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Light Detection and Ranging (LiDAR)
LiDAR, what is it and why do we need it? Many might ask why it is worthwhile to spend $200 to $300 per square mile to acquire this data. LiDAR technology produces one of, if not the most valuable data sets for remote sensing of the earths surface. The term Lidar stands for Light Detection and Ranging, but in every day language think of it as data collected by bouncing lasers off the earths surface at a high rate of speed creating a very accurate representation of the earths surface very quickly. The National Ecological Observatory Network has developed several short and informative videos on LiDAR and how it works and what it can be used for. Their video "How does LiDAR Remote Sensing Work" is only 8 minutes long but it provides a very clear understandable summary of what it is how it is acquired and what it is used for.
The LiDAR acquired for Maine by the GeoLibrary is specifically georeferenced to locate the data in terms of latitude, longitude and elevation. This data can be used for many purposes including determination of:
- Land use/land cover
- Land cover characterization
- Vegetation classification
- Buildings and structures
- Biomass and carbon/Green House gas calculations
- Transmission and utility maps
- Emergency response plans
- Pre- and post-event/disaster planning
In 2009 the Maine State planning Office, Floodplain Program documented the need for LiDAR data acquisition as part of its Interagency Report On Floodplain Mapping to the 124th Legislature. Thirteen state agencies participated in the development of this report and documented the need for LiDAR data and the benefits it would have to their programs.
Statewide LiDAR Acquisition
The Maine GeoLibrary, with support from the Maine Office of GIS continues to work on acquiring LiDAR for the state of Maine. Since 2009 the GeoLibrary has initiated projects that emphasize collaborative partnerships to maximize the size and cost effectiveness of data acquisition. The first project included all of the coastal states in the Northeast from New York to Maine. So far these efforts have accomplished the acquisition of nearly 10,000 sq. mi. of data with vertical accuracies of +/- 18 cm or better.
The USGS 3D Elevation Program (3DEP) initiative was developed to assist states in collecting high resolution topographic data. This program will provide up to 50% matching funds for projects meeting it's specifications. Larger projects of 5,000 sq. mi. or more can command as much as a 20% discount in acquisition costs. Consequently the GeoLibrary is looking forward to participating in this program and is actively searching for partners to pursue applications for this funding.
Cost Benefit Analysis and Typical Uses of LiDAR Data
LiDAR data provides extensive benefits to numerous diverse economic development interests. The USGS has completed an extensive cost benefit analysis of this program. An analysis of 10 business needs showed a cost benefit of at least 4:1 using the most conservative benefit estimates. A separate analysis fact sheet was completed for each state. A review of the Maine fact sheet shows an annual benefit of $4.73 million annually. This is probably a low estimate considering the fact that data acquisition costs have been falling significantly since the study was first commissioned. The USGS estimate of cost for completing acquisition for the whole state is $10.85 million based on data acquisition costs of over $300/sq. mi. Recent projects have realized a reduction in cost to $252/ sq. mi. and with larger acquisitions of 5,000 sq. mi. or greater we could see competitive pricing of less than $200/ sq. mi.
The Missouri Department of Transportation commissioned a study to evaluate LiDAR technology and its value to MODOT in 2010. The report was completed by the Sanborn Map Company. The report contains an impressive comparative analysis using traditional photogrammetric, mobile LiDAR, Static LiDAR and aerial LiDAR acquisition data sets. The result is a very favorable cost benefit analysis which is enhanced when multiple agencies share the costs of data acquisition.
The North Carolina Department of Transportation completed a research project "Infrastructure Investment Protection with LiDAR". This study provides comprehensive analysis of various methods of LiDAR collection and its cost effective application to various project types. It shows very favorable safety, applicability, data collection productivity, and cost effectiveness fixed terrestrial, Mobile terrestrial, and airborne lidar collection methods. Again the cost effectiveness of this data is greatly improved when the costs of data acquisition are shared.
- Agriculture and Forestry
Adam Birr, PhD. D. of the Minnesota Department of Agriculture completed a research project in cooperation with the University of Minnesota. The project was titled "Identifying Critical Portions of the Landscape for Water Quality Protection Using Terrain Analysis" One of the conclusions of this project was that LiDAR Based GIS surveys could be completed in a matter of hours and a county wide study could be completed in just a few weeks, compared to doing an on the ground walking survey that could take years to complete and require thousands of man hours to duplicate.
Photogrammetric Engineering & Remote Sensing published an interesting article on segmenting trees heights in complex mixed conifer forests on rugged terrain in its January 2012 Vol. 78, No. 1 issue. It was written by Wenkai Li and Winghua Guo are with the Sierra Nevada, Research Institute, School of Engineering, University of California, Merced, CA 95343 (firstname.lastname@example.org).
For more information on the program check out our links below. To find out how your community can participate in the program contact the Maine GeoLibrary Board. You will find a history of LiDAR acquisition projects at this link.