On Sat, March 17, 2007 3:21 am, belinda thom said: > > On Mar 16, 2007, at 4:17 AM, Douglas S. Blank wrote: > >> >> Yes, that text is more confusing than helpful. Here, "hit" is >> suggestive >> of the ray that extends from the range sensor and then intersects >> with an >> object in the world. So, the (x,y,z) tuple is the location (in local >> coordinates) where the sensor detected an object. > > So what do local coordinates refer to? Is this wrt some "central > spot" inside the robot?
Yes. The origin is the center of the robot. > I've read about the geometry stuff, in conjunction with your hits > explanation, but I'm still very confused on how to proceed. > > The reason I am asking these questions is that I'd like to be able to > write a method to ask if three adjacent position sensors are looking > at something that lies in the same plane (actually, along the same > line, since I'm using the 2d world). I'm currently doing some hacks > using sensor angles and distances, but that stuff isn't working the > way I'd expect. Then I started to think perhaps all this stuff is > already embedded (and debugged :-) in a local coordinates viewpoint, > which led me to wonder if each sensor shares the same underlying > local reference or not, and how to use this info to extract what I want. Take a look at pyrobot/plugins/brains/LPSWander.py which uses pyrobot/map/lps.py and pyrobot/map/gps.py to see how you could use geometry and hits. > FWIW, I've looked at, say robot.range[2].hit and robot.range > [2].geometry and there is exactly one element in these two tuples > that appear to have identical values (0.0299...). Planning ahead, the geometry and hits also have a z component, for height. Of course, this won't change for these sensors. -Doug > > > -- Douglas S. Blank Associate Professor, Bryn Mawr College http://cs.brynmawr.edu/~dblank/ Office: 610 526 6501 _______________________________________________ Pyro-users mailing list [email protected] http://emergent.brynmawr.edu/mailman/listinfo/pyro-users
