Disposal Area Laser Scanning
USACE, Jacksonville District
Arc Surveying & Mapping, Inc. has over 20 years of topographic and hydrographic surveying experience. As a technology oriented company, Arc is continually experimenting with modern equipment, testing new technology against previous conventional survey methods in order to provide clients with more and better data at a reduced cost. During 2011, Arc began testing laser scanning of lightly vegetated areas to determine if a reliable ground surface could be determined.
In the case of the Buck Island Dredge Disposal area in Jacksonville, Florida, Arc laser scanned the entire site in four days. The previous conventional survey using RTK/GPS data cross-sectioning at 100 ft stationing required 14 days using two GPS equipped crews.
The time and cost savings between a two-person laser scanning crew versus two, two-person GPS crews was tremendous, a cost savings of more than 50% – and the laser scan data covered 100% of the disposal area. Obviously vegetative areas would normally be an issue with laser scan data as the scanner doesn’t know the difference between the ground surface and vegetation. However, the Riegl VZ400 laser scanner used for this survey provided separate data returns which allowed Arc to remove the vegetation from the survey. (Note the yellow vegetative return in the above image). With careful editing of each scan, vegetation can be removed. As a result, Arc was able to provide 100% coverage of the entire disposal area and a more precise quantity of the area capacity. Also note that the lower left image is not a photograph, it is laser scan data. This experiment was performed at Arc’s expense and given to the Jacksonville District for future consideration of laser scanning versus conventional surveying methods.