This article explains how to manually classify the point cloud using the standard of the American Society for Photogrammetry and Remote Sensing (ASPRS).
IN THIS ARTICLE:
How to assign selected points to a class
How to show/hide individual or all classes
How to show classes in RGB
How to export all classes
How to assign selected points to a class
Assigning points between different classes is especially useful when:
- The point cloud is not classified, and certain points need to be assigned to classes.
- Points are not assigned to the correct point class.
To manually assign points to a class:
- Use the Selection tool to select points. These selection tools could be:
- Rectangle selection (keyboard shortcut R)
- Polygon selection (keyboard shortcut J)
- Right-click on selected points.
- Click to Assign to ASPRS class to assign selected points to an ASPRS class.
The ASPRS class standards identify each class using an ID number. This is the order ASPRS follows to ensure that the classification encoding is homogeneous.
(https://www.asprs.org/wp-content/uploads/2010/12/LAS_Specification.pdf)
Disclaimer: Pix4D publishes this information as a courtesy to its customers. Pix4D makes no warranty of any kind, expressed or implied, with respect to the content's validity or accuracy.
This ID can be changed in PIX4Dmatic for each custom class individually to adapt the classification ID in the project. The standard classes can't be modified. 
How to show/hide individual or all classes
If the ASPRS classes option is enabled, it is possible to show or hide each class. In case one or more classes have to be displayed or hidden, this can be done individually by clicking on the display icon(
).
Tip: To achieve optimal classification results, it is advisable to hide any class that is not relevant. This will help easily identify points that remain unclassified.
How to show classes in RGB
The point cloud keeps the RBG colorization even when the point cloud is classified. To see each class on RGB color, instead of the ASPRS class is necessary to disable Show class in RGB (
) to switch to RGB color. In the opposite way, if the option is enabled (
) the colorization is related to ASPRS class.
Note: ASPRS is a standard with defined colors by class, but it is also possible to change these colors in case a different color schema is needed.
How to export all classes
Exporting a classified point cloud is the same process as a non-classified point cloud. There are two ways to do the export:
-
- Navigate to Processing options > Exports > Dense point cloud and click on the More
.svg)
button or - File > Export > Dense point cloud
- Navigate to Processing options > Exports > Dense point cloud and click on the More