Patent ID: 6512838
Filing Date: 2003-01-28
Classification: G01C,G01S,G06F,G06K,G06T,H04N

Abstract:
For use with a system that acquires distance and brightness measurements using energy transmitted from an emitter at a first location on a plane, said energy reflecting at least in part from a target object and being detected by independent sensors defining a sensor array on said plane but spaced-apart from said first location, a method of improving actual (x,y,z) measurement by correcting elliptical error of a system including said energy transmitter and sensor array, the method comprising the following steps:(a) defining a spherical coordinate for said sensors in said sensor array, and constructing a look-up table containing spherical coordinates for each of said sensors, where a spherical coordinate for sensor Pij is given by (pij,âˆ’aij,âˆ’bij); (b) defining a spatial coordinate of said emitter from a spherical coordinate system defined in step (a) such that said spatial coordinate of said emitter has a same origin as said spherical coordinate system, where said spatial coordinate of said emitter is (Cx, Cy, Cz) and defining a constant k as square of distance between said emitter and said origin of said spherical coordinate system; (c) For each sensor Pij, constructing a look-up table of a constant hij where hij is calculated as follows: â€ƒhij=2(pij+Cx cos(aij)sin(bij)+Cy sin(aij)sin(bij)+Czcos(bij))where (pij, âˆ’aij, âˆ’bij) is the spherical coordinate of said sensor Pij defined at step (a), and where (Cx, Cy, Cz) is the spatial Cartesian coordinate of said emitter defined at step (b);(d) identifying sensors {circumflex over (P)}ij that actually detect energy reflected from said target object; (e) using measured rountrip distance dij from said emitter to sensors {circumflex over (P)}ij identified at step (d) to calculate distance rij from an imaging portion of said target object and said sensor {circumflex over (P)}ij according to rij=((dijâˆ’pij)2âˆ’k)/(2dijâˆ’hij), using values of k determined at step (b), values of hij determined in step (c), and {circumflex over (p)}ij determined in step (a); and (f) calculating actual Cartesian coordinate (Ax, Ay, Az) of imaging portion of said target objection according to Ax=rij cos(Ã¢ij)sin({circumflex over (b)}ij), Ax=rij sin(Ã¢ij)sin({circumflex over (b)}ij), and Ax=rij cos({circumflex over (b)}ij), where rij is obtained in step (e) and Ã¢ij, {circumflex over (b)}ij of sensor {circumflex over (P)}ij are obtained in step (a).