| Aerial imagery from UAS survey |
Structure from Motion - UAS |
This portion of the data release presents the raw aerial imagery collected during the Unmanned Aerial System (UAS) survey of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta on 2018-10-23. The imagery was acquired using two Department of Interior owned 3DR Solo quadcopters fitted with Ricoh GR II digital cameras featuring global shutters. The cameras were mounted using a fixed mount on the bottom of the UAS and oriented in a roughly nadir orientation. The UAS were flown on pre-programmed autonomous flight lines at an approximate altitude of 120 meters above-ground-level, resulting in a nominal ground-sample-distance (GSD) of 3.2 centimeters per-pixel. The flight lines were oriented roughly east-west and were spaced to provide approximately 66 percent overlap between images from adjacent lines. The cameras were triggered at 1 Hz using a built in intervalometer. After acquisition, the images were renamed to include flight number and acquisition time in the file name. The coordinates of the approximate image acquisition location were added ('geotagged') to the image metadata (EXIF) using the telemetry log from the UAS onboard single-frequency autonomous GPS. The image EXIF were also updated to include additional information related to the acquisition. Although the images were recorded in both JPG and camera raw (Adobe DNG) formats, only the JPG images are provided in this data release. The data release includes a total of 3,567 JPG images. Images from takeoff and landing sequences were not used for processing, and have been omitted from the data release. The images from each flight are provided in a zip file named with the flight number. |
Joshua Logan |
| Digital surface model (DSM) |
Structure from Motion - UAS |
This portion of the data release presents a digital surface model (DSM) and hillshade of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta. The DSM has a resolution of 10 centimeters per-pixel and was derived from structure-from-motion (SfM) processing of aerial imagery collected with an Unmanned Aerial System (UAS) on 2018-10-23. Unlike a digital elevation model (DEM), the DSM represents the elevation of the highest object within the bounds of a cell. |
Joshua Logan |
| Ground control point locations for UAS survey |
Structure from Motion - UAS |
This portion of the data release presents the locations of the temporary ground control points (GCPs) used for the structure-from-motion (SfM) processing of the imagery collected during the Unmanned Aerial System (UAS) survey on of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta on 2018-10-23. The GCPs were used to establish ground control for the survey and consisted of 24 small (80 x 80 centimeter) square tarps with black-and-white cross patterns placed on the ground surface throughout the mapping area during the survey. The GCP positions were measured using RTK GPS, with corrections from a GPS base station located approximately 3 kilometers south of the study area. The GCP positions are presented in a comma-delimited text file. |
Joshua Logan |
| Orthomosaic imagery |
Structure from Motion - UAS |
This portion of the data release presents a high-resolution orthomosaic image of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta. The orthomosaic has a resolution of 3 centimeters per-pixel and was derived from structure-from-motion (SfM) processing of aerial imagery collected with an Unmanned Aerial System (UAS) on 2018-10-23. The raw imagery used to create the orthomosaic image was acquired using two UAS fitted with Ricoh GR II digital cameras with global shutters. The UAS were flown on pre-programmed autonomous flight lines at an approximate altitude of 120 meters above-ground-level. The flight lines were oriented roughly east-west and were spaced to provide approximately 66 percent overlap between images from adjacent lines. The cameras were triggered at 1 Hz using a built-in intervalometer. The imagery was geotagged using positions from the UAS onboard single-frequency autonomous GPS. Ground control was established using twenty-four ground control points (GCPs) consisting of small square tarps with black-and-white cross patterns distributed throughout the mapping area. The GCP positions were measured using RTK GPS, with real-time corrections from a GPS base station located approximately 3 kilometers south of the study area. The orthomosaic imagery is provided at a resolution of 3 centimeters per-pixel, in a three-band RGB cloud-optimized GeoTIFF format, with 8-bit unsigned integer values compressed using high-quality JPEG compression. |
Joshua Logan |
| Topographic point cloud |
Structure from Motion - UAS |
This portion of the data release presents a topographic point cloud of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta, derived from structure-from-motion (SfM) processing of aerial imagery collected with an Unmanned Aerial System (UAS) on 2018-10-23. The point cloud contains 380,296,568 points at an approximate point density of 323 point per square-meter. Each point contains an explicit horizontal and vertical coordinate, color, intensity, and classification. The point cloud is tiled into 500 x 500-meter tiles to reduce file size. The raw imagery used to create this point cloud was acquired using two UAS fitted with Ricoh GR II digital cameras global shutters. The UAS were flown on pre-programmed autonomous flight lines at an approximate altitude of 120 meters above-ground-level. The flight lines were oriented roughly east-west and were spaced to provide approximately 66 percent overlap between images from adjacent lines. The cameras were triggered at 1 Hz using a built-in intervalometer. The imagery was geotagged using positions from the UAS onboard single-frequency autonomous GPS. Ground control was established using twenty-four ground control points (GCPs) consisting of small square tarps with black-and-white cross patterns distributed throughout the mapping area. The GCP positions were measured using RTK GPS, with real-time corrections from a GPS base station located approximately 3 kilometers south of the study area. |
Joshua Logan |
