Getting to Know LiDAR

I’ve worked with a lot of different types of geospatial data in my years at ITT VIS, but one type that I’ve had relatively little experience with is LiDAR. So, when ITT VIS announced that we would be releasing a new LiDAR application, E3De, I figured it was time to come up to speed. Here are a few things I’ve learned and helpful resources I’ve found, along the way:

What is LiDAR?

LiDAR = Light Detection and Ranging. In a nutshell, a LiDAR sensor measures distances by sending out and recording the return of laser pulses. A LiDAR system collects 3D data in the form of a point cloud. Here are some of the advantages of LiDAR:

• Can be collected day or night.
• Has relatively high accuracy (around 10 to 50 cm vertically and horizontally for airborne LiDAR).
• Can penetrate through some features, such as trees.
• Is less expensive and faster than classic photogrammetry.

What do you use LiDAR for?

LiDAR is used for many applications in many fields:

Field	Example Application
Agriculture	Estimate sun exposure of fieldsDetermine where to apply fertilizer
Archaeology	Plan field campaignsFind features in microtopography revealed below vegetation Find broad features invisible from ground
Biology and Conservation	Derive canopy height, biomass, leaf area index
Recreation	Derive orienteering maps
Transportation	Route planning
Geology	Find subtle geomorphic features, like fault scarpsMeasure uplift, erosion
Defense and Intelligence	Determine height of features warfighters will encounterFind features such as tanks Detect aerosol clouds of biological or chemical agents at a distance
Hydrology	Surface hydrology modeling
Urban	Line of sight analyses3D models of urban areas Finding buildings
Hazards Detection, Mitigation	Hazard mapping (fire, flood, landslide)
Film	Create CG environments

LiDAR for geospatial work is usually mounted on an airborne platform and pointed toward the ground. But it can also be non-airborne and pointed in any direction. For example, it can be used for meteorological and astronomical applications, and to help robots avoid obstacles. Some police speed guns use LiDAR. The band Radiohead even made their “House of Cards” video using LiDAR to model environments and people.

How do you get LiDAR data?

Many LiDAR users hire a commercial company to fly a LiDAR system over their area of interest. You can also download previously collected LiDAR datasets:

• CLICK (USGS): US point cloud data collected by the USGS.
• NOAA’s State Projects: US Coastal Lidar data, including topographic and bathymetric, from different US government entities.
• OpenTopography: LiDAR, from earth science related research projects. They also provide LiDAR training courses, a blog and a forum.
• LiDAR Data Portal: Tons of LiDAR data for locations around the world.
• NCALM LiDAR Data Distribution Center: US LiDAR DEM data for National Science Foundation funded research projects.

Where can you learn more?

• There will be an International LiDAR Mapping Forum in Denver, January 23-25, 2012, including intro to LiDAR workshops (look for me there). Check the LiDAR Resources section of this site for LiDAR system operators around the world.
• The USGS Center for LiDAR Information Coordinate and Knowledge (CLICK) site has forums discussing a wide variety of LiDAR related topics.
• NOAA has an excellent Introduction to LiDAR online training. It is designed for those working on coastal applications, but is full of great general LiDAR lessons.

What are the LiDAR resources you turn to most?

And, which features of LiDAR do you find most useful?