Stephen Northcott wrote:
Dear all,
I wonder if a few people who are more familiar with getting the best
performance out of OSG can make some suggestions..
Some background on my problem..
I am visualizing a pipeline using ultrasonic readings from the inside
of the pipeline.
There are two items of data. The distance from the inside wall and the
outside wall back to the center, repeated many times around the
pipelines circumference..
To get any kind of decent resolution out of this pipe data we rotate
our sensor around 400 times in a 1 meter length, and take 400 readings
for each revolution. That makes a total of 160,000 individual readings
I am representing in OSG to give us that 1 meter length of pipe.
If I simply take those 160,000 lengths of data and render them as unit
cubes, stretched to the length of the distance between the inside of
the pipe and the outside and then make a scene graph with them all
arranged into the form of the pipe.. it makes a great visualization,
but makes a massive scene graph which has very high overheads for
culling and actually rendering also. Not unexpectedly as it's not very
efficient..
Now, I do plan to work on optimizations by pre-processing this data,
having 'stretched unit cube' model data in look up tables so that I
don't have to make 160,000 individual unit cubes, and looking for
repeat patterns and so on in the data that can be modeled as something
other than unit cubes... But in theory we could end up with a length of
pipe with 160,000 truly individual readings in each 1 meter length, and
as such I want to be able to render that as quickly as possible for the
worst case scenario.
Can anyone suggest some areas in OSG I should be looking to get this
high object scene to cull and render any quicker?
Thanks for any pointers to material that you feel is relevant.
I'm far from an expert but you would probably do better to batch your
geometry into larger shapes. For example, instead of having 160,000
cubes at 6 quads each bundle them together into 1,000 160*6 quad shapes.
Others will chime in I'm sure, but I think it's the 160,000 trips to
the graphics card that is going to kill you. By creating fewer more
complicated shapes you have fewer trips and you let the card do what
it's really good it.
I've probably not explained that well but hopefully you get the idea.
-Paul
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