[vtkusers] vtkImageThresholdConnectivity

[David Gobbi]

Regarding the Update(), I think that I should add an option in the
SliceMapper to _always_ request the whole extent.  Usually people
don't want to stream the data through the pipeline on every render,
they want to update the whole volume just once.

 - David


On Fri, Sep 5, 2014 at 12:51 PM, Maarten Beek <beekmaarten at yahoo.com> wrote:
> Your patch seems to have solved my crash.
>
> Your Update() suggestion is indeed still a good one...
>
> Maarten
>
>
> On Friday, September 5, 2014 2:07:54 PM, David Gobbi <david.gobbi at gmail.com>
> wrote:
>
>
> The patch can be found at the following web page, if you are able to
> try it out then I'd like to hear whether it works for you.
>
> http://review.source.kitware.com/#/c/16916/1
>
> Even with this patch, it is still a good idea to call Update() on the
> filter before Render(), because otherwise the filter will re-execute
> every time the slice location changes, causing the render to be very
> slow.
>
> - David
>
> On Fri, Sep 5, 2014 at 12:06 PM, Maarten Beek <beekmaarten at yahoo.com> wrote:
>> Thanks - David.
>>
>> I'll try your Update() suggestion. I made my app is quite complex; not
>> sure
>> I can find the right stop for the function call... ;-)
>>
>> In the meantime, do you need anything from me to help you with the fix?
>>
>> Maarten
>>
>>
>> On Friday, September 5, 2014 1:29:45 PM, David Gobbi
>> <david.gobbi at gmail.com>
>> wrote:
>>
>>
>> Yes, it is a bug, and exactly at line 448 like you said.  Thanks.
>> I'll start working on a patch, since I submitted the original code.
>>
>> In the meantime, you might be able to work around the problem by
>> calling Update() on vtkImageThresholdConnectivity before calling
>> Render() on your RenderWindow.  That will cause the filter to produce
>> a 3D extent, and then vtkImageSlice will take just the slice it needs.
>>
>> - David
>>
>> On Fri, Sep 5, 2014 at 11:04 AM, David Gobbi <david.gobbi at gmail.com>
>> wrote:
>>> Hi Maarten,
>>>
>>> I think it might be a bug, so I will investigate.  This filter needs
>>> the whole extent from the input because it does a 3D connectivity
>>> operation, but that shouldn't impact the extent that it produces as
>>> output.  If asked for a single-slice output extent, then it should
>>> pull in a 3D input extent but produce a 2D output extent.
>>>
>>>  - David
>>>
>>> On Fri, Sep 5, 2014 at 10:40 AM, Maarten Beek via vtkusers
>>> <vtkusers at vtk.org> wrote:
>>>> Hi all,
>>>>
>>>> I have a problem with vtkImageThresholdConnectivity in a pipeline with
>>>> vtkImageSlice.
>>>>
>>>> The vtkImageSlice reduces the extent of the image to the slice that is
>>>> visible, and vtkImageThresholdConnectivity allocates its output
>>>> accordingly.
>>>> However it then takes the scalar pointer of the output for the extent of
>>>> the
>>>> (3d) input image.
>>>> This happens on line 448 of vtkImageThresholdConnectivity.cxx (VTK
>>>> 6.1.0).
>>>>
>>>> Is this a bug, or am I doing something wrong?
>>>>
>>>> Thanks - Maarten
>>
>>
>
>