Derivation: x1 = 309px x2 = 128px x1' = 15" x2' = 0" Z ~ Avg(35",39") = 37" dx = x1 - x2 = 309px-128px = 181px dx' = x1' - x2' = 15" - 0" = 15" C = dx/dx' = 181px / 15" = 12px/inch dx' = dx / C dx' = dx / 12 This equation works only at Z = 37" If we double the distance to 74" Each pixel corresponds to more inches dx' = 2 * dx / 12 So, for the general equation dx' = (Z/37") * dx / 12 General equation dx' = (Z/37") * dx / (12px/in) dx' = Z * dx / (12*37) dx' = Z * dx / 444 Validate Equation dx' = Z * (x4-x3) / 444 dx' = 60 * (420-323) / 444 dx' = 60 * 97 / 444 dx' = 13" dx' = x4'-x3' = 15"-0" = 15" ~ 13" Check ---------------------------------------------------- Data Points: World Coordinates Point 1 Blue zDistance 0 x 0 y 0 Point 2 Black zDistance 0 x -15" y 0 Point 3 White zDistance 14" x 0 y 0 Point 4 Red zDistance 14" x -15" y 0 Point 5 Blue zDistance 0 x 0 y -10" Point 6 Blue zDistance 0 x -15" y -10" Screen Coordinates Cam 1 (RGB) Point 1 Red 51 Green 40 Blue 72 x 382px y 256px Point 2 Red 5 Green 0 Blue 6 x 274px y 233px Point 3 Red 147 Green 127 Blue 120 x 420px y 209px Point 4 Red 34 Green 0 Blue 0 x 323px y 201px Point 5 Red 0 Green 1 Blue 6 x 384px y 334px Point 6 Red 7 Green 5 Blue 16 x 278px y 311px Screen Coordinates Cam 2 (Depth) Point 1 zDistance 153-1.3*81=48" x 180px y 130px Point 2 zDistance 153-1.3*77=53" x 120px y 120px Point 3 zDistance 153-1.3*74=57" x 215px y 100px Point 4 zDistance 153-1.3*69=63" x 155px y 095px Point 5 zDistance 153-1.3*78=52" x 180px y 180px Point 6 zDistance 153-1.3*73=58" x 125px y 160px