LIDAR. The LIDAR data for this project was collected by Watershed Sciences Inc. (now called Quantum Spatial) for Xxxxxx County, Washington. The dataset was made publicly available through the Puget Sound LIDAR Consortium (PSLC). Data was acquired between October 2010 and September 2011, and was processed and provided to Xxxxxx County in 21 separate deliveries. The total acquisition covered 933,000 acres. The data was collected using Xxxxx XXX00 Xxxxx XX xxx Xxxxx XXX00 lasers collecting at rates between 83,000 kHz and 105,900 kHz and flying heights between 900 and 1300 meters. The contract specified a native pulse density of 8 or more pulses per square meter. Watershed Sciences (now Quantum Spatial) provided processed point data files in LAS 1.2 format, and digital elevation model (DEM) ground surface files in ERDAS Imagine IMG format. Data and full documentation are available on the PSLC website: xxxx://xxxxxxxxxxXxXXX.xxx.xxxxxxxxxx.xxx/
LIDAR. At a regional scale, defined as a large network of geotechnical assets, such as a right-of-way through mountains, only mobile LiDAR is an efficient remote sensing tool. Static terrestrial LiDAR, while superior in data density and accuracy to mobile LiDAR, is difficult and expensive to collect for areas larger than specific sites. Mobile LiDAR includes systems mounted on aircraft (airborne) and trucks (terrestrial). Both the terrestrial and airborne mobile systems require precise synchronization and calibration with the GNSS and INS systems. Calibration requires averaging out the cumulative orientation and positioning error caused by INS drift, which increases with longer periods of data collection. Another aspect of calibration with both platforms is the need for horizontal control of the LiDAR point cloud and the final registration of the point cloud in a precise vertical coordinate system using an ellipsoid datum. When regional LiDAR is collected for updating flood plain maps, a much more accurate vertical datum is a requirement. When the most accurate vertical measurements are needed, for hydrologic and hydraulic models, an even more accurate geoid datum is necessary to understand the effect of the earth’s gravity on vertical measurements in order to model the movement of water. Both airborne and terrestrial mobile systems are also characterized by less-dense data than the static terrestrial systems collected at smaller study sites. Lidar “postings” which are the samples recorded from an aircraft can be on the order of 1.8 meters (five foot) among the ground measurements. With terrestrial vehicles, the postings can be much denser, say 10 centimeters among the samples. Regional LiDAR data postings of 1 – 2 meters enable broad-scale and long- term studies of slope stability and other geotechnical hazards such as faults and sink holes. The mobile terrestrial scans allow the inventory of geotechnical assets such as guard rails, retaining walls, and other “street furniture” found along a transportation corridor. While the collection of airborne and terrestrial mobile LiDAR are cost effective for regional collects, repeated data collection over time is less common. This is because regional LiDAR data collection is usually for mission specific purposes such as a proposed road alignment or flood plain mapping. These infrequent data collect limit the application of this type of LiDAR to opportunistic geotechnical studies focused on change detection. Another limi...
LIDAR. Light Detection and Ranging is an optical remote sensing technology that can measure the distance to, or other properties of a target. M Map - A two-dimensional visual portrayal of geospatial data. A map is not the data itself. Metadata – refers to data about data and is used in two fundamentally different concepts • Structured Metadata – design and specification of data structures • Descriptive Metadata –describes a resource for purposes Micro tasking – is the process of breaking a large project into tiny, well defined tasks. The resulting micro tasks can be performed independently, cannot be automated and can be done in a short period of time i.e. less than an hour. Meteorology - is the interdisciplinary scientific study of the atmosphere.
