Dear list,
Does anyone know where I might find a description of the decimation algorithm used in tksurfer? I am decimating a scalp surface in tksurfer with some success. I am using the tool because it produces a relatively homogenous subsampling. However, it produces exactly the same subsampling on a given scalp surface for any value that I enter for the "spacing" setting. I would like to be able to control the degree of subsampling.
I realize that I'm using the tool in a non-conventional way. It seems to me that the decimation algorithm is using surface curvature in some way, which is likely why I am not able to control the degree of decimation on a scalp surface. If anyone has any thoughts on this, or could point me to any documentation, I'd be really grateful.
Best regards,
Stefan Tomic
Hi Stefan,
the downsampling doesn't use curvature. It is supposed to sample every nth node, where n is the spacing you select. If it's not doing that, then it's a bug. Perhaps Matti or Thomas can comment?
cheers, Bruce
On Tue, 27 Jul 2004, Stefan Tomic wrote:
Dear list,
Does anyone know where I might find a description of the decimation algorithm used in tksurfer? I am decimating a scalp surface in tksurfer with some success. I am using the tool because it produces a relatively homogenous subsampling. However, it produces exactly the same subsampling on a given scalp surface for any value that I enter for the "spacing" setting. I would like to be able to control the degree of subsampling.
I realize that I'm using the tool in a non-conventional way. It seems to me that the decimation algorithm is using surface curvature in some way, which is likely why I am not able to control the degree of decimation on a scalp surface. If anyone has any thoughts on this, or could point me to any documentation, I'd be really grateful.
Best regards,
Stefan Tomic
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Thanks Bruce,
The decimation algorithm works fine on meshes generated in freesurfer so I doubt it's a bug. We are trying to decimate a scalp mesh generated in EMSE and imported into freesurfer. The original meshes I tried had about 32,000 vertices and I'm wondering if this is not a large enough number for adequately controlling the degree of spacing. I am now trying to generate a scalp tessellation with the freesurfer tools to see if the decimation algorithm produces better results.
Best Regards,
Stefan Tomic
On Jul 28, 2004, at 5:30 AM, Bruce Fischl wrote:
Hi Stefan,
the downsampling doesn't use curvature. It is supposed to sample every nth node, where n is the spacing you select. If it's not doing that, then it's a bug. Perhaps Matti or Thomas can comment?
cheers, Bruce
On Tue, 27 Jul 2004, Stefan Tomic wrote:
Dear list,
Does anyone know where I might find a description of the decimation algorithm used in tksurfer? I am decimating a scalp surface in tksurfer with some success. I am using the tool because it produces a relatively homogenous subsampling. However, it produces exactly the same subsampling on a given scalp surface for any value that I enter for the "spacing" setting. I would like to be able to control the degree of subsampling.
I realize that I'm using the tool in a non-conventional way. It seems to me that the decimation algorithm is using surface curvature in some way, which is likely why I am not able to control the degree of decimation on a scalp surface. If anyone has any thoughts on this, or could point me to any documentation, I'd be really grateful.
Best regards,
Stefan Tomic
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Hi Stefan,
you could also try the matlab 'reducepatch' command.
Best, Darren
Stefan Tomic wrote:
Thanks Bruce,
The decimation algorithm works fine on meshes generated in freesurfer so I doubt it's a bug. We are trying to decimate a scalp mesh generated in EMSE and imported into freesurfer. The original meshes I tried had about 32,000 vertices and I'm wondering if this is not a large enough number for adequately controlling the degree of spacing. I am now trying to generate a scalp tessellation with the freesurfer tools to see if the decimation algorithm produces better results.
Best Regards,
Stefan Tomic
On Jul 28, 2004, at 5:30 AM, Bruce Fischl wrote:
Hi Stefan,
the downsampling doesn't use curvature. It is supposed to sample every nth node, where n is the spacing you select. If it's not doing that, then it's a bug. Perhaps Matti or Thomas can comment?
cheers, Bruce
On Tue, 27 Jul 2004, Stefan Tomic wrote:
Dear list,
Does anyone know where I might find a description of the decimation algorithm used in tksurfer? I am decimating a scalp surface in tksurfer with some success. I am using the tool because it produces a relatively homogenous subsampling. However, it produces exactly the same subsampling on a given scalp surface for any value that I enter for the "spacing" setting. I would like to be able to control the degree of subsampling.
I realize that I'm using the tool in a non-conventional way. It seems to me that the decimation algorithm is using surface curvature in some way, which is likely why I am not able to control the degree of decimation on a scalp surface. If anyone has any thoughts on this, or could point me to any documentation, I'd be really grateful.
Best regards,
Stefan Tomic
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
freesurfer@nmr.mgh.harvard.edu
-
Bruce Fischl -
Darren Weber -
Stefan Tomic