Positioning and reference grid
Posted: Mon May 18, 2009 5:30 pm
I don't understand how the coordinates work.
I put the vector clip on the ground at say, 12 inches from the sensor. I get a certain z value (using the OptiTrack SDK). Then, I move the clip left and right, although I make sure to stay at the same distance along the z-axis, and my clip is always facing forward, i.e. along the z-axis (NOT toward the sensor). This makes my z value change by up to 40 mm. Why does it do that? Lens geometry that is unaccounted for?
Also, I noticed that at a same position, if I just rotate the clip around the y axis (yaw rotation) where the rotation point is the point halfway between the 2 front reflectors of the clip, my x and z values change radically. Does this mean that the x, y, z reference grid follow the orientation of the clip? Or is the x, y, z grid relative to the sensor?
I put the vector clip on the ground at say, 12 inches from the sensor. I get a certain z value (using the OptiTrack SDK). Then, I move the clip left and right, although I make sure to stay at the same distance along the z-axis, and my clip is always facing forward, i.e. along the z-axis (NOT toward the sensor). This makes my z value change by up to 40 mm. Why does it do that? Lens geometry that is unaccounted for?
Also, I noticed that at a same position, if I just rotate the clip around the y axis (yaw rotation) where the rotation point is the point halfway between the 2 front reflectors of the clip, my x and z values change radically. Does this mean that the x, y, z reference grid follow the orientation of the clip? Or is the x, y, z grid relative to the sensor?