Gocator Snapshot Sensors: User Manual
How Gocator Works • 38
Step 3: Use stereo correlation or independent triangulation to generate 3D point cloud
Gocator sensors are always pre-calibrated to deliver 3D data in engineering units throughout
their measurement range.
Clearance Distance, Field of Viewand Measurement Range
Clearance distance (CD), field of view (FOV),and measurement range (MR)are important concepts for
understanding the setup of a Gocator sensor and for understanding results.
Clearance distance – The minimum distance from the sensor that a target can be scanned and
measured. A target closer than this distance will result in invalid data.
Measurement range – The vertical distance, starting at the end of the clearance distance, in which
targets can be scanned and measured. Targets beyond the measurement range will result in invalid data.
Field of view –The the area on the XYplane along the measurement range. At the far end of the
measurement range, the field of view is larger, but the resolution is lower. At the near end, the field of
view is smaller, but the resolution is higher. When resolution is critical, if possible, place the target closer
to the near end. (For more information on the relation between target distance and resolution, see
Stereo Correlation vs. Independent Triangulation
Stereo correlation means that the sensor locates the same point on the physical target in the two images
captured at different viewing angles. Since the exact distance between the two cameras and the viewing
angles are known, the distance to the point can be calculated. In order for stereo correlation to work and
produce a 3D data point, the point on the target must be visible in both cameras. Stereo acquisition may
produce more stable measurements on targets with a simple shape, but will be affected by occlusions on
targets with complicated shapes and protruding features.
Independent triangulation means that each camera independently triangulates off the LED light pattern,
based on the calibration process that takes place when the sensor is manufactured. Since the Gocator
3x00 sensor has two cameras, a point on the physical target only needs to be visible to one of the
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