Coordinate Systems

Data points are reported in one of two coordinate systems, which depends on the alignment state of the sensor.

Unaligned (sensor) coordinates: Used on unaligned sensors.
Aligned (system) coordinates: Used on aligned sensors.

Understanding coordinate systems is an important part of understanding measurement results. These coordinate systems are described below. For information describing the orientation of the axes used by your sensor, see Sensors.

Unaligned Coordinates

Unaligned sensors use sensor coordinates, that is, the coordinate system is relative to the sensor itself. The measurement range (MR) is along the Z axis. The sensor’s field of view (FOV) is along the X axis. Most importantly, the origin is at the center of the measurement range and field of view, in other words, the center of the scan area.

The Y axis represents the relative position of the target part in the direction of travel. Y position increases as the target moves forward (increasing encoder position). Typically, the direction of travel of the target is opposite the sensor's positive Y axis. If it isn't (due to the orientation of the sensor's mounting), you need to configure the sensor's orientation to be "reversed." For more information, see Creating a Sensor System.

Aligned Coordinates

Understanding aligned 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. 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 System > Alignment page. Note that currently, you can ignore Sensor Group Transforms, which represent the transformations between groups of sensors; support for this will be available in future versions of the sensor software. For more information on transformations in the web interface, see Transformations.

In aligned coordinates, the 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.