[Paraview] Parallel Rendering vs Parallel Visualization

[Michael Wild]

On 29Apr, 2008, at 11:01, Cally K wrote:

> hi everyone
>
> I have a theory question to ask. Just would like to clarify some thing
>
> a) The difference between rendering and visualization,
> b) the difference between parallel rendering and visualization
>
> i have come across many papers on parallel rendering and also  
> visualization, and they all use Paraview, but what exactly is the  
> difference...,some are titled Parallel Visualization
> whereas some are titled Parallel Rendering, but they are all about  
> the same..( Hope someone could explain )
> Can i say that rendering is part of a visualization pipeline..? And  
> parallel rendering could mean.. parallel processing - different  
> processors involved in the rendering phase ... what would then  
> parallel visualization be ..?
>
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Rendering: the process of creating the visual representation of some  
data (e.g. for display on a screen). This often includes triangulation  
of the data, calculation of the lighting, etc. It is just about "how  
does it look".

Visualization: processing of raw data with the goal of making it  
"visible"/understandable in a visual (rendered) reperesentation. This  
usually includes as the last step rendering, but usually involves many  
more steps, such as computing derived quantities, extraction of  
profiles, iso-surfaces, etc.

Parallel rendering: rendering can be very expensive in computational  
terms. One reason can be the sheer number of triangles involved. Or if  
you have translucent media with non-homogeneous refraction index. So  
one might want to distribute the work to multiple processing units.  
I'm by no means an expert here, but I think this usually involves  
having several graphics chips (i.e. graphics cards) work in parallel.

Parallel visualization: not only rendering is expensive, but also the  
data processing before the actual rendering step. So of course one  
might want to distribute the load, using e.g. a computer cluster,  
multiple CPUs or one or multiple multi-core CPU(s).


I hope this helps (and is at least passingly accurate).


Michael