[vtk-developers] QVTKRenderWindowInteractor bug in Mac OS

[take5v]

Hi David!

Thank you for the detailed response. I've changed Render call with
QVTKRenderWindowInteractor update method but I observed no performance
change. But I got lucky twice when changing window/level was real-time
without any lags. I have no idea how to reproduce this behavior again but I
do confirm the same inconsistency in Slicer3D on Windows machine. I found
changing window/level of 2d slices is slow but 3d volume rendering is fast.
There is a thread, apparently, with similar performance issue from Slicer3D:
https://discourse.slicer.org/t/2d-views-in-slicer-extremely-slow-on-windows/782.
I also tried vtkImageViewer2 without qt and got the same laggy behavior.

Nvidia driver: 411.31



David Gobbi wrote
> Hi Stas,
> 
> Here are a couple things to try to improve fps (no guarantees, though).
> 
> With QVTKRenderWindowInteractor, it is best to let Qt handle the
> render calls, rather than calling Render() directly.  So try replacing
> all of your calls to Render() with calls to self.update(), where 'self' is
> the QVTKRenderWindowInteractor.  If you do not do this, then it is
> possible that the Render() is hidden because it isn't associated with
> a Qt paint operation. By calling update() on a Qt widget, you ensure
> that Qt will call Render() synchronously with its paintEvent().
> 
> A second thing to try is to call Update() on your reader before using
> its output.  Most readers will 'stream' which means that they only
> read the slices that are requested by the VTK pipeline (possibly
> causing the reader to re-execute on future pipeline requests),
> unless you specifically call Update() which forces all the slices to be
> read into memory at once.  Since your example only has one input
> slice, I doubt that this is what is causing a slow-down for you, but it
> is still a good habit when working with VTK readers.
> 
>   - David
> 
> 
> On Wed, Oct 31, 2018 at 10:57 AM take5v <

> stas.truhan@

> > wrote:
> 
>> Another issue but within the same context of mine toy example (script of
>> which I posted above) is a slow fps during window/level change on
>> Windows.
>> This process is slow and laggy even during rendering the super small
>> image
>> of vtk.png from VTKData.
>>
>> CPU: GeForce GTX 680
>> GPU: Intel i7-3770K
>>
>>
>>
>> -----
>> Best regards,
>> Stanislau Trukhan
>> --
>> Sent from: http://vtk.1045678.n5.nabble.com/VTK-Dev-f1251487.html
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-----
Best regards,
Stanislau Trukhan
--
Sent from: http://vtk.1045678.n5.nabble.com/VTK-Dev-f1251487.html