2015 - 2016 LARIAC Lidar DEM: Los Angeles Region, CA

This raster dataset contains LiDAR-derived elevation data flown from Fall 2015 to Spring 2016, with additional reflights through Fall 2016. This dataset encompasses all of the LARIAC4 project, comprised of approximately 4214 square miles.

The NOAA Office for Coastal Management (OCM) downloaded this digital elevation model (DEM) data from the USGS site: ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/OPR/CA_LosAngeles_2016// and processed the data to be available on the Digital Coast Data Access Viewer (DAV).

In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

Breakline data are also available. These data are are available for download at the link provided in the URL section of this metadata record. These products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

The purpose of this dataset is to create a representation of the topology of the study area with all vegetation and man-made structures removed. In addition, this dataset was used for creation and QC of contours and hydro-breaklines, in tandem with the raw LiDAR data.

CONTRACTOR: Pictometry International, Inc.

In no event shall the creators, custodians, or distributors of these data be liable for any damages arising out of its use, or from the inability of the customer to use these data for their intended application.

Any conclusions drawn from the analysis of this information are not the responsibility of Pictometry, LARIAC, USGS, NOAA, the Office for Coastal Management or its partners

Data is available online for bulk and custom downloads.

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.2.1.3497

The same 212 checkpoints that were used to test the vertical accuracy of the lidar, were used to validate the vertical accuracy of the final DEM products as well. Accuracy results may vary between the source lidar and final DEM deliverable. DEMs are created by averaging several lidar points within each pixel which may result in slightly different elevation values at each survey checkpoint when compared to the source LAS, which does not average several lidar points together but may interpolate (linearly) between two or three points to derive an elevation value. The vertical accuracy of the DEM is tested by extracting the elevation of the pixel that contains the x/y coordinates of the checkpoint and comparing these DEM elevations to the surveyed elevations. Dewberry typically uses LP360 software to test the swath lidar vertical accuracy, Terrascan software to test the classified lidar vertical accuracy, and Esri ArcMap to test the DEM vertical accuracy so that three different software programs are used to validate the vertical accuracy for each project.

This DEM dataset was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10 cm (0.33 ft) RMSEz Vertical Accuracy Class. Actual NVA accuracy was found to be RMSEz = 0.31 ft (9.4 cm), equating to +/- 0.60 ft (18.2 cm) at 95% confidence level. Actual VVA accuracy was found to be +/- 0.52 ft (15,8 cm) at the 95th percentile.

LiDAR intensity values were captured at 12-bit levels and scaled down to 8-bit during processing of the intensity raster.

Data cover the entire area specified for this project.