PMW3901/PAA5100 optical flow pixel to distances

optical_flow_equation.py

            # h = height/altitude of the sensor from ground
            # fov = field of view of the sensor in radians
            # res = resolution of the sensor in pixels
            # scaler = scaling factor
            # dt = time period of this loop
            
            conversion_factor = h*2*np.tan(fov/2)/(res*scaler)

            if 'paa5100':
                # Convert data from sensor frame to ROS frame for PAA5100
                # ROS frame: front/back = +x/-x, left/right = +y/-y
                # Sensor frame: front/back = -y/+y, left/right = +x/-x
                dist_x = -1*conversion_factor*delta_y
                dist_y = conversion_factor*delta_x
            elif 'pmw3901':
                # ROS and Sensor frames are assumed to align for PMW3901 
                # based on https://docs.px4.io/main/en/sensor/pmw3901.html#mounting-orientation
                dist_x = conversion_factor*delta_x
                dist_y = conversion_factor*delta_y
                        
            abs_dist_x += dist_x
            abs_dist_y += dist_y
            
            vel_x = dist_x/dt
            vel_y = dist_y/dt