[vtkusers] Performance issues with triangle strips

[marcin.krotkiewski]

Hello,

I am testing efficiency of triangle strips in visualization of large 
digital elevation models. Initial tests show signifficant improvements 
in memory usage, but also some performance issues: it seems that for 
example the vtkContourFilter performs _much_ worse when using strips.

I am running VTK7 with OpenGL2 backend on Ubuntu. For an example model 
with 46e6 triangles, I tested two versions of the code (I use Java 
wrappings):

                 grid = vtkPolyData();
                 grid.SetPoints(nodes);
                 grid.SetPolys(elems);

or
         [...]
                 grid.SetStrips(elems);

In the first scenario computing the contours took 13s, in the second - 
182s. I also used vtkStripper to actually compute some longer strips. 
For 50e3 computed strips the contour filter took 34s to update. Much 
better, but still worse than when using individual triangles.

So my questions are
  - is there something I can do to improve the contouring speed? (is it 
parallelizable in current VTK version, for example?)
  - are there any other known performance issues when using triangle 
strips in filters?

Thanks a lot!

Marcin Krotkiewski