[vtkusers] vtkBooleanOperationPolyDataFilter

[Vincent RIVOLA]

Hi,

Do you apply vtkThreshold on cell values or point values?
This will make a difference and I guess the missing cells is related to that.
If you really want to get the complementary part you should apply TheresoldByLower and ThresholdByUpper  on cell data I think.

Regards,

Vincent

Le 2 mars 2018 à 19:39, Polly Pui <polly_sukting at hotmail.com<mailto:polly_sukting at hotmail.com>> a écrit :

Hi Cory,
Thanks for your reply.
I extracted the result in red image by using the vtkthreshold (ThresholdByLower=0.085).
I tried to invert the extraction by using ThresholdByUpper=0.015, but the result weren't what i wanted.
The red image with white holes (the removed areas are what i wanted). The blue area is extracted using the inverted value of threshold.
<above_below.jpg>
I cant really understand what do you mean by boolean operations cant work on this case.
Are we not able to obtain the areas using "difference" operation?

Best,
Polly
________________________________
From: Cory Quammen <cory.quammen at kitware.com<mailto:cory.quammen at kitware.com>>
Sent: Thursday, March 1, 2018 9:01 PM
To: Polly Pui
Cc: vtkusers at vtk.org<mailto:vtkusers at vtk.org>
Subject: Re: [vtkusers] vtkBooleanOperationPolyDataFilter



On Thu, Mar 1, 2018 at 1:01 AM, Polly Pui <polly_sukting at hotmail.com<mailto:polly_sukting at hotmail.com>> wrote:

Hi,
I would like to obtain the areas which are removed in 'Red Image'.
Couldn't you invert the threshold operation to produce those areas instead of the red surface?
Green image is original data and Red image is the thresholded data.
I applied "union operation" in order to get the areas. I used the code given in https://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/BooleanOperationPolyDataFilter

The boolean operation filter won't work in this case because it does not handle boolean operations on overlapping surfaces.

HTH,
Cory
But the areas that I wanted couldn't be shown completely in grey image. The polygons are not connected.
Any suggestion on how can I improve this?
<boolean.jpg>

Thanks.


Best,
Polly

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