OpenMEEG Error #1

Hey Brainstorm forum!

I am having problems generating a BEM head model for all of my subjects’ in Brainstorm. However, computing single and multiple sphere models work just fine.

I have tried numerous ways of loading the MRI anatomy into Brainstorm to see if manipulating those variables would allow me to make a BEM model without receiving an error; but nothing has worked. Any help is much appreciated! Thanks in advance.

Whenever I attempt to create a BEM model, I get this error message:

** Error: OpenMEEG error #1:
** om_assemble version 2.1.dev (718) compiled at Apr 21 2011 18:22:16
**
** | ------ om_assemble
** | -HM
** | C:\Documents and Settings\sklimaj.brainstorm mp\openmeeg.geom
** | C:\Documents and Settings\sklimaj.brainstorm mp\openmeeg.cond
** | C:\Documents and Settings\sklimaj.brainstorm mp\openmeeg_hm.bin
** | -----------------------
** Sorted List : 1 0 2
** Sorted Domains : Brain Skull Scalp Air
** Total number of points : 30378
** Total number of triangles : 60911
** Checking
** Mesh 0 : internal conductivity = 1 and external conductivity = 0.0125
** Mesh 1 : internal conductivity = 0.0125 and external conductivity = 1
** Mesh 2 : internal conductivity = 1 and external conductivity = 0
** triangles 2411 and 4705 are intersecting
** triangles 2411 and 19236 are intersecting
** triangles 2826 and 4725 are intersecting
** triangles 2826 and 4726 are intersecting
** triangles 2827 and 4726 are intersecting
** triangles 2827 and 19306 are intersecting
** triangles 2827 and 19307 are intersecting
** triangles 2830 and 19304 are intersecting
** triangles 2831 and 19304 are intersecting
** triangles 3421 and 10139 are intersecting
** triangles 3421 and 10140 are intersecting
** triangles 3422 and 15392 are intersecting
** triangles 4362 and 8205 are intersecting
** triangles 4363 and 8205 are intersecting
** triangles 4364 and 8205 are intersecting
** triangles 4364 and 8206 are intersecting
** triangles 4369 and 15378 are intersecting
** triangles 4369 and 15379 are intersecting
** triangles 4369 and 15382 are intersecting
** triangles 4370 and 15382 are intersecting
** triangles 4705 and 19240 are intersecting
** triangles 4705 and 19243 are intersecting
** triangles 4725 and 13599 are intersecting
** triangles 4725 and 13600 are intersecting
** triangles 8206 and 18213 are intersecting
** triangles 8567 and 13614 are intersecting
** triangles 10139 and 15384 are intersecting
** triangles 10140 and 15392 are intersecting
** triangles 10141 and 15392 are intersecting
** triangles 11449 and 13614 are intersecting
** triangles 11449 and 13615 are intersecting
** triangles 11450 and 13614 are intersecting
** triangles 12354 and 19210 are intersecting
** triangles 12354 and 19236 are intersecting
** triangles 12354 and 19237 are intersecting
** triangles 13600 and 19293 are intersecting
** triangles 13600 and 19296 are intersecting
** triangles 13610 and 19306 are intersecting
** triangles 13611 and 19304 are intersecting
** triangles 13611 and 19305 are intersecting
** triangles 13611 and 19306 are intersecting
** triangles 13614 and 19304 are intersecting
** triangles 15377 and 18226 are intersecting
** triangles 15378 and 18226 are intersecting
** triangles 15378 and 18227 are intersecting
** triangles 15378 and 18228 are intersecting
** triangles 15382 and 18230 are intersecting
** triangles 15382 and 18231 are intersecting
** triangles 15383 and 18230 are intersecting
** triangles 15384 and 18230 are intersecting
** triangles 18212 and 18223 are intersecting
** triangles 18212 and 18226 are intersecting
** triangles 18213 and 18223 are intersecting
** !!!
** !!! WARNING !!!
** !!!
** Mesh is self intersecting !
** Mesh Info :
** # points : 10242
** # triangles : 20480
** Euler characteristic : 2
** Min Area : 4.70203e-008
** Max Area : 1.13966e-005
** Self intersection for mesh number 0
** !!!
** !!! WARNING !!!
** !!!
** 2 meshes are intersecting !
** Mesh Info :
** # points : 10242
** # triangles : 20480
** Euler characteristic : 2
** Min Area : 4.70203e-008
** Max Area : 1.13966e-005
** Mesh Info :
** # points : 10242
** # triangles : 20480
** Euler characteristic : 2
** Min Area : 1.04696e-006
** Max Area : 1.29389e-005
** Mesh::contains_point§ Error. Are you sure the mesh is closed?
** 12.5752

Hi,

how did you generate your BEM surfaces? OpenMEEG is basically complaining because at least one of your meshes is not a closed surface which moreover contains self-intersecting triangles. With such a mesh OpenMEEG cannot guarantee accurate solutions.

Cheers,
Alex

Hi Alex -

Thank you so much for your response! At least I know why I am getting the error now.

Our surfaces are generated through FreeSurfer in an autoanalysis pipeline.

I have been trying to figure out how to close the surfaces that are generated through FreeSurfer, but without any success so far. Is there anything within Brainstorm that would allow for preprocessing of the BEM surface to ensure it is ready to be ran through OpenMEEG?

Best,

Stefan

what tool do you use to generate the surfaces? I am only aware of the the MNE tools to do this (mne_watershed_bem and mne_flash_bem).

Alex