[ITK-users] Creating 3D dome using ITK

[Richard Beare]

Yep - even better.

On Wed, May 10, 2017 at 9:19 PM, robert tamburo <robert.tamburo at gmail.com>
wrote:

> 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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>>
>>
>> _____________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Kitware offers ITK Training Courses, for more information visit:
>> http://www.kitware.com/products/protraining.php
>>
>> Please keep messages on-topic and check the ITK FAQ at:
>> http://www.itk.org/Wiki/ITK_FAQ
>>
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>>
>
>
> --
> robert
>
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