[vtkusers] Render function's in-deterministic performance

[sebastian ordas]

Hi Siddharth,

I'm affraid you will have to provide some code to get useful inputs.

best regards
sebastian

PS: you can start by getting the latest VTK version (5.9.0) from git

On 12/06/2011 11:05 AM, Siddharth Vikal wrote:
> Hi,
>
> Let me first describe the set-up. I'm using a quad core, linux box 
> with vtk 5.4. I'm using Qt for GUI, thus QVTKWidget. I'm trying to 
> visualize image frames (1280 x1280 pixels) being captured from a 
> camera device. The anticipated frame rate is 30 fps. I've 'capture 
> frame' functionality happening in a separate thread. A minimal vtk 
> pipeline is set up using vtkImageData, vtkImageMapper, vtkActor2D. 
> Each time a new frame arrives, update is callled on the vtk pipeline 
> and the main thread running Qt, is notified to perform render 
> operation using paint event of QVTKWidget. For synchronization, mutex 
> is used. This setup seems to work just fine except from the 
> performance predictability standpoint.I've put timers in place to 
> measure time taken for each step.
>
> The problem is, the paint call (or eventually 'render' call) is not 
> behaving deterministically. For some frames, render completes within 
> 6-10 milliseconds, but for others, inexplicably, it starts taking 
> 50-70 milliseconds!! Now with new frame arriving at every 33 
> milliseconds (30 fps), I start loosing frames. I've tried the setup 
> using vtkImageActor (therefore without vtkImageMapper, vtkActor2D) as 
> well, but with similar behavior.
>
> I don't understand why is render taking 60-70 milliseconds? The data 
> is ready to be rendered. The in-deterministic aspect is even more 
> worrying.
>
> Can someone please help? It'll be greatly appreciated.
>
> regards
> Siddharth
>
>
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