[Mne_analysis] mne_analyze coreg. on remote/virtual systems

Christopher Bailey cjb at cfin.au.dk
Tue Nov 4 03:26:39 EST 2014
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Dear List,

I would like to get input to the following issue Mengting Liu and I have been discussing off-list. Mengting's original question was:

Also, when I set fiducials in mne_analyze, the coordinates of  LAP/NASION/RAP will always have a 400 mm (which was definitly wrong)when I clicked on where I want to set the fiducials on the head surface, and I also am not able to type in the coordinates by hand, does it sound correct?

After some clarifications, we found out that the problem exists for him in a Virtual Machine, whereas I get the same behaviour while running mne_analyze through a VPN server on a remote machine. These two scenarios have in common that the host (VM or VPN server) does not have bare-metal access to the GPU (in Mengting's case AMD, in mine Nvidia), which means  that OpenGL calls are handled by the open-source Mesa-implementation.

(I originally suspected a lack of direct rendering support being the culprit, but this is not the case as Mesa can and will provide it in a VM setting.)

I wonder if any of the developers with access to the source code might be able to provide a clue as to which (OpenGL, I presume) call is being issued when the user clicks on the 3D view to indicate the position of a cardinal point? And whether there's a chance that might be altered to be Mesa-friendly (if indeed my analysis is correct...)?

I'm surprised that this issue hasn't been brought up before, as the use of VM's seems to be becoming more and more popular. If you have had success in doing co-registration in mne_analyze running in a VM, please let us know!

For completeness, here is the output of
glxinfo | grep -i "OpenGL "
run on a:

- VM with recent Ubuntu
OpenGL vendor string: VMware, Inc.
OpenGL renderer string: Gallium 0.4 on SVGA3D; build: RELEASE;
OpenGL version string: 2.1 Mesa 10.1.3
OpenGL shading language version string: 1.20

- VPN server running on a Debian server
OpenGL vendor string: VMware, Inc.
OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 0x209)
OpenGL version string: 1.4 (2.1 Mesa 8.0.5)

- A Mac on which the cardinal point assignment works (note Nvidia renderer)
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: NVIDIA GeForce 320M OpenGL Engine
OpenGL version string: 2.1 NVIDIA-8.16.74 310.40.00.10f02
OpenGL shading language version string: 1.20

Best,

Chris
--
Christopher Bailey, MSc
MEG Engineer, MINDLab Core Experimental Facility
Center of Functionally Integrative Neuroscience (CFIN)
Aarhus University, Denmark

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