Working with LiDAR

What is LiDAR? | What are LiDAR file formats? | Where can I find LiDAR data?I want to use LiDAR in Rhino or RevIt | How can I view/clip/convert LiDAR data?


What is LiDAR?

LiDAR (Light Detection and Ranging) is a type of remote sensing. It works like radar except it uses light or laser beams instead of radio waves. The time it takes for the laser to travel from the sensor (often mounted on a plane or helicopter) to the surface and back is used to calculate the distance to an object. Those pulses can penetrate non-solid surfaces (e.g.: forest canopy) and the resulting data appears as a point cloud.

LiDAR can be used to provide highly accurate elevation data. The data is collected as points with x, y & z values and these points can be used to create digital elevation models often in GeoTIF/TIFF format. LiDAR data is often in LAS format and may also be in overlapping ground and non-ground files, with the non-ground file showing surface features such as buildings, bridges, and trees.

For an overview of LiDAR technology try this 7-minute video. For more in-depth information, NOAA's Introduction to Lidar self-guided online training is very well done.

What are LiDAR file formats?

For an overview of different LiDAR formats, see our LiDAR Formats help guide.

Where can I find LiDAR data?

We keep lists of LiDAR data sources for Ottawa, Ontario, Canada, and beyond on our LiDAR data page. You may also find our "How to search for GIS data" help guide useful. If you still can't find what you're looking for, let us know at gis@carleton.ca and we'll help.

I want to use this file in Rhino or Revit

Unfortunately none of the GIS softwares on the library's GIS workstations export directly to Rhino (3DM) or Revit formats. However, exporting to DGN will work in Revit and DXF should work in Rhino (if not, please let us know!). Follow the workflow below to export to either format.

How can I view/clip/convert a LiDAR file?

While our LiDAR Formats help guide gives an overview of viewing and exporting LiDAR formats .las, .las, .laz, and .e57 in multiple softwares, if you want to have a look at a LiDAR dataset and clip it or convert it to a different format this workflow in Global Mapper is what we recommend.

  1. If your LiDAR file is in a .zip or .rar file (compressed file), uncompress it.

  2. Open Global Mapper, which is available on the GIS workstations in the library.

  3. Navigate to File > Open Data File(s)... Browse to and select the .las files you want to view. Click Open.

  4. The projection of the dataset should be detected and loaded in the Select Projection dialog box. Click OK. If you are loading multiple LAS files with the same projection, select the Use Selected Projection for All Selected Files checkbox at the bottom of the dialog box. 

  5. The Lidar Load Options dialog box has multiple parameters. In this case, the defaults were selected (Create Point Cloud, all Lidar point classifications and return types selected). Click OK.

  6. The LAS files will load. To view them in 3D, navigate to View > 3D View... 

  7. To export all or part of a LiDAR dataset, click File > Export > Export Vector/Lidar Format

  8. Select your export format, such as DGN, Lidar LAS File, E57, or other compatible vector format. (You will get an error if you select a format that is not compatible with point clouds.)

  9. Click the Export Bounds tab, then Draw a Box... if you only want part of the dataset you have loaded. Otherwise the entire dataset will export. Click OK.

  10. Browse to where you want to save your file and name it something helpful (e.g.: RideauCanal.dgn), then Save.

Content last reviewed: September 13, 2018