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Advantages of Light Detection and Ranging (LiDAR) vs. Conventional Elevation Models

highly accurate slope data derived from LiDAR assists in the visualization of slope breaks on the landform. more intense than with traditional methods (NRCS photos -- click to enlarge)
highly accurate slope data derived from LiDAR assists in the visualization of slope breaks on the landform. more intense than with traditional methods (NRCS photos -- click to enlarge)

highly accurate slope data derived from LiDAR assists in the visualization of slope breaks on the landform. more intense than with traditional methods (NRCS photos -- click to enlarge)

LiDAR is the technology of using pulses of laser light striking the surfaces of the earth and measuring the time of pulse return. The LiDAR laser scanner is mounted photogrammetrically in the bottom of an airplane (similar to an aerial camera) along with an inertial measuring unit and airborne GPS.  Robust data storage is required to process the return time for each pulse returned back to the sensor and calculate the variable distances from the sensor, or changes in terrain/land cover surfaces.  As with any photogrammetric GPS activity, the LiDAR system requires a surveyed ground-base location to be established in the project area.  LiDAR scanning can occur day or night, as long as clear flying conditions are present.

On a functional level, LiDAR is typically defined as the integration of three technologies into a single system capable of acquiring data to produce accurate digital elevation models (DEMs).  The technologies are: lasers, the global positioning system (GPS), and inertial navigation systems. Combined, they allow a high degree of accuracy in the positioning of the footprint of a laser beam as it hits an object.  Lasers by themselves have very accurate ranging capabilities.  They can measure distances accurate to a few centimeters.  The accuracy limitations of LiDAR systems are due primarily to the GPS and IMU (inertial measurement unit) components.  Advancements in commercially available GPS and IMU have made it possible to obtain an increasingly high degree of accuracy using LiDAR from moving platforms, such as aircraft.  The higher resolution, more detailed surfaces generated by LiDAR can detect subtle changes in the landscape because the post spacing is more intense than with traditional methods.

“I was amazed at the detail and accuracy available with the LiDAR data. Landform breaks were easily discernable and always matched correctly when checked in the field.  I have used DEMs with 3- meter and 1.5-meter resolution doing update work in Indiana; and while helpful, a complete delineation of the landforms could not be made from these.  I believe this product greatly improves the efficiency of the mapping process and accuracy of the soil survey,” said NRCS soil scientist Justin Bender.  “I am glad to have worked with LiDAR during my detail to Alabama and hope this resource will be available for future soil surveys.”

mage on the left shows 10-foot contours derived from a 10-meter DEM. The image on the right shows 5-foot contours (with soil lines) derived from LiDAR (NRCS photos -- click to enlarge)highly detailed contour lines from the LiDAR delineate elevation and position of landforms on the landscape (NRCS photos -- click to enlarge)

image on the left shows 10-foot contours derived from a 10-meter DEM. The image on the right shows 5-foot contours (with soil lines) derived from LiDAR

highly detailed contour lines from the LiDAR delineate elevation and position of landforms on the landscape (NRCS photos -- click to enlarge)

During pre-mapping, LiDAR allows soil scientists to digitally map visual landform segments with increased accuracy, promote the visualization of landscape patterns, increase accuracy in placement of soil lines and transects, take advantage of the latest technology to reduce the amount/cost of time spent in the field, and map areas that are inaccessible to soil scientists.

 

 

 

 

Key Advantages of LiDAR

 • Increased efficiency • Using LiDAR to create a soil map saves time • Map compilation is completely unnecessary. • Increased accuracy • Soil Scientists use more accurate data to determine placement of soil lines and transects and the process is much less subjective than interpreting stereo photo pairs. • Digitized placement of the soil lines is determined by the original author of the soil map, thereby avoiding the problems of line-shift and symbol errors during map compilation. • Increased knowledge • LiDAR provides a base from which to more easily share ideas, landform traits, and mapping concepts. • Increased accountability • LiDAR promotes the use of onscreen digitizing. When the data is in a geodatabase stored on a central server, the progress and quality of the soil maps are easily checked by the project leader and quality assurance personnel. • Increased technology training • The process fosters on-the-job training in new technology for all project members. • The process integrates well with other technology- driven tools like ArcGIS, GPS Garmin, and TEUI. The highly accurate slope data derived from LiDAR assists in the visualization of slope breaks on the landform.

 

 

 

 

 

 

 

 


Your contacts are NRCS cartographer Joe Gardinski at 256-372-4237 and NRCS soil scientists Eddie Davis at 256-372-4237, Justin Bender at 574-936-2839, and Doug Clendenon at 256-372-5949.