[vtkusers] Large Memory Datasets with VTK, & Problems with the ReleaseDataFlag

[John Biddiscombe]

Randall

> I have a dataset of 1-billion points (1k x 1k x 1k, StructuredPoints,
> 1scalar per point) that I've been trying to visualize via Flow Glyphs
> (simple Sphere glyph at each point, mostly just to test the memory
>  
>
I'm not going to answer your main memory related questions, but I've 
just uploaded a tarball, which you may find it interesting to play with, 
here,

ftp://ftp.cscs.ch/out/biddisco/CSCS.tar.gz

inside is a class called vtkOpenGLPolyDataPointSpriteMapper - this class 
will let you render a sphere using OpenGl's GL_ARB_Point_Sprite 
extension (or the NVidia equivalent one)

It's still not a finished (in the sense I want to add more features), 
but it can be used for real world problems. I've had a million spheres 
at a frame rate of about 15fps on this machine, and 10million at 0.5fps 
(a long way from a billion, but I'm hoping to get it going on the sepia 
cluster). You seem to be rendering volume data, so perhaps a volume 
renderer would be more suitable - this class takes polydata as input.

The class can be used in 2 modes
Accumulate (see this animation for an example 
ftp://ftp.cscs.ch/out/biddisco/Galaxy_4b_640x480.avi about 7MB)
Basically, gaussian blobs are used, and we enable blending and turn off 
depth buffer, blending uses (GL_SRC_ALPHA,1) so all RGB sums to produce 
a nice galaxy type view

Occlude mode : For hard spheres. Typical particle simulation stuff. 
Waiting for big dataset before producing movie.

See the tcl tests in the tarball for examples of usage.

Code tested on windows and linux today, so it should work.

I welcome feedback and improvements to the class.

JB

-- 
John Biddiscombe,                            email:biddisco @ cscs.ch
http://www.cscs.ch/about/BJohn.php
CSCS, Swiss National Supercomputing Centre  | Tel:  +41 (91) 610.82.07
Via Cantonale, 6928 Manno, Switzerland      | Fax:  +41 (91) 610.82.82