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Learn how to effectively manage and utilize LiDAR-derived information for conservation planning. Explore methods, data formats, and derivative data types to optimize the use of LiDAR data in various applications such as soil mapping, flooding frequency interpretation, and forest delineation.
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Management and Use of LiDAR-Derived Information Elizabeth Cook USDA-NRCS Columbia, MO
Project Deliverables • LAS mass point files, all returns, with and without breaklines, qq quad tiles • 1-m ESRI Grid bare earth DEM files, quad and qq quad tiles • 1-foot pixel natural color digital orthophotos in geotiff, ecw and sid formats (collected with LiDAR and used for breakline mapping) • Independent control points for QA • Misc shapefiles – tile indexes, breaklines
Total for 4-county project area Grid DEMs 31.4 gb LAS 92 gb Imagery 261.2 gb (one format or version of the data) One 7.5-minute quad Grid DEM – 585 mb LAS 1.8 gb Imagery 4.6 gb Data Management – File Sizes
Data Management – Formats, Areas of Coverage, Products • Method 1 – deliver “raw” data, such as LAS, ASCII mass point files or ESRI terrains; users clip to areas of interest and process derivatives • Method 2 – deliver tiles of derivatives according to anticipated users needs • Method 3 – deliver some derivatives, but customize as necessary, and let high-end users process their own
Data Formats – “Raw” • LAS – industry standard binary file of x,y,z,i (and more) data • not many softwares read (changing fast) • may want to generalize, sample per class, etc • ASCII x,y,z • large and slow • ESRI Terrain – multi-resolution database object that “stages” the data for subset, generalization and derivatives • requires knowledgeable users • lots of time to create
Terrain visualized as a TIN; resolution based on scale of display and pyramid levels of terrain
Derivative Data from LiDAR • Digital Elevation Model (bare-earth raster) • Digital Surface Model (with canopy) • Hillshade • TIN – ESRI vs. CAD • Contours All are 2-D representations of terrain
LiDAR data can speed design time by eliminating much of the field survey. • This dam was designed in 15 minutes without ever going to the field.
Extract first return LiDAR points • Low-pass filter to generalize • Polygonize for forest/non-forest layer (red mask)
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