ΒΆ Point clouds
PCS software is designed to be used with LAS files. LAS is an ASPRS standard used for storing point clouds. PCS can use the 1.2 or 1.4 version of the LAS file, but according to experience, the 1.2 version is the most common. Most post-processing environments export to LAS files and other common software are also compatible with this format (CloudCompare, QGIS, AutoCAD, Microstation, etc.).
To be able to use the point clouds, an optimisation is needed before loading them into PCS. The optimisation process takes the LAS file and reorders the point cloud using a quadtree matrix to read and visualise points faster. This action shall be carried out for every LAS file before the first use. If the LAS file is being modified after the optimisation, it shall be optimised again. After the optimisation, the cloud can be loaded into the software.
There is no limitation in the LAS file size that can be loaded to PCS, but it is highly recommended that the cloud be optimised before opening it in the software. Using smaller LAS files, up to a few GB, is recommended. Using a single big LAS file might lower the software's performance. If the user has a single LAS file, the external optimizer tool can be used to tile the LAS files into smaller chunks, making it faster to use.
Above LAS files, the software can handle text-based point cloud formats, which can be converted to LAS using PCS tools.
The software does not support the e57 point cloud format. The e57-LAS converter is in the development phase, which will be able to extract the point clouds into LAS files and the images to TopoDOT IPRJ format.
LAZ files are also supported as of 2023. The LAZ files can be dragged and dropped to the software directly or opened using the Open Cloud option from the project explorer by entering *.laz to the filename and pressing enter. The user can select the LAZ files from the browse window. PCS can also handle non-optimised LAZ files, but in this case, the 2D view can visualise the point cloud above 1:50 scale as fragmented. We recommend optimising the LAZ files as well; in this case, they operate the same as LAS files. PCS will not apply the LAS Settings upon opening an LAZ file, which means if the user - by default - optimises not optimised files, it will not be performed on LAZ files.
If users are more comfortable with LAS files, it is recommended that LasZip be used to convert LAZ files to LAS files.
The software - in general cases - loads only a part of the point clouds to the memory. The user can change this setting in File/LAS Settings or when opening a file or using the right-click menu on the LAS file(s). If some of the points are loaded into the memory, the user cannot modify or classification of the cloud. If the user wants to classify the cloud, all points shall be loaded into the memory. It is impossible to load more GB of LAS files into the memory than the physical RAM installed on the PC. For example, if the used desktop has only 16 GB of RAM, no more than 16 GB of LAS can be loaded to the project with all points in the memory setting. Using all points in the memory option is recommended to be used up to 80% of the installed RAM capacity, as the Windows system also consumes RAM, and overloading the RAM might crash the desktop.
If all points are loaded to the memory, it is possible to modify the classification of the points and save the modifications to the source file. Even if it's available in the right-click menu, saving is irrelevant for point clouds if only part of the points are loaded into the memory.
The class information is only one attribute which can be used and modified in PCS software. The software can read and utilise the following LAS point attributes:
- XYZ coordinates
- Intensity
- Number of returns
- Return number
- Classification
- Scan angle range
- User Data
- Source ID
- GPS time
- RGB values