[vtkusers] method to extract regions

[Imre Goretzki]

Hi David,

thank you. I'll take a look at your class.

Regards
Imre

Am 29.12.2015 um 13:07 schrieb David Gobbi:
> Hi Imre,
>
> I have a connectivity filter that works directly on images, it can 
> label connected regions according to size and it should be much faster 
> (probably 1000x) than doing voxel checks via polydata:
> https://github.com/dgobbi/AIRS/blob/master/ImageSegmentation/vtkImageConnectivityFilter.h
> I'll probably be contributing this filter to VTK sometime in the near 
> future.
>
>  - David
>
>
> On Tue, Dec 29, 2015 at 4:02 AM, Imre Goretzki 
> <goretzki.imre at gmail.com <mailto:goretzki.imre at gmail.com>> wrote:
>
>     Is there an easier way in ITK?
>
>     Thanks
>     Imre
>
>
>     Am 28.12.2015 um 23:38 schrieb Imre Goretzki:
>>     Hey guys,
>>
>>     I use the vtkPolyDataConnectivityFilter from polydata to extract
>>     several different and more or less unknown regions.
>>     My problem is that I want to extract regions from this filter,
>>     but if I do this, the update process for all regions takes up to
>>     10minutes:
>>
>>     filter->SetExtractionModeToAllRegions();
>>     filter->Update();
>>     ...
>>
>>     for (int i = 0; i < filter->GetNumberOfExtractedRegions(); i++)
>>     {
>>     extractFilter->InitializeSpecifiedRegionList();
>>         extractFilter->AddSpecifiedRegion(i);
>>         extractFilter->Modified();
>>         extractFilter->Update();
>>     extractRegionData->DeepCopy(extractFilter->GetOutput());
>>     }
>>     extractFilter->InitializeSpecifiedRegionList();
>>
>>     Background for this: I want to use the points of each region to
>>     check whether they lie within an object in my binary
>>     mask image. So the pipeline would be like this:
>>
>>     1) Get all Regions
>>         2) get region /i/
>>              3) get points of region /i/
>>                  4) check if point /j/ lies within the binary mask
>>     /B/     (/B/_/j/ == 255)
>>                      4a) if true then add region to the extractFilter
>>     and break (-> next region /i/)
>>                      4b) if false then continue with next point /j/
>>     5) Mark all regions red (done easily)
>>     6) Mark some regions green that are above a specific size (can be
>>     accessed with filter->GetRegionSizes() )
>>     7) Mark some regions yellow (the regions that are extracted
>>     during step 1-4a)
>>
>>     I do not know if the PolyDataConnectivityFilter is the right
>>     class for this, I think it is.
>>     If I store the extractRegionData in a vector, all regions have
>>     the same number of points (which is kind of strange) but
>>     different number of cells (region size == number of cells is
>>     correct).
>>
>>     I would now try to get the points from the cells and check the
>>     binary mask, because the
>>
>>     vtkPolyData->GetNumberOfPoints()
>>
>>     and
>>
>>     vtkPolyData->GetPoint(pointCounter, point);
>>
>>     are not working correctly in this scenario (all regions are
>>     extracted because every single region has every point?
>>     i did not verify my guess but I think there would be the problem)
>>
>>     The binary mask is a vtkImageData, that could be transformed to
>>     vtkPolyData.
>>     The input image (already filtered with vtkMarchingCubes) and the
>>     binary mask have the same dimensions (x,y,z).
>>
>>     I hope you can imagine what I'm trying to do and have some tips
>>     for me, if my approach is correct.
>>
>>     Regards
>>     Imre
>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20151229/e14caacb/attachment.html>