[vtkusers] Newbie question about VTK speed

[Francois Bertel]

I don't know but I see that you're doing computation in your loop. Try
to time this overhead first by commenting out viewer->Render().

On 1/4/08, Hughes, Mike <msh at cmrl.wustl.edu> wrote:
> Thanks for the really fast answer.
>
> I checked my NVIDIA openGL settings and it seems that the vertical blank
> option was not set (correct me if I'm wrong, I've attached a screen shot of
> the dialog box I'm refering to).
>
> I'd be glad to check any other suggestions you might have.
>
> Regards,
>
> Mike
>
> PS
> Do you have any idea of what sort of frame rates should I expect?
>
> -----Original Message-----
> From: Francois Bertel [mailto:francois.bertel at kitware.com]
> Sent: Friday, January 04, 2008 9:18 PM
> To: Hughes, Mike
> Subject: Re: [vtkusers] Newbie question about VTK speed
>
> Hi Mike,
>
> 180/2.57=70. It seems you have vertical blank sync option on with a monitor
> working at 70Hz. If you want to benchmark the framerate, you have to set it
> off. Run nvidia-settings,  Uncheck "Sync to VBlank"  in OpenGL Settings. or
> in your shell , set the following environment variable to 0 (see any nvidia
> documentation):
> $export __GL_SYNC_TO_VBLANK=0
>
>
> On 1/4/08, Hughes, Mike <msh at cmrl.wustl.edu> wrote:
> > I've just started using VTK to do image processing.  I wrote the
> > program below (Vol-r5) to test the frame rate for writing different
> > images to the screen of my computer (Dual dual-core Xeons with and
> > VCQFX1500-PCIE-PB Nvidia 1500 video adapter running Ubuntu linux with
> > working OpenGL drivers installed).
> >
> > When I run the program I get the following output:
> >         $ ./Vol-r5
> >         dt= 2.57 for: 180 frames
> > Where dt is the execution time to compute and display 180 frames.
> >
> > This seems to be astoundingly slow for a machine with working OpenGL
> > drivers installed.  I've explored the VTK class hierarchy and it seems
> > that if OpenGL is available it should be automatically used.  I hope
> > that I'm mistaken on this.
> >
> > Is there a way to display frames at a higher rate?  I would ultmately
> > like to display 512x512 images (which takes about 9 sec with the program
> below).
> >
> > Vol-r5.cpp listing....
> >
> > #include "vtkImageWriter.h"
> > #include "vtkImageReader.h"
> > #include "vtkPointData.h"
> > #include "vtkRenderer.h"
> >
> > //#include "vtkRenderWindow.h"
> > //#include <vtkXOpenGLRenderWindow.h>
> >
> > #include "vtkImageViewer.h"
> > #include "vtkRenderWindowInteractor.h"
> > #include "vtkStructuredPoints.h"
> > #include "vtkFloatArray.h"
> > #include "vtkContourFilter.h"
> > #include "vtkPolyDataMapper.h"
> > #include "vtkActor.h"
> > #include "vtkImageCast.h"
> >
> > #include <time.h>
> >
> > const float Pi=3.14159;
> > const int NumberOfFrames=180;
> >
> > int main ()
> > {
> >
> >         float sp, z, y, x, s, dx,dy,scale;
> >         int i, j, k, ii, kOffset, jOffset, offset,h;
> >         int xSize=255;
> >         int ySize=255;
> >         int zSize=0;
> >         clock_t start, stop;
> >         dx=1.0/((double)xSize);
> >         dy=1.0/((double)ySize);
> >
> >         vtkImageData *image = vtkImageData::New();
> >         image->SetDimensions(xSize+1,ySize+1,zSize+1);
> >         image->SetScalarTypeToFloat();
> >         image->AllocateScalars();
> >
> >         float *ptr = static_cast<float*>(image->GetScalarPointer());
> >         float *startptr;
> >         startptr = ptr;
> >
> >         vtkImageViewer *viewer = vtkImageViewer::New();
> >         viewer->SetInput(image);
> >         viewer->SetColorWindow(20.0);
> >         viewer->SetColorLevel(0.0);
> >         start=clock();
> >         for(scale=1.0,k=0;k<NumberOfFrames;k++,scale+=0.1)
> >         {
> >                 ptr=startptr;
> >                 for(x=0.0,i=0;i<xSize+1;i++,x+=dx)
> >                         for(y=0.0,j=0;j<ySize+1;j++,y+=dy)
> >                                 *ptr++ = scale*sin(8.0*Pi*x)*sin(8.0*Pi*y);
> >                 viewer->Render();
> >         }
> >         stop=clock();
> >         cout << " dt= " <<
> > ((double)(stop-start))/((double)CLOCKS_PER_SEC) << " for: " <<
> > NumberOfFrames << " frames" << endl;
> >
> >         viewer->Delete();
> >         image->Delete();
> >         // Clean up
> >         return 1;
> > }
> >
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>
>
> --
> François Bertel, PhD  | Kitware Inc. Suite 204
> 1 (518) 371 3971 x113 | 28 Corporate Drive
>                       | Clifton Park NY 12065, USA
>
>


-- 
François Bertel, PhD  | Kitware Inc. Suite 204
1 (518) 371 3971 x113 | 28 Corporate Drive
                      | Clifton Park NY 12065, USA