[vtkusers] canny edge detection help

[Ramamurthy, Rajesh (GE Global Research, US)]

This worked and I have been using the canny edge detection code. Today I noticed a crash in the algorithim coming from 

vtkSubPixelPositionEdgels::Move

where there is a divide by zero at

      c = -0.5*b/a;

I noticed that when I increase the Gradient and threshold values for the algorithm, the crash goes away - so it appears that some remote pixels are being picked up as edges.

Not sure what to do here - I would hope that there is at least a way to fail gracefully , but there are no exception handing in there.

Any ideas? - cant share the image unfortunately.

Regards
Rajesh
-----Original Message-----
From: Bill Lorensen [mailto:bill.lorensen at gmail.com] 
Sent: Thursday, August 24, 2017 1:45 PM
To: Ramamurthy, Rajesh (GE Global Research, US)
Cc: vtkusers at vtk.org
Subject: EXT: Re: [vtkusers] canny edge detection help

Remove the

vtkImageLuminance from the pipeline.


On Thu, Aug 24, 2017 at 12:17 PM, Ramamurthy, Rajesh (GE Global Research, US) <ramamurr at research.ge.com> wrote:
> Hi All,
>
>
>
> I am new to using VTK and hence I am trying to work with the toolkit 
> using the online examples for canny edge detection and reading DICOM images.
>
>
>
> My need is to do sub-pixel canny edge detection of a DICOM image and 
> then write out the results to a file. I found examples for both and 
> combined it together into a test app code as below.
>
>
>
> The code builds, and runs but I am always getting no edges written to 
> my output edges.txt file. I tried playing with different canny 
> parameters but it did not seem to change the situation. I want the 
> edges of the attached DCM file to be found, I have a sample edge 
> detection shown in the attached text file here.
>
>
>
> Thanks!
>
> Rajesh
>
>
>
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at 
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Search the list archives at: http://markmail.org/search/?q=vtkusers
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/vtkusers
>



--
Unpaid intern in BillsBasement at noware dot com