Merger Tool

The Merger Tool combines information from two cameras in multi camera set-ups. These set-ups, where two cameras are observing the same scene but from different orientations, are common in order to minimize the occlusions or shadows of the acquired RangeMap. The occlusions can be removed when the corresponding shadowed areas exist only in one camera (see following figure).

Occlusions problem: Invisible areas (or shadows) produced by the object's shape

Merger input data

The Merger tool accepts range maps obtained from the following laser triangulation layouts:

• 3D Camera (range map)
• 2D Camera + SAL3D Software peak detector
• 2D Camera + User peak detector

In both cases, the Merger tool requires, at least, two cameras.

This tool is not intended for merging information from cameras pointing to different parts of the scene e.g. for increasing the field of view of the acquisition system (see the following figure).

Merger configuration; a) Good configuration: both cameras are observing the same area, b) Bad configuration: both cameras are observing different areas.

Similar to the Metric Calibration Tool, the Merger Tool requires some parameters to combine profiles from two cameras in a single profile. In order to extract these parameters, a procedure similar to the Metric calibration (in which a pattern object is scanned) is required, involving the same considerations, but acquiring from each camera. The user is referred to Description of the linear calibration pattern to get more information about the pattern dimensions and positioning.

Warning:

The Merger Tool calibration is not able to correct any Lens Distortion. Please make sure you use the suitable optics.

Merger tool considers the camera region of interest, so, acquisition system must be recalibrated in case the camera ROI is modified.

One of the cameras is considered as the base (or reference) camera, while the other one is named the auxiliary camera. Naming one camera base and the other auxiliary, relates the Merger calibration with the Merger Profile combination. The Profile combination will return a single profile in coordinates of the base camera profile, with less shadows, and usually with less noise, as the redundant information can be averaged.

After computing the merger parameters, each Profile of the auxiliary camera can be merged with its corresponding Profile of the base camera. As the Merger tool works with profiles, image captures from both cameras must be synchronized, so both profiles are acquired with the object in the same position under the laser. When the scanned object is moving, this requires a time synchronization on camera trigger (e.g. Triggering both cameras at the same time with the signal from the encoder).

Example of the RangeMap obtained after merging: a) RangeMap of the base camera; b) RangeMap of the auxiliary camera; c) Merged RangeMap