Filtering with Boundary-Based Mobile Mapping Data

December 21, 2022

To easily filter point cloud data with a bounding frame derived from an alignment, follow this step-by-step guide using Trimble^® MX9 mobile mapping data and Trimble^® Business Center version 5.81.

Application Scenario

This example demonstrates how to filter out the non-relevant points of a 3D point cloud dataset. The remaining data can then facilitate 3D navigation using other tools, or can be exported once assigned to a region.

The following screenshots represent a typical mobile mapping point cloud dataset where, together with road data, other non-necessary elements from the surroundings have been captured, like trees, buildings, and more.

To remove the unnecessary dataset, you will use bounding polygons. There are different options to define a bounding polygon. In this example, the polygon is defined by an alignment with right and left offsets. The reference alignment could also be the centerline of the road. In this example, a generic polyline was used for the alignment definition.

Tools & Procedure

First, define the Boundary frame. From the CAD ribbon, under the Linestring icon, select Create Boundary. From the Create Boundary feature menu, provide a name to the bounding frame and specify the layer where the boundary should be saved. Specify the type of usage.

In the creation method, select the Alignment corridor option. This will enable the corridor creation wizard. If a reference alignment doesn’t exist yet, select New in the alignment from the Alignment Corridor box as shown.

The Create Alignment tools window is displayed. Assign a name to the new alignment and specify the layer where the alignment should be saved. Then, specify how to define the Horizontal Geometry Definition. In this example, an existing line was used. When the existing line is selected, click Ok.

The 3D alignment is now created, and its parameters are displayed in a dedicated spreadsheet.

Toggle back to the Create Boundary window. The new alignment is now loaded in the Alignment Corridor box. Specify a Left and a Right offset. The Left offset (respect to driving direction) is defined by adding a negative (-) sign as prefix.

The start and end of the bounding frame can also be defined with a starting and an ending station along the alignment. If this information is not provided, the bounding frame will cover the complete length of the alignment. Click on Apply to confirm.

The point cloud data inside the bounding frame is now selected. If needed, this selection can be assigned to a point cloud region.

Alternatively, from the Point Cloud ribbon, select the Keep-In option to remove all the points that are not inside the bounding frame. The following screenshot shows how data would look like in the Plan View and in the 3D View.