Station:
Location where the points were measured from.
Different scanners have different processes for handling this.
Scan:
Combination of an individual Point Cloud and Station
A scan produces a point cloud.
Registration:
How a scan joins to another scan and is positioned
Can be done automatically or manually
Registration sets:
When scans are registered together they become a registration set.
Multiple registration sets can exist in a project
Point Cloud:
A point cloud is a set of data points in space.
The points represent a 3D shape or object.
Each point has its set of X, Y and Z coordinates.
Images:
Photos captured during the scanning process.
Panoramas are also generated from the images captured.
Colourising:
Applying colour to the Point Cloud
Done as a secondary process by overlaying the point cloud against the images and giving the point the colour it overlays.
Levelled scans:
Scans where levelled has been determined while scanning.
Unlevelled scans:
Scans that don’t have any level information associated with them.
Refinement:
Final tightening of the whole point cloud.
Errors:
Refers generally to mismatching of scan data.
Can be small (mm) or large (m)
Most errors can be minimised through observing best field practices or post processing.
Understanding the different types of registration is important to understanding errors.
Shadowing:
Scanning can’t see around, through or behind objects.
Shadowing occurs in scans when an object blocks the scanning of data behind it causing a “shadowing” effect in the point cloud
Ghosting:
When scans don’t match up properly
Visually several elements seem to occur in the same location
- Noise:
Points that are picked up in scanning data that are either low precision results or points that are not desired in the final output.