LiDAR

The LiDAR toolbox works on point clouds: the millions of individual returns a laser scanner records, each with a position, an intensity and often a classification saying whether it hit the ground, a building or vegetation.

Its 64 tools cover the whole chain, from inspecting a raw file to producing the terrain and canopy rasters you actually map with. They come from the Whitebox analysis suite and run entirely in your browser.

Point clouds are different

Everything else in the ToolBoxes panel works on layers you can see. A point cloud is different in three ways worth knowing before you start.

It is big. A single tile can hold tens of millions of points. Since the computation happens in your browser’s memory, start with a clipped or thinned file rather than a full survey.

It is not a map layer. Most of the tools here read a LAS or LAZ file and write another one, which is downloaded rather than added to your map. The tools that produce a raster or a vector layer, in Interpolation & Gridding, are the ones that put something on the map.

Classification is everything. Nearly all useful work depends on knowing which points are ground. That is what the ASPRS classes encode, and what the tools in Filtering & Classification produce when your file arrives unclassified.

The usual order of work

1. Look at the file. Lidar Info reports the point count, the extent, the classes present and the return distribution. It takes seconds and tells you whether the data is already classified, which decides everything that follows.
2. Clean it. Remove the noise classes, the outliers and the grazing angle returns.
3. Classify it, if the ground is not already identified.
4. Normalise it, so each point carries its height above the ground rather than its absolute elevation. That is what turns a point cloud into a vegetation and building height model.
5. Grid it into the rasters you will map: a terrain model from the ground points, a surface model from the highest returns.

The sub toolboxes

Sub toolbox	What it is for	Tools
Analysis Metrics	Inspect, describe and measure a cloud: density, statistics, tree detection, rooftops.	14
Filtering & Classification	Remove what you do not want, classify what is left, normalise heights.	22
I/O & Management	Convert, merge, tile, sort and split files.	12
Interpolation & Gridding	Turn points into rasters, contours and meshes.	16

Getting a point cloud in

Load a LAS or LAZ file through Add Data, or browse one from your computer directly in a tool’s input field. In both cases the file is read in the page and never uploaded.

Credits

These tools come from WhiteboxTools by Prof. John Lindsay, University of Guelph.