Darb Dabney’s OpenSim Blog

My open-source mental nodules have really had a feast these past couple of weeks. First, I had a great insight when I finally listened to a colleague who had spoken well of Ubuntu for some time. When I started using Feisty Fawn and got far, well, and with an attractive and performant result and little effort, I knew that things had evolved well in the past few months.

My previous favorite was a CentOS 4.3 upon which I installed a large commercial mapping package (ESRI ArcIMS 9.1) over Apache and Tomcat. The vendor supported an RHEL configuration and I got close enough for very few problems with CentOS.

But at the home lab, my hardware had to be wrung from random bits of machine that left me with a 1 GHz Celeron / 1.5 GB memory on an ABIT VH6T board, and a new 160 GB PATA disk. First I installed server, but then just relaxed and had Ubuntu Feisty just slide into place. My goal with this box was to dedicate it to OpenSimulator.org testing. In the process of getting Mono, LibSL, and OpenDynamicsEngine all built in place, I also elected to update to Gutsy Gibbon.

Late last week I got first one, then four OpenSim regions working with default starter islands. Next, I applied some spatial resources (ERDAS Imagine) to extract an appropriate amount of real-life digital terrain data. As I am wont to do with my RL-related builds, I scaled down my canyon of interest (Strawberry Canyon above the UC Berkeley campus) to 1/4 scale so it would fit on my four sims.

Just a few tweaks were needed for my extract.
First, ERDAS Imagine has a ton of export formats, and I ended up having success with the IEEE 32-bit floating point format, using swapped bytes (not unswapped, nor any specified -endian flavor).

When I had success, it took me a fiew minutes to realize that the sim was reading in X and Y in a swapped order from the RAW file, and so my terrain had a 90-degree counter-clockwise rotation relative to the original. My original is in WGS84 UTM zone 10 north meters, and has a two-meter posting interval so that it would have come in as a 1/2-scale terrain in OpenSim. I downsampled my terrain clip to a 4-meter interval and rotated it 90 degrees clockwise, then exported a 1K by 1K raw float as described above. It worked just fine and dandy for my first four sims.

Next I worked on a (now I know) naive goal of taking the correponding area’s orothoimagery to drape over my shiny new terrain. I prepared a co-registered 1K by 1K, 24-bit Targa file, then sliced it up into four tiles for my four sims. When I loaded it in using the Estate controls, was I ever surprised! Not only was my pixel-perfect texture tiled all over the place, I realized that there isn’t any way in the Estate controls to change that repeat.

Thanks to nebadon for helping me realize that there’s just no hope for the draped orthoimagery, before I tried too hard to find a magic tweak that wasn’t going to be there. I’ll be able to set up buildings in their proper places using orthoimagery on a sim-sized megaprim, so I’m not totally stumped.

But all in all, my open source nodules are overflowing with wondrous Ubuntu, Mono, and OpenSim progress this past week. I’ve also set myself a goal of modeling Mt. Tamalpais in time to make a poster for the AGU.org Fall Meeting in early December in San Francisco. If I tune the terrain along the fire roads, it might someday be possible to actually ride a virtual mountain bike around the summit of a 1/4-scale East Peak, on an 8 x 8 standalone set of sims.

Nuff for now: here’s Strawberry Canyon towards sunset. Four OpenSim regions with one continuous RL terrain.

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