On Sat, Feb 20, 2010 at 2:01 AM, John Smith <[email protected]> wrote: > On 20 February 2010 00:05, Nick Hocking <[email protected]> wrote: >> 1) compass,gps, high school maths. >> 2) theodalite, professional gps and a real live surveyor. >> 4) laser rangefinder + gps > > These are all the same method, just slightly different tools... and #4 > still needs a direction/compass... >
The laser range finder + gps method is quite different from compass + gps / other surveying methods. Instead of drawing lines from measured gps points according to measured compass bearing and finding the intersection point, draw circles with radius of measured distance around the measured gps points and find their intersection. >> 3) photographic techniques >> 5) audio tracking ??? > > How would either of these methods help? > Disclaimer: I'm not sure of the practicality of the following ideas but I think they are interesting. Photographic techniques: you can use photographic images in place of compass bearings with some calibration for the field of view. You need to be able to take photos of several distinct landmarks with known positions and then it would be possible to correlate the angle of view between two objects in an image with the number of pixels between them. Then you can take images of the wind farm (for instance) from several different locations, determine the angle of view between pairs of towers from these different locations and from there calculate their position. There are a few potential problems with this scheme: a) each object needs to be correctly identified in each image, a version of "correspondence problem" in machine vision (and this could be tricky when you have a dozen or more objects of nearly identical appearance) and b) the lens settings need to be consistent between all the images which probably requires manual control of camera settings and is easier with a fixed focal length lens. Anyway, I think you could make this work, but I'm sure a compass would be simpler and more efficient. Arie. _______________________________________________ Talk-au mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-au
