[Sidefx-houdini-list] analysing symmetry

Andrew D Lyons tstexture at gmail.com
Thu Jul 8 14:28:03 EDT 2010


Hmm,

You might also compare the higher order derivatives of the surfaces -
ie. compare the curvature at each point etc. Also:

http://books.google.com/books?id=sbMdjy_93sYC&pg=PA222&lpg=PA222&dq=asymmetrical+volume+calculus&source=bl&ots=WkVuZdyKCD&sig=sdZTxxn29YYo7_G5U4i6GgSNbbQ&hl=en&ei=NRg2TIzKJtfjnQfZo733Aw&sa=X&oi=book_result&ct=result&resnum=5&ved=0CCgQ6AEwBA#v=onepage&q&f=false

Beyond that - it sounds like you might need to talk to a statistician.

Cheers


On 8 July 2010 10:12, jason lam <earthShatteringKaboom at gmail.com> wrote:
> interested in shape symmetry
> so we have volume data, and i have data which maps out anatomica landmarks
> eg AC joint to nipple both right and left
> so ideally i'd like a measure of how similar the surfaces are to each other
> currently what i get as data from my software is an error distance from
> -20mm to +20mm and a surface area in mm^2 at that error level
> I can also get just the raw data
>
> so my thought would be that if the surfaces are very similar in shape, but
> different in size, then the distances might be around 10mm iwth very little
> variance
> however if the breasts are smilar in volume but one is wobbly in shape, then
> the distances would vary a great deal
> hence i thought a standard distribution or a 'confidence interval' style
> statistic would be good
>
> ie the mean distance was 10mm with a 95% CI of -1 to +22
> would suggest very assymetrical breasts
>
>
>
> On Fri, Jul 9, 2010 at 2:32 AM, Andrew D Lyons <tstexture at gmail.com> wrote:
>
>> What are they most interested in for their single statistic?
>> Difference in volume? Offset in a specific plane?
>>
>> On 8 July 2010 09:56, jason lam <earthShatteringKaboom at gmail.com> wrote:
>> > a single statistic would be great
>> > we have the ability to do a colour map of the differences
>> > i was playing around with simply doing a standard distribution figuring
>> that
>> > the smaller it is, the more similar the surface, but a statistician i had
>> a
>> > chat to said that it wasn't correct
>> > He suggested logistic regression analysis, but I'm obviously not
>> > particularly strong on statistics...
>> >
>> > Jason
>> >
>> > On Fri, Jul 9, 2010 at 2:18 AM, Andrew D Lyons <tstexture at gmail.com>
>> wrote:
>> >
>> >> What's output data are you being asked to provide? One single
>> >> divergence statistic? A visualization? A set of key divergences?
>> >>
>> >> On 8 July 2010 09:42, jason lam <lam0127 at flinders.edu.au> wrote:
>> >> > Hi all,
>> >> >
>> >> > bit random, i've been a bit of a lurker for many years, having moved
>> into
>> >> > medicine now, but I'm doing some research into breast symmetry post
>> >> > reconstruction using 3d laser scanning and could do with a bit of help
>> >> >
>> >> > Essentially i mirror the breast and align to skeletal landmarks and
>> then
>> >> > find the distance between the 2 surfaces
>> >> > I need some help with the descriptive statistics to be able to
>> describe,
>> >> in
>> >> > a simple numerical way, the similarity of the surfaces and thus the
>> >> > symmetry.
>> >> > Was wondering if somewhere out there, there was someone who could
>> >> possibly
>> >> > help?
>> >> >
>> >> > Best regards
>> >> >
>> >> > Jason
>> >> > _______________________________________________
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>> >>
>> >>
>> >>
>> >> --
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>>
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>> Andrew D Lyons | Digital Artist | http://www.tstex.com
>> =======================================
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