Archive for April 16th, 2008

Apr 16 2008

The toils of OpenBerkurodam

Published by under SL In General

Somehow, things are harder at full scale than they were just a few months ago doing 1:4 work in OpenSim 0.4 for all of Berkeley. The new OpenSim 0.5.4 has some aspects, like initial launch, that are blazingly fast. Still, I struggled with what surely acts like lazy instantiation in the new code. It launches like a rocket, but when I touch it with a client, lots of the same old slogging starts to happen. Very much most significantly for my extensive and largely static work, the current 0.5.4 will not configure stably for more than 35 regions on one (dual-core) server, even with BasicPhysics.

So, after fighting with it for three days, rolling back toward 0.5.0, and finally flopping down to tonight’s SVN trunk, I have reached a spatial compromise that can be shared. I really wrung my heart out trying to pare down the 40-region design posted last week into an “essential” 35 or fewer regions, balancing the virtues of demonstrating 1:1 scale paraverse work in a relevant way to students, Cal faculty, and City government interests. After hours of exploring options, I threw out the northernmost eight regions, to leave a 4×8 array of 32 regions that retain (somewhat selfishly) the Martin Luther King Jr. Civic Center Building, as well as the California Memorial Stadium (for Hayward Fault interests), the Greek Theater, and the Berkeley Community Theater (for musical memories’ sake).

The terrain is of the finest quality for use in OpenSim. I took Alameda County LiDAR-based bare-earth terrain in triangulated irregular network (TIN) form, and using the ArcGIS 9.2 3D Analyst extension, ground out a 30-cm posting interval grid version, in WGS84 UTM 10 north meters, NAVD88 Geoid2003 meters, for processing in Leica Geosystems ERDAS Imagine 9.1 to produce diced tiles that were flipped and exported to raw single-precision floating point, byte-swapped (Motorola style) raw binary terrain tiles that OpenSim so readily digests. To implement my chosen 1.024:1 well-tempered scale, each “1-meter” terrain sample in the sim was actually 976.5 mm in sample interval, simply taking 256 samples over 250 meters of real-world terrain for each sim X- and Y- axis. Thus far, I have neglected to scale the Z in the same way, but when I get to stamping out the terrain megaprims, and need to rescale the terrain for best fit, I’ll rescale.

Here’s two views of the sim running on a dual-core 3.4 GHz server (Ubuntu 7.10 / Mono). One view from the Synchotron building area of Lawrence Berkeley National Lab, at the northeasterly corner of the sim, looking southwesterly.

Open Berkurodam 32-region terrain view from NEly corner

The other view shows how incredibly detailed and appropriate the LiDAR terrain is when used in 1:1 scale OpenSim application. The view is from near the SEly corner of the sim, and shows the bare-earth expression of the California Memorial stadium, the Greek Theater, and Bancroft Ave running westerly, as visible by its smooth, crowned road grade and gutters, all plainly visible in the terrain.

CA Memorial Stadium, Greek Theater, and Bancroft Ave in Berkeley

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