| Three dimensional Polyfillv [message #58809] |
Mon, 18 February 2008 22:54  |
twhaw
Messages: 5
Registered: February 2008
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Junior Member |
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Good day.
I have been following this newsgroup for a while and it is really very
helpful in solving many problems that I have encountered in IDL
programming.
Currently I am writting an IDL procedure to sample some points on the
surface of a 3D blob (from a 3D volume).This is later used to contruct
3D point distribution model (PDM) of the blob. The PDM is actually a
(3, n) array of rectangular coordinates. I would like to reconstruct
the blob by using the PDM. To do this, I need the subscripts of the
array elements contained inside the PDM. This can be done by using
Polyfillv for in the case of 2D array. Is there any similar function
for 3D volume?
Your kind assistance in this matter is highly appreciated.
Thank you in advance.
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| Re: Three dimensional Polyfillv [message #58829 is a reply to message #58809] |
Sun, 24 February 2008 18:21  |
twhaw
Messages: 5
Registered: February 2008
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Junior Member |
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Dear Chris,
Thanks. I guess there is no similar function or routine for 3D.
Anyway, I am evaluating the possibility of using of IDLanROI and other
functions.
Many thanks again for your kind response.
Cheers.
On Feb 23, 8:11 pm, Spon <christoph.b...@gmail.com> wrote:
> On Feb 19, 6:54 am, twhaw <wooihaw....@gmail.com> wrote:
>
>
>
>> Good day.
>
>> I have been following this newsgroup for a while and it is really very
>> helpful in solving many problems that I have encountered in IDL
>> programming.
>
>> Currently I am writting an IDL procedure to sample some points on the
>> surface of a 3D blob (from a 3D volume).This is later used to contruct
>> 3D point distribution model (PDM) of the blob. The PDM is actually a
>> (3, n) array of rectangular coordinates. I would like to reconstruct
>> the blob by using the PDM. To do this, I need the subscripts of the
>> array elements contained inside the PDM. This can be done by using
>> Polyfillv for in the case of 2D array. Is there any similar function
>> for 3D volume?
>
>> Your kind assistance in this matter is highly appreciated.
>
>> Thank you in advance.
>
> I'm guessing by the silence that the answer is 'no'. But you could
> start with SHADE_VOLUME and code up your own function, I suppose.
>
> Chris
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| Re: Three dimensional Polyfillv [message #58962 is a reply to message #58878] |
Tue, 26 February 2008 17:58 |
twhaw
Messages: 5
Registered: February 2008
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Junior Member |
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Dear all,
Thanks for your kind replies.
The reason why I can't use the 2D polyfillv is that the points are not
sampled as 2D slices in the rectangular coordinate system. Instead, it
is instead sampled in the spherical coordinate system (every 5 deg
longitudinally) and converted back to rectangular coordinates using
CV_COORD. I am sampling the blobs in the spherical coordinate system
so that I can get the same number of sample points regardless of the
size of the blobs (some are slightly small, some are slightly bigger).
I have checked out IDLanROI. It seems that we can defined a 3D ROI by
loading a (3, n) array. Maybe I can throw in my (3, n) array of sample
points and check whether a point in the 3D space is inside the ROI. In
this way, I might be able to get the points in the volume. But then
again, this method might be quite slow.
Many thanks again for your advices.
Cheers.
On Feb 27, 3:35 am, Mike <Michael.Mill...@gmail.com> wrote:
> What if you took your (3,n) values and, for each slice in your data
> volume, find the subset of the n points that fall on (or near enough
> to be considered "on") that slice? Then you could use polyfillv on
> that slice. I haven't done this with quite the data you have, but
> that is the method that I use to create 3D ROIs out of multiple 2D
> ROIs.
>
> Mike
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