Abit TX5 User's Guide download pdf (Page 54)

4 Getting Started

Targets should not be positioned symmetrically. They should form a polygon around the

scanner and have varying distances to the scanner. Place them in the scanning area at varying

heights, distances and planes. Avoid placing the targets in a straight line.

If the references cannot be placed in an adequate distance to the scanner, increase the

scanning resolution or the size of the targets.

Do not place targets in close proximity to one another. The distance between targets should

not be smaller than 1m.

Make sure you see the targets in more than one scan (if you do not have surveyed coordinates

for each targets). A target which is only visible in one scan is useless for registration.

When capturing a chain of scans resulting in a tubular point cloud which is typical for e.g.

tunnel surveying, it is recommended to make use of the inclination sensor and references with

surveyed coordinates. Such references should be used along the entire chain. The scanner has

a certain measuring uncertainty and if you do not use surveyed references when capturing and

registering a chain of scans, this measuring uncertainty may propagate from scan to scan.

Checkerboard Targets

The angle of incidence between the laser beam and checkerboard targets should not be smaller

than 45°.

Depending on the chosen scanning resolution, the detection of checkerboard references in the

scans by the TX5 SCENEsoftware may be unreliable beyond a certain distance to the scanner.

For example, when using A4 checkerboard references and scanning with a resolution of 1/4, the

distance to the scanner should not be greater than 15m. Larger distances can easily be

achieved by enlarging the size of the target or scanning with a higher resolution.

Checkerboard targets should not be rotated by 45° in relation to the scanner's axis.

Have sufficient scan points on the checkerboard targets. They need four or more scan points

per quadrant.

Checkerboard targets should not be attached to a curved surface.

Reference Spheres

Reference spheres should be completely visible in the scan. Make sure that they are not partly

covered by other objects.

Depending on the chosen scanning resolution, the detection of sphere references by the TX5

SCENEsoftware may be unreliable beyond a certain distance to the scanner. For example, when

scanning with a resolution of 1/4 and using spheres with a diameter of 145mm, the distance to

the scanner should not be greater than 18m. If you are using larger spheres, for example

spheres with a diameter of 200mm, the distance to the scanner may be extended to 45m.

For more information on registering scans and using references for registration, refer to the Trimble

TX5 SCENESoftware User Guide.

Trimble TX5 3D Laser Scanner User Guide 54

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Abit TX5 User's Guide Page 54