[ITK-users] Creating 3D dome using ITK

[robert tamburo]

https://itk.org/Wiki/ITK/Examples/SpatialObjects/EllipseSpatialObject

On Wed, May 10, 2017 at 7:01 AM, Richard Beare <richard.beare at gmail.com>
wrote:

> A simple, although not necessarily efficient, way of doing this is to
> create an image with a single voxel where you want the centre of the
> (hemi)sphere to be, then dilate using the binary dilate filter
> (alternatively compute a distance transform them threshold). These two
> methods will give you a sphere, and you can then blank the half you don't
> want.
>
> Depending on the interface to ITK you are using, you could probably
> achieve something similar by generating images containing physical
> coordinates an plug those into formula for a sphere.
>
> On Wed, May 10, 2017 at 8:40 PM, Matt McCormick <
> matt.mccormick at kitware.com> wrote:
>
>> Hi,
>>
>> Depending on the code, MY_RADIUS may need to be divided by two.
>>
>> To avoid difficulties like this, it is better to work in physical
>> space versus index space. For more information on how physical space
>> works in ITK, see the itk::Image overview in the ITK Software Guide:
>>
>>   https://itk.org/ITKSoftwareGuide/html/Book1/ITKSoftwareGuide
>> -Book1ch4.html#x38-450004.1
>>
>>
>> There is a filter that can be used to anti-alias the mask.  Here is an
>> example:
>>
>>   https://itk.org/ITKExamples/src/Filtering/AntiAlias/SmoothBi
>> naryImageBeforeSurfaceExtraction/Documentation.html
>>
>>
>> I hope this helps.
>>
>> Matt
>>
>> On Wed, May 10, 2017 at 6:19 AM, sidharta <sidharta.gupta93 at gmail.com>
>> wrote:
>> > Dear all,
>> >
>> > I am trying to make a 3D dome (ie; Half Sphere) and then generating a
>> binary
>> > image out of it. The aim is to use this binary image as a mask in
>> > maskFilter. I was able to generate a 2D circular mask, which was
>> straight
>> > forward. I used this in a maskFilter and masked the 3D image using
>> > slicebysliceFilter.
>> >
>> > I can think of two ways to do it:
>> > 1. Make several masks of decreasing circle radius which ultimately would
>> > represent a dome.
>> > 2. Make a mask image and assign the values at indices accordingly to
>> get a
>> > dome mask.
>> >
>> > The first step seems doable but to my understanding would be an
>> overkill.
>> > I am not able to do the second step. Following is the code I tried:
>> >
>> > float MY_RADIUS = maskRegion.GetSize()[0];
>> > MaskIteratorType iterator(maskImage, maskImage->GetLargestPossibleR
>> egion());
>> > while (!iterator.IsAtEnd())
>> >         {
>> >                 const InputImageType::IndexType & index =
>> iterator.GetIndex();
>> >                 std::cout << "Index is " << index;
>> >                 float value = (index[0] - centerPoint[0]) * (index[0] -
>> centerPoint[0])
>> >                         + (index[1] - centerPoint[1]) * (index[1] -
>> centerPoint[1]);
>> >                 std::cout << "Compare - LHS = " << value << " RHS = "
>> << MY_RADIUS *
>> > MY_RADIUS << std::endl;
>> >                 if ((index[0] - centerPoint[0]) * (index[0] -
>> centerPoint[0])
>> >                         + (index[1] - centerPoint[1]) * (index[1] -
>> centerPoint[1])
>> >                         <= MY_RADIUS * MY_RADIUS)
>> >                 {
>> >                         iterator.Set(1);
>> >                 }
>> >                 --MY_RADIUS;
>> >                 ++iterator;
>> >         }
>> >
>> > After adding the cout commands I saw that --MY_RADIUS is incorrect. I
>> > generated the required sphere using matlab, just to get the values I
>> should
>> > assign to the pixels.
>> >
>> > Additionally, I noticed there is a need for anti-aliasing to the mask.
>> > Kindly let me know how this can be done iteratively.
>> >
>> > Thank you!
>> >
>> >
>> >
>> > --
>> > View this message in context: http://itk-users.7.n7.nabble.c
>> om/Creating-3D-dome-using-ITK-tp38201.html
>> > Sent from the ITK - Users mailing list archive at Nabble.com.
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>>
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>
>
> _____________________________________
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>
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>
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> http://www.kitware.com/products/protraining.php
>
> Please keep messages on-topic and check the ITK FAQ at:
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-- 
robert
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