? I can work around it by resampling the maps after the transformation (vop resample # onGrid #), but I liked more the idea of doing the measure without this additional step. Tested it with the latest alpha version 1.7 (build 36320). Thank you, Giovanni

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Contour mapping
by Nikolay Igorovich Rodionov 30 Apr '12

30 Apr '12

Hi all, I was wondering if anyone could help me create an accurate contour map based on surface charge. I've tried rendering my molecule by charge, then using the surface clipping, capping, and the color zone tools. However, the coloring varies based on how I orient the plane. Does anyone know a better and more accurate way to creating a contour map? Nikolay Rodionov

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gaussian filter
by Mike Strauss 30 Apr '12

30 Apr '12

Hi, I've been using the gaussian filter for a number of years to help me display my noisy data. I'd like to understand what it's doing a bit better, and so I need help with the following code: ijk_linewidths = map(lambda step: linewidth / step, g.step) what is the resulting length of ijk_linewidths? I can't seem to figure out what type of data type g.step is. Is it a feature of the image itself, or where does it come from? Best Regards, mike

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About volume viewer in chimera 1.6.1
by Yuhong Li 30 Apr '12

30 Apr '12

Dear Chimera developers, Hi! I am a student from Sun Yat-Sen University. I recently began using the Chimera for my study, but I have a problem about how to read the displayed information in volume viewer. Here I attach a picture and inside the picture there are two places I've point out with arrows which represent two different map files in mrc fornat. Now I was wondering if you could spare some time to explain it to me that what do those different numbers mean? Hope to hear from your reply in very soon. Best Wishes, Yuhong Lee

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addaa command
by Mahendra B Thapa 27 Apr '12

27 Apr '12

Dear chimera users, I also added an amino acid residue at the N-terminus of a small protein following the posting: [Chimera-users] Using addaa at the N-terminus?*[ posted date:Fri Sep 30 10:36:31 PDT 2011]* The residue is added at the n-terminus but the added residue is not connected to rest of the protein structure in the graphical display [i.e, a little gap between the added residue and the rest of the protein at N-terminus]. Is this due to wrong command ? Thanks, Mahendra Thapa Graduate student Department of Physics University of Cincinnati, OH

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Per model clipping not working ?
by Damien Larivière 27 Apr '12

27 Apr '12

Dear all, I try to use the Per-Model clipping tool but this error is returned, whatever the PDB file: Model cannot currently be clipped [no valid bounding box] Do I make something wrong? I use Chimera version 1.6.1 (build 35849). My configuration is Windows 7 64bits, ATI Mobility Radeon HD5650. Many thanks for your help! Damien

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