Description: This feature class is a subset of a larger 2014 2ft topographical dataset that was created at SanGIS. This feature class covers the Poway and La Mesa area approximately. The dataset was created by clipping the larger topographical dataset to the Poway La Mesa Grid cell of the SanGIS Topographical Index (GRID_2014_2Ft_Topo_Index layer).The larger topographical dataset was created by merging all of the raw, individual two foot contour tiles provided by Photo Science. The Z and M data provided in the raw, individual tiles was removed to allow the Dissolve tool to be run. The feature class was then Dissolved by Elevation and LType (no multipart features, and "Unsplit lines" selected). The XY Tolerance was set at the default (0.00328083 ft), so some of the line segments that were closer than this tolerance snapped together and created an overhanging line segment. In order to get rid of these very small lines, any remaining individual lines less than 1" (0.08333 ft) were removed from the data.Dataset Description: San Diego, California 2014 LiDAR project called for the Planning, Acquisition, processing and derivative products of LIDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LIDAR Specification, Version 1. The data was developed based on a horizontal projection/datum of NAD83, State Plane California VI, Survey Feet and vertical datum of NAVD1988 (GEOID12A), Survey Feet. LiDAR data was delivered in RAW flight line swath format, processed to create Classified LAS 1.2 Files formatted to 1565 individual 5000 ft x 5000 ft tiles, and corresponding Intensity Images and Bare Earth DEMs tiled to the same 5000 ft x 5000 ft schema, and Breaklines in Esri geodatabase format. Ground Conditions: LiDAR was collected in late 2014 and early 2015, while no snow was on the ground and rivers were at or below normal levels. In order to post process the LiDAR data to meet task order specifications, Photo Science established a total of 88 QA calibration control points and 80 Land Cover control points that were used to calibrate the LIDAR to known ground locations established throughout the San Diego, California project area.Photo Science used classified LAS files to show the manually reviewed bare earth surface. This allowed the user to create Intensity Images, Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 2.5 foot cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, hydro-flattened DEMs as necessary. This resulting data was used to create the raw, individual two foot contour tiles.
Service Item Id: 9d0dff66781d419085d4b19e57ab7857
Copyright Text: SanGIS, Photo Science, A Quantum Spatial Company flew the LiDAR and processed the data.