Jun 01 2008

Getting Physical with OpenSim 0.5.7_4952 – ODE with 40-region Standalone

Published by at 2322h under OpenSim

After learning how the terrain sculpties could be handled by Meshmerizer if running a physics engine like Open Dynamics Engine (ODE), I have taken a couple of weeks to proceed slowly, cautiously as I bulk up the demands on the hardware. After all, my original notion of doing large swaths of real-life terrain on a single standalone sim was based on loading that terrain into the regions then using only Basic Physics to reduce the load.

But in the months since I first started loading real terrain (starting with Mt. Tamalpais in 200710), truly phenomenal, awesome progress has been made in how efficiently OpenSim runs for me on Ubuntu/Mono. Sure, at new year 2008 my OpenSim test environment upgraded from a P3-800/1.5 GB Coppermine system to an E6550-3.4 GHz/4 GB system. But what was limiting last Fall was the chatter among the various regions, so that I could add more: 49, 81, 100 regions–but then the CPU load with no client logged in would hum up toward 70%, and running a physics engine would be a challenge with many fewer regions.

These days, that seems like a stone-age experience. The rate at which regions now load on startup is incomparably faster (even on the old Coppermine), and the chatter is almost nil–no clients logged in looks truly quiescent at 1% to 2% CPU. All this has emboldened my interest in trying ODE again. And that experience likewise is so much better. Time was, there was reason to visit the ODE site and build one’s own, and even then stuff could get strange. I was inspired by the videos that Nebadon posted showing many hundreds of blocks falling. But I experienced things like tripping over what felt like a singularity that shot my unfortunate avatar hundreds of meters into the air, bouncing like some tire that fell off of a jet after takeoff. That was then.

Now I see Ruth’s legs bend a little bit under the effects of gravity, but I do have 40 regions humming along in standalone with quiet-state CPU load of 2% to 5%. So I have plenty of reason to expect that I’ll be able to do this with the 40-region model, using terrain sculpties that are physical as long as they don’t tilt over against the terrain surface like they do in the SL Agni grid.

Video demo of Ruth narrowly avoiding getting squished by a 10-meter cube
If you’ve got the embed blocked, the link should be http://www.youtube.com/v/Jz9234jYbkw

My next goal for Open Berkurodam is to generate a new surface. I may have a good copy of what is called categorized or classified LiDAR data, where individual points in a cloud are tagged with an estimate of whether they are from bare earth, tree crown, rooftop, and such. This sort of LiDAR data should support the sort of grid that is not just bare-earth terrain, but actually has the proper size, shape, and height bump for every tree and building. This would be ideal for draping with the orthophotography, because within the limits of parallax that have been corrected in the orthoimagery, every building should sort of take shape on its own.

I don’t hold any fantasy that things will look properly immersive right on the classified LiDAR grid, but I have a sense that there will be enough detail to guide a reasonably accurate build with just a bit of training on the part of the builder to recognize their way past registration artifacts–where the bump from the LiDAR surface doesn’t align with the roof part of the orthoimage.

To bring this to a presentable stage, I hope to somehow have a live version of the 40-region UC Berkeley and vicinity 1.024:1 model with classified LiDAR surface on physical sculptie megaprims, on a public server by mid-July.

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