[vtkusers] vtkImageReslice speed

[alex. gouaillard]

On Sun, 2006-03-26 at 02:15, David Gobbi wrote:
> Hi Lyubomir,
> 
> There is nothing special about the number "256" in vtkImageReslice,
> so the loss of performance is probably due to a secondary issue.
> 
> For example, if you are using vtkImageActor or vtkImagePlaneWidget
> to display the image, note that the size of the OpenGL texture is
> always
> a power of two, so an image that is 257 pixels on a side will be
> displayed
> on a texture that is 512 pixels on a side.

well, OpenGl has been handling non power of two textures for several
years already (see
http://oss.sgi.com/projects/ogl-sample/registry/ARB/texture_non_power_of_two.txt). Depending on your implementation of OpenGl that is more or less supported, but I assume Mesa would. Is there any reason why this happen in VTK (i.e. is it hard-coded?).

alex

> 
>  - David
> 
> 
> ----- Original Message ----
> From: Lyubomir Zagorchev <lzagorch at verizon.net>
> To: vtkusers at vtk.org
> Sent: Saturday, March 25, 2006 11:45:15 AM
> Subject: [vtkusers] vtkImageReslice speed
> 
> I am using vtkImageReslice to cut three orthogonal cross sections from
> a volume.
> I noticed that if the volume has axial dimensions greater than 256 the
> performance 
> of the filter becomes very slow ( even if the axial dimensions are
> 257, the speed
> decreases significantly). Could someone briefly explain what is the
> reason for 
> that? Can I do something in my code that will increase the speed of
> the filter?
>  
> Thank you,
>  
> Lyubomir 
>