System Coordinates

Understanding system coordinates is important for two reasons. First, they are the direct result of performing the built-in alignment procedure. Second, they change how scan data is represented and how measurement results should be interpreted.

Performing the built-in alignment procedure on sensors adjusts the coordinate system in relation to sensor coordinates, resulting in system coordinates (for more information on sensor coordinates, see Sensor Coordinates). For more information on aligning sensors, see Aligning Sensors.

The adjustments resulting from alignment are called transformations (offsets along the axes and rotations around the axes). Transformations are displayed in the Sensor panel on the Scan page. For more information on transformations in the web interface, see Transformations.

System coordinates are aligned so that the system X axis is parallel to the alignment target surface. The system Z origin is set to the base of the alignment target object. In both cases, alignment determines the offsets in X and Z.

Alignment is used with a single sensor to compensate for mounting misalignment and to set a zero reference, such as a conveyor belt surface.

Alignment can also determine offsets along the Y axis. This allows setting up a staggered layout in multi-sensor systems. This is especially useful in side-by-side mounting scenarios, as it provides full coverage for models with a small scan area.

As with sensor coordinates, in system coordinates, Y position increases as the object moves forward (increasing encoder position).

Alignment also determines the Y Angle (angle on the X–Z plane, around the Y axis) needed to align sensor data. This is also sometimes called roll correction.

Y angle is positive when rotating from positive X to positive Z axis.

Similarly, tilt can be determined around the Z and the X axis, which compensates for the angle in height measurements. These are sometimes called yaw correction and pitch correction, respectively. Intentional rotation around the X axis is often used for specular mounting, that is, for scanning targets that are shiny or reflective. Note however that X angle correction can't currently be corrected for using the alignment procedure available on the Alignment panel. X angle can only be manually entered in the Transformations panel. For more information on transformations in the web interface, see Transformations.

X angle is positive when rotating from positive Y to positive Z. Z angle is positive when rotating from positive X to positive Y.

When applying the transformations, the data is first rotated around X (clockwise, with the X axis toward the viewer), then Y (counterclockwise), and then Z (clockwise), and then the offsets are applied.