Thomas O
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 Mar 9 awarded Popular Question Jul 17 awarded Yearling Apr 30 awarded Favorite Question Sep 24 awarded Autobiographer Feb 20 awarded Notable Question Dec 3 awarded Good Question Apr 11 awarded Famous Question Oct 3 awarded Popular Question Jun 6 awarded Notable Question Nov 18 awarded Popular Question Oct 26 awarded Yearling Oct 3 awarded Nice Question Dec 4 comment Lat/Lon/Alt to spherical or cartesian coordinates @whuber: These errors are tolerable. Dec 4 awarded Teacher Dec 3 answered Find the best path along raster Dec 3 comment Quick way to determine if facing a given lat/lon pair with a heading Actually, I created a second question for this, because it sounds like a good optimisation: gis.stackexchange.com/questions/4147/… Dec 3 asked Lat/Lon/Alt to spherical or cartesian coordinates Dec 3 comment Quick way to determine if facing a given lat/lon pair with a heading Do you have any tips on converting the coordinates? The position of the viewer may move so these would have to be updated, but if the cost is only a few sin or cos calculations when the coordinates change it would probably be worth it. Dec 3 comment Quick way to determine if facing a given lat/lon pair with a heading @whuber: Yep, it's probably a better idea because the fixed point library also uses the 40-bit accumulators which support add, subtract, multiply, multiply-accumulate, euclidean distance etc. But these are only available on the dsPIC33F processors and I'm hoping to migrate to PIC24 after a while, which doesn't have these accumulators. So I might have to stick with floating point for now. It renders at about 20-30 frames per second, which is fast enough for me. Dec 3 comment Quick way to determine if facing a given lat/lon pair with a heading @whuber: My MCU manufacturer (Microchip) have a software fixed point Q16 library. I was considering using it; it might be faster. It has most trig functions.