[Insight-users] Creating a spatial object from a binary image

[Luis Ibanez]

Hi Vincent,

We discussed this issue today in the weekly developers
meeting and agreed in creating a new SpatialObject
class called

           ImageMaskSpatialObject

With a modified version of the IsInside() method.
This new class will actually check for the values to
be on in the binary image mask.

I'll send you an early version of this class by the
end of the day so you can give it a try.



    Regards,



       Luis


-------------------
Vincent Chu wrote:

> Hi Luis,
> 
> The quick and dirty fix doesn't seem to work.  The ValueAt function seems
> to call IsInside indirectly, resulting an infinite recursion.  Any
> suggestion around this?
> 
> Thanks,
> 
> Vincent
> 
> On Thu, 3 Jun 2004, Luis Ibanez wrote:
> 
> 
>>Hi Vincent,
>>
>>Thanks for pointing this out.
>>
>>This looks like a bug in the ImageSpatialObject.
>>
>>We just entered as Bug # 909
>>http://www.itk.org/Bug/bug.php?op=show&bugid=909&pos=0
>>
>>
>>The "IsInside()" method is simply checking if
>>the point is inside the bounding box of the image.
>>
>>As a quick and dirty fix please do the following:
>>
>>1) Go to
>>
>>    Insight/Code/SpatialObjects/
>>                 itkImageSpatialObject.txx
>>
>>
>>2) Search for lines 68 to 78 where the methods
>>    "IsInside()" is defined.
>>
>>3) Replace the current content of "IsInside()" with
>>    a delegation like
>>
>>      {
>>      this->ValueAt( point, value, depth, name );
>>      return (value != 0);
>>      }
>>
>>
>>For a long term solution we probably need to
>>add a explicit class:
>>
>>        ImageMaskSpatialObject
>>
>>
>>with an IsInside() methods as the one you just
>>implemented.
>>
>>
>>
>>Please let us know if you find any other problems,
>>
>>
>>    Thanks
>>
>>
>>      Luis
>>
>>
>>-------------------
>>Vincent Chu wrote:
>>
>>>Hi Luis,
>>>
>>>Thanks for the reply.  I tried SetImage() to an image whose pixel type is
>>>unsigned char, and each pixel has value either 0 or 255.  However,
>>>isInside(PointType x) seems to return true regardless of whether x is a
>>>point where the pixel value is 0 or 255.  This is what I have in code:
>>>
>>>/////////////////////////////////////////////////////////////////////
>>>
>>>typedef itk::Point<double,3> Point;
>>>  Point insidePoint;
>>>  insidePoint[0]=182;
>>>  insidePoint[1]=256;
>>>  insidePoint[2]=15;
>>>  if( imageSO->IsInside(insidePoint) )
>>>	  std::cout << insidePoint << " is inside the image." <<
>>>std::endl;
>>>  double returnedValue;
>>>  imageSO->ValueAt(insidePoint,returnedValue);
>>>  std::cout << "ValueAt(" << insidePoint << ") = " << returnedValue <<
>>>std::endl;
>>>  insidePoint.Fill(1);
>>>  if( imageSO->IsInside(insidePoint) )
>>>	  std::cout << insidePoint << " is inside the image." <<
>>>std::endl;
>>>  imageSO->ValueAt(insidePoint,returnedValue);
>>>  std::cout << "ValueAt(" << insidePoint << ") = " << returnedValue <<
>>>std::endl;imageSO->ValueAt(insidePoint,returnedValue);
>>>
>>>//////////////////////////////////////////////////////////////////////////
>>>
>>>And I get the following output:
>>>
>>>182  256  15 is inside the image.
>>>ValueAt(182  256  15) = 255
>>>1  1  1 is inside the image.
>>>ValueAt(1  1  1) = 0
>>>
>>>Did I setup something wrong?
>>>
>>>Thanks,
>>>
>>>Vincent
>>>
>>>
>>>
>>>
>>>On Thu, 3 Jun 2004, Luis Ibanez wrote:
>>>
>>>
>>>
>>>
>>>>Hi Vincent,
>>>>
>>>>You are in the right track,
>>>>the class to use is the:
>>>>ImageSpatialObject.
>>>>http://www.itk.org/Insight/Doxygen/html/classitk_1_1ImageSpatialObject.html
>>>>
>>>>
>>>>Just connect your image mask to the ImageSpatialObject
>>>>using its "SetImage()" method.
>>>>
>>>>There is no overload for doing this. At the end,
>>>>the spatial object just need to answers the queries
>>>>for whether a pixel is "inside" of the object (your
>>>>image mask in this case) or not. What the Spatial
>>>>object is doing is simply delegating the quiery to
>>>>the underlying image mask that you provided.
>>>>
>>>>
>>>>Please let us know if you have further questions,
>>>>
>>>>
>>>>   Thanks
>>>>
>>>>
>>>>     Luis
>>>>
>>>>
>>>>----------------
>>>>Vincent Chu wrote:
>>>>
>>>>
>>>>
>>>>>Hi,
>>>>>
>>>>>I am new to ITK and would like to perform registration between two images.
>>>>>The region of interest has arbitrary shapes, and I previously read from
>>>>>the list that we can use SetMovingImageMak() and SetFixedImageMask() in
>>>>>ImageToImageMetrics to set the region in which the metrics will be
>>>>>computed.  However, those two methods expect spatial objects as parameter,
>>>>>and I have trouble converting a binary image into a spatial object.  I
>>>>>have tried ImageSpatialObject, but the entire binary image would be
>>>>>created as one big spatial object.  Which class should I use instead?
>>>>>
>>>>>Thanks,
>>>>>
>>>>>Vincent
>>>>>_______________________________________________
>>>>>Insight-users mailing list
>>>>>Insight-users at itk.org
>>>>>http://www.itk.org/mailman/listinfo/insight-users
>>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>
>>
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