2021 - 2022 UCSD/USGS Lidar DEM: Sierra Nevada, CA

Original Dataset Product: Hydro-flattened 0.5 m Digital Elevation Model (DEM) data covering the CA Sierra Nevada project area.

Original Dataset Geographic Extent:

CA_SierraNevada_1_2022 (Work Unit 300057) - This dataset and derived products encompass an area covering approximately 1204 square miles in the northern region of the project.

CA_SierraNevada_2_2022 (Work Unit 300058) - This dataset and derived products encompass an area covering approximately 1687 square miles in the northern region of the project.

CA_SierraNevada_3_2022 (Work Unit 300059) - This dataset and derived products encompass an area covering approximately 1353 square miles in the northern region of the project.

CA_SierraNevada_4_2022 (Work Unit 300244) - This dataset and derived products encompass an area covering approximately 2688 square miles in the northern region of the project.

CA_SierraNevada_5_2022 (Work Unit 300245) - This dataset and derived products encompass an area covering approximately 2298 square miles in the central region of the project.

CA_SierraNevada_6_2022 (Work Unit 300246) - This dataset and derived products encompass an area covering approximately 2136 square miles in the northern region of the project.

CA_SierraNevada_7_2022 (Work Unit 300271) - This dataset and derived products encompass an area covering approximately 1193 square miles in the northern region of the project.

CA_SierraNevada_8_2022 (Work Unit 300363) - This dataset and derived products encompass an area covering approximately 2167 square miles in the central region of the project.

This area includes the Sierra Nevada Mountains from the eastern shore of Lake Tahoe west to the ridgeline of the Carson Range, most of the city of South Lake Tahoe and traverses due south to the unincorporated community of Strawberry, then follows the mountain ridge between Tuolumne and Mono counties. It includes the community of Bridgeport and spans east-northeast to the Nevada border.

CA_SierraNevada_9_2022 (Work Unit 300364) - This dataset and derived products encompass an area covering approximately 2944 square miles in the southern region of the project.

CA_SierraNevada_10_2022 (Work Unit 300365) - This dataset and derived products encompass an area covering approximately 2593 square miles in the southern region of the project.

CA_SierraNevada_11_2022 (Work Unit 300459) - This dataset and derived products encompass an area covering approximately 1771 square miles in the central region of the project.

CA_SierraNevada_12_2022 (Work Unit 300460) - This dataset and derived products encompass an area covering approximately 1410 square miles in the central region of the project.

CA_SierraNevada_13_2022 (Work Unit 300461) - This dataset and derived products encompass an area covering approximately 3094 square miles in the central region of the project.

CA_SierraNevada_14_2022 (Work Unit 300462) - This dataset and derived products encompass an area covering approximately 3866 square miles in the southern region of the project.

Original Dataset Description: Lidar flight line swaths were processed to create classified LAS 1.4 files delineated in 1,000m x 1,000m tiles. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create 0.5 meter hydro-flattened Raster DEMs delineated in 1,000m x 1,000m tiles. Additional products include classified LAS files, intensity images, highest hit surface models, and 3D breaklines of rivers and lakes within the study area.

Original Dataset Ground Conditions: Acquisition occurred free of smoke, fog and cloud cover.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the GeoTIFF files hosted by USGS on Amazon Web Services.

The purpose of the lidar data was to produce a high accuracy 3D dataset that meets all necessary standards laid out by the 3D Elevation Program. The Natural Resources Conservation Service (NRCS), and the University of California San Diego (UCSD) were partners. The lidar point cloud data were used to create classified lidar LAS files, intensity images, hydro-flattened DEMs, highest hit surface models, and 3D breaklines of rivers and lakes within the study area. Data were collected to aid UCSD & USGS in assessing the topographic and geophysical properties of the study area to support fire mitigation and natural disaster mitigation mapping.

USGS Contract No. 140G0221D0012

Raster File Type = TIFF

Bit Depth/Pixel Type = 32-bit float

Raster Cell Size = 0.5 meter

Interpolation or Resampling Technique = Triangulated Irregular Network

Required Vertical Accuracy = 19.6 cm NVA

Any conclusions drawn from the analysis of this information are not the responsibility of 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.

Lidar horizontal accuracy is a function of Global Navigation Satellite System (GNSS) derived positional error, flying altitude, and INS derived attitude error. The obtained RMSEr value is multiplied by a conversion factor of 1.7308 to yield the horizontal component of the National Standards for Spatial Data Accuracy (NSSDA) reporting standard where a theoretical point will fall within the obtained radius 95 percent of the time.

Based on a flying altitude of 2,500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.019 meters, these blocks were produced to meet 0.27 meters horizontal accuracy at the 95% confidence level or 16 cm RMSEr.

CA_SierraNevada_1_2022 (Work Unit 300057)

CA_SierraNevada_2_2022 (Work Unit 300058)

CA_SierraNevada_3_2022 (Work Unit 300059)

CA_SierraNevada_4_2022 (Work Unit 300244)

CA_SierraNevada_5_2022 (Work Unit 300245)

CA_SierraNevada_6_2022 (Work Unit 300246)

CA_SierraNevada_7_2022 (Work Unit 300271)

CA_SierraNevada_8_2022 (Work Unit 300363) - Based on a flying altitude of 2,500 meters, an IMU error of 0.003 decimal degrees, and a GNSS positional error of 0.023 meters, this project was produced to meet 0.410 meters horizontal accuracy at the 95% confidence level or 23.5 cm RMSEr.

CA_SierraNevada_9_2022 (Work Unit 300364) - This data set was produced to meet +/- 0.509 m at the 95% confidence level or 29 cm RMSEr.

CA_SierraNevada_10_2022 (Work Unit 300365) - This data set was produced to meet +/- 0.509 m at a 95% confidence level or 29 cm RMSEr.

CA_SierraNevada_11_2022 (Work Unit 300459) - Based on a flying altitude of 2,500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.027 meters, this project was produced to meet 0.274 meters horizontal accuracy at the 95% confidence level or 15.8 cm RMSEr.

CA_SierraNevada_12_2022 (Work Unit 300460) - Based on a flying altitude of 2,500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.023 meters, this project was produced to meet 0.273 meters horizontal accuracy at the 95% confidence level or 15.8 cm RMSEr.

CA_SierraNevada_13_2022 (Work Unit 300461) - Based on a flying altitude of 2,500 meters, an IMU error of 0.003 decimal degrees, and a GNSS positional error of 0.023 meters, this project was produced to meet 0.407 meters horizontal accuracy at the 95% confidence level or 23.5 cm RMSEr.

CA_SierraNevada_14_2022 (Work Unit 300462) - . Based on a flying altitude of 2,500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.023 meters, this project was produced to meet 0.273 meters horizontal accuracy at the 95% confidence level or 15.8 cm RMSEr.

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class. The specifications require that classified Non-vegetated Vertical Accuracy (NVA) be computed from the derived DEMs.

USGS DEM Determined Vertical Accuracy:

Non-Vegetated Vertical Accuracy (NVA) = 5.04 cm RMSE

Vegetated Vertical Accuracy (VVA) = 24.69 cm at 95th Percentile

A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

DEM files were tested by NV5 for vertical accuracy. All data is seamless from one tile to the next, no gaps or no data areas.

Data is backed up to cloud storage.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS GeoTIFF files that are hosted on Amazon Web Services (AWS), into the Digital Coast Data Access Viewer (DAV). The DAV accesses the raster data as it resides on AWS.