{ "culture": "en-US", "name": "SacDelta_Lidar_201712", "guid": "", "catalogPath": "", "snippet": "Digital Elevation Model (DEM) of the Sacramento-San Joaquin Delta derived from LiDAR collected in 2017.", "description": "

Product: This data set is comprised of a mosaic of 0.5-meter bare-earth digital elevation models (DEMs) in ERDAS IMG format. Vertical units are in feet, referenced to NAVD88. <\/SPAN><\/P>

Geographic Extent: Approximately 1,312 square miles across several counties in central California. <\/SPAN><\/P>

Important: This is a replacement of the original image service posted to DWR's public-facing image server from the version posted in 9/2019. The original version was posted incorrectly, namely that it was posted by creating a service from a raster mosaic dataset with the datum defined as plain NAD83, but the source tiles were from files with a stamped datum of NAD83/NSRS 2007. The result was a slight horizontal shift that produces issues with project-on-the-fly capable software. <\/SPAN><\/P>

This service was created using a raster mosaic dataset sourced from tiles that are all stamped as plain NAD83. The tiles were actually restamped from the original USGS deliverable - defined as NAD83/NSRS2007, under guidance from DWR land surveyors about issues when doing so, and whose guidance is to always use the basic NAD83 datum as the stamp. Questions about this may be directed to the supervising land surveyor of DWR's Division of Engineering, Geodetic Branch. As such, this service was republished as above on March 10, 2020, by DWR Division of Engineering. Rest of original service metadata follows (including original NAD83/NSRS2007 references). <\/SPAN><\/P>

Dataset description: The CA Sacramento Delta LiDAR 2017 D16 LiDAR project called for the planning, acquisition, processing, and production of derivative products of LiDAR data to be collected at a nominal pulse spacing (NPS) of 0.35 meters. Project specifications were based on the U.S. Geological Survey National Geospatial Program LiDAR Base Specification, Version 1.2. The data was developed based on a horizontal datum/projection of NAD83 (NSRS2007) UTM Zone 10 (EPSG 3717) meters, and a vertical datum of NAVD88 (GEOID12B), US survey feet. LiDAR data was delivered as processed classified LAS 1.4 files formatted to 1,706 individual 1,500-meter x 1,500-meter tiles. Other LiDAR products include tiled intensity imagery, tiled bare-earth DEMs, and tiled first return DSMs, all tiled to the same tiling schema. This version of the data is referenced to the 2017 epoch, which is different from the USGS version that is referenced to the 2011 epoch. Ground Conditions: LiDAR was collected from December 9, 2017 through January 21, 2018 by Woolpert, while no snow was on the ground and rivers were at or below normal levels. Saturated or partially flooded farm fields were identified following data acquisition. Through technical guidance discussions with USGS and the California Department of Water, it was determined such areas shall not be considered hydrologic features. Intermittently, partially flooded, irregular, and apparently non-agricultural fields were treated as hydrologic features. In all cases, best professional judgement was used in determination of treatment. In order to post process the LiDAR data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Woolpert established 35 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 143 independent accuracy checkpoints (75 NVA points and 68 VVA points), were collected and used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. <\/SPAN><\/P>

This data set was collected and produced by Woolpert for purposes of and under contract to USGS. Data are considered public domain. <\/SPAN><\/P>

DWR makes no warranties or guarantees \u2014 either expressed or implied \u2014 as to the completeness, accuracy, or correctness of the data. DWR neither accepts nor assumes liability arising from or for any incorrect, incomplete, or misleading subject data. <\/SPAN><\/P>

This is an official DWR Image Service, published on March 10, 2020 by Joel Dudas of the Division of Engineering, Geodetic Branch, Geospatial Data Support Section, who may be contacted at joel.dudas@water.ca.gov, or 916-651-7002. <\/SPAN><\/P><\/DIV><\/DIV><\/DIV>", "summary": "Digital Elevation Model (DEM) of the Sacramento-San Joaquin Delta derived from LiDAR collected in 2017.", "title": "SacDeltaLidar_201712", "tags": [ "Sacramento", "San Joaquin", "Delta", "California", "aerial imagery", "orthophotography", "LiDAR", "2017" ], "type": "Image Service", "typeKeywords": [ "Data", "Service", "Image Service", "ArcGIS Server" ], "thumbnail": "thumbnail/thumbnail.JPEG", "url": "https://parcgis.water.ca.gov/arcgisimgpublicmngr/admin/elevation/SacDelta_Lidar_201712/ImageServer", "spatialReference": "NAD_1983_UTM_Zone_10N", "accessInformation": "California DWR, USGS, Woolpert", "licenseInfo": "

public domain<\/SPAN><\/P><\/DIV><\/DIV><\/DIV>", "MinScale": 1.5E8, "MaxScale": 5000.0 }