<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">Hi Michael, <br>
<br>
Thanks for your feedback. <br>
<br>
1) SamplingSchemeQSpaceIMOCEstimation implemented IMOC method
proposed in the paper <br>
<a class="moz-txt-link-freetext" href="https://hal.archives-ouvertes.fr/hal-01154774/file/sampling_MICCAI2015.pdf">https://hal.archives-ouvertes.fr/hal-01154774/file/sampling_MICCAI2015.pdf</a><br>
It is a greedy method which can provide an initialization for
optimization method (CNLO) to get a further improved scheme. <br>
I will release CNLO later when I have time. At this moment, you
can just use IMOC for your task. <br>
<br>
You cannot use tessellation order more than 7 directly for
SamplingSchemeQSpaceIMOCEstimation, because it uses the stored
gradient tables in ~/.dmritool/Data/Tessellation. You did not see
the warning message because you build the code with
VERBOSITY_LEVEL=0. I just modified the code and pushed it to
github so that you can see the warning message. <br>
If you want to try tessellation order more than 7, you can use: <br>
SphereTessellator --tessorder 8 --hemisphere grad_t8.txt<br>
SamplingSchemeQSpaceIMOCEstimation grad.txt --numberOfSamples
60,90 --fineOrientations grad_t8.txt<br>
In my laptop, it takes 18 seconds. <br>
Tessellation order of 7 is much faster, and practically enough for
your usage. <br>
<br>
2) For the shell with 60 samples, there is a minimal angle for
each sample. Then we have 60 minimal angles. <span
style="font-family:monospace,monospace">OrientationStatistics
shows (min, max, mean, std)</span> for these 60 minimal angles,
also for shell with 90 samples and the combined shell with 150
samples. <br>
<br>
best,<br>
Jian Cheng<br>
<br>
On 05/17/2016 01:24 PM, Michael Dayan wrote:<br>
</div>
<blockquote
cite="mid:CAK8FaMPtRWFRhjcNACWm3Js6fQuwskvkUGhRxFop44ZJbRZHeQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>
<div>dmritool has been very useful to generate multi-shell
scheme but I would like to know more about the optimal
protocol to generate such shemes:<br>
<br>
</div>
1) Is SamplingSchemeQSpaceIMOCEstimation the most adequate
function for this purpose? What parameters to change to
improve the results? I tried to use higher "tesselate orders"
than 7 (e.g. 8, 11, ...) but kept getting a "Segmentation
fault (core dumped)" error.<br>
<br>
</div>
2) To assess the quality of the results how to interpret the
statistics of the generated scheme, in particular the minimum
and maximum angle values? Below is an example of statistics for
a 2-shell scheme with 60 and 90 directions in the first and
second shell.<br>
<br>
<span style="font-family:monospace,monospace"> OrientationStatistics
imoc_60x90_shell1.txt imoc_60x90_shell2.txt --combine<br>
file: imoc_60x90_shell1.txt<br>
size = 60<br>
60 unique samples, 0 antipodal samples, 0 repeated samples.<br>
minimal angle = 14.1538, radian=0.24703 (covering radius)<br>
maximal angle = 14.7301, radian=0.257089<br>
mean angle = 14.3346<br>
std angle = 0.144217<br>
upper bound (120 points) = 19.9391, radian=0.348003<br>
upper bound (60 points) = 28.2194, radian=0.492521<br>
electrostaticEnergy (order=2) = 3.05481<br>
electrostaticEnergy (order=1) = 1.98694<br>
<br>
file: imoc_60x90_shell2.txt<br>
size = 90<br>
90 unique samples, 0 antipodal samples, 0 repeated samples.<br>
minimal angle = 11.5536, radian=0.201648 (covering radius)<br>
maximal angle = 19.6656, radian=0.34323<br>
mean angle = 12.3677<br>
std angle = 1.45567<br>
upper bound (180 points) = 16.2761, radian=0.284071<br>
upper bound (90 points) = 23.0295, radian=0.401941<br>
electrostaticEnergy (order=2) = 2.8735<br>
electrostaticEnergy (order=1) = 1.92306<br>
<br>
Combine 2 orientations<br>
size = 150<br>
150 unique samples, 0 antipodal samples, 0 repeated samples.<br>
minimal angle = 8.95306, radian=0.15626 (covering radius)<br>
maximal angle = 14.4468, radian=0.252144<br>
mean angle = 10.2967<br>
std angle = 1.42696<br>
upper bound (300 points) = 12.6048, radian=0.219995<br>
upper bound (150 points) = 17.8313, radian=0.311216<br>
electrostaticEnergy (order=2) = 2.79829<br>
electrostaticEnergy (order=1) = 1.89174<br>
Spherical code cost function = 0.1903</span><br>
<br>
<br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
dmritool-discussion mailing list
<a class="moz-txt-link-abbreviated" href="mailto:dmritool-discussion@www.nitrc.org">dmritool-discussion@www.nitrc.org</a>
<a class="moz-txt-link-freetext" href="http://www.nitrc.org/mailman/listinfo/dmritool-discussion">http://www.nitrc.org/mailman/listinfo/dmritool-discussion</a>
</pre>
</blockquote>
<br>
</body>
</html>