The Colorado Geological Survey is actively involved in the acquisition of LiDAR data within Colorado. We are cooperating with other state and federal agencies and private industry with the ultimate goal of completing a LiDAR survey of the entire state.
What is LiDAR?
LiDAR stands for light detection and ranging. This state-of-the art technology relies on the projection of millions of short laser pulses to the ground from a specially equipped aircraft. The result is extremely detailed ground elevation data. The data from these LiDAR reflections are collected by measuring the time it takes for the aircraft to receive each of the millions of laser reflections. The resulting data is then combined and converted into an elevation image that looks exactly like the terrain below the aircraft, including buildings, trees, roadways, creeks, and rock outcrops. Also, using powerful software the “raw” LiDAR data can be processed to generate a number of useful end products, including an accurate “bare-earth” terrain model where trees, vegetation, and man-made structures have been edited out.
How does it work?
LiDAR systems vary by manufacturer, but all use the following instrumentation: a laser source and detector; a scanning mechanism and controller; airborne GPS and IMU equipment; a high-accuracy, high-resolution clock for timing laser emissions, reflections, GPS/IMU, and scan-angle measurements; high performance computers; and high capacity data recorders. With these components, LiDAR data collection is possible:
- A pulse of laser light is emitted and the precise time is recorded
- The reflection of that pulse from the surface is detected and the precise time is recorded
- Using the constant speed of light, the time difference between the emission and the reflection can be converted into a slant range distance (line-of-sight distance)
- With the very accurate position and orientation of the sensor provided by the airborne GPS and inertial measurement unit (IMU) data, the XYZ coordinate of the reflective surface can be calculated
How is the data used?
LiDAR offers many advantages over traditional photogrammetric methods for collecting elevation data. These include high vertical accuracy, fast data collection and processing, robust data sets with many possible products, and the ability to collect data in a wide range of conditions.
Because of LiDAR’s ability to penetrate vegetation, the data is used to map unknown young faults, more accurately locate previously mapped faults, and determine the potential for geothermal energy in these faulted areas. The data are also used for creating highly detailed maps of other geologic hazards, such as landslides, debris flows, rockfall, and areas prone to flooding. The maps generated are used by local governments for community planning as well as by emergency management agencies. Our geologic mapping program also relies on LiDAR data to precisely map the extent of bedrock units and surficial deposits that cannot be seen in vegetated areas.
LiDAR Map and Data Servers
- Northern Arkansas River Valley Hillshaded DEM (JAVA Viewer or ArcGIS.com MapViewer)
- San Luis Valley Hillshaded DEM (JAVA Viewer or ArcGIS.com MapViewer)
- USGS National Map has downloadable data from the 3DEP Program
- Colorado GeoData Cache has downloadable LiDAR data for Colorado
- OpenTopography.org map viewer of NSF-specific LiDAR data for Colorado
- OpenTopography.org map viewer of non-NSF LiDAR data for Colorado
- NRCS Geospatial Data Gateway
How to obtain LiDAR data for use
The CGS has a database of LiDAR coverage in Colorado that is publicly available, but the CGS is a repository only for data labeled “CGS” on the map above. Contact the other listed entities for access to their data.