[Mrtrix-discussion] disp_profile reports "unexpected number of SH coefficients"

[Robert Smith]

Bryce

Normally I'd leave this one to Donald, but he's off sipping wine somewhere.

This appears to be a small glitch that managed to sneak its way into
version 0.2.10. It will not cause any problems other than the unnecessary
error message.

If you want to get rid of the message, you can make the following change to
the source code.
In the file cmd/disp_profile.cpp, line 130 reads:

if (values.columns() != guint (DWI::SH::NforL (lmax))) {

change it to:

if (!is_response && values.columns() != guint (DWI::SH::NforL (lmax))) {


In case you're curious as to what's going on:
The disp_profile command can display the profiles of both spherical
harmonic (e.g. diffusion signal profiles, Fibre Orientation
Distributions) and rotational harmonics (e.g. single-fibre response
function). The -response option you provided is supposed to tell the
program that the text file you are feeding it contains the latter
rather than the former. In the 0.2.10 code, the program erroneously
ignores this information, but subsequently figures it out itself
(based on the number of coefficients in the text file); hence the
erroneous error message telling you what you already know.

Best regards
Rob



--

Robert Smith
PhD Candidate

The Florey Institute of Neuroscience and Mental Health
Melbourne Brain Centre - Austin Campus
245 Burgundy Street
Heidelberg Vic 3084
Ph: +61 3 9035 7128
Fax: +61 3 9035 7301
www.florey.edu.au



On Sat, Dec 1, 2012 at 9:43 AM, Bryce Wilkins <brycewil at usc.edu> wrote:

>  Dear mrTrix community,
>
> I am currently running mrTrix 0.2.10 (mrtrix-0.2.10_2012-02-10) on Linux
> and repeatedly encounter the error message:
>
> *disp_profile: unexpected number of SH coefficients - assuming response
> function*
>
> when I run the following command to plot the estimated single fiber
> response function:
>
> *disp_profile -response sf_response.txt*
>
> I have followed the documentation, specifically "Data pre-processing"
> section, where it describes how to generate a single-fiber mask, and call
> *estimate_response* to determine the SH coefficients for the single
> fiber.  I edited a custom single-fiber mask, based on FA levels, and
> ensured that all voxels in the mask were in white matter regions, and not
> be voxels of erroneous FA values (e.g. FA > 1).
>
> Examples from two of my *sf_response.txt* files are:
>
> 1862.36 -570.495 84.5122 -8.29821 0.629007
>
> 1296.21 -909.403 383.255 -116.241 28.1946
>
> These values seem consistent with what is described in the documentation.
> So, I find it very odd that I am receiving the above error message.
> Furthermore, even though the error appears, the actual SH profile displayed
> changes (i.e. it doesn't seem to assume and then load a default response
> function as the error states).
>
> Can anyone explain what is causing the *disp_profile* error above?  May
> be the outputting of the error message is the error itself?  Can anyone
> check *disp_profile -response* using the values I have listed above.
> What are your outcomes?
>
> Thank-you researchers!
> Bryce
>
>
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>
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