Orthomosaic imagery of the Los Padres Reservoir delta, Carmel River valley, CA, 2017-11-01

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Frequently anticipated questions:

What does this data set describe?

Title:
Orthomosaic imagery of the Los Padres Reservoir delta, Carmel River valley, CA, 2017-11-01
Abstract:
This portion of the data release presents a high-resolution orthomosaic image of the exposed Los Padres Reservoir delta where the Carmel River enters the reservoir. The orthomosaic has a resolution of 2.5 centimeters per pixel and was derived from structure-from-motion (SfM) processing of aerial imagery collected with an unoccupied aerial system (UAS) on 2017-11-01. The raw imagery used to create the orthomosaic was acquired using a UAS fitted with a Ricoh GR II digital camera featuring a global shutter. The UAS was flown on pre-programmed autonomous flight lines spaced to provide approximately 70 percent overlap between images from adjacent lines. The camera was triggered at 1 Hz using a built-in intervalometer. The UAS was flown at an approximate altitude of 100 meters above ground level (AGL), resulting in a nominal ground-sample-distance (GSD) of 2.6 centimeters per pixel. The raw imagery was geotagged using positions from the UAS onboard single-frequency autonomous GPS. Twenty temporary ground control points (GCPs) consisting of small square tarps with black-and-white cross patterns were distributed throughout the area to establish survey control. The GCP positions were measured using real-time kinematic (RTK) GPS, using corrections from a GPS base station located on a benchmark designated SFML, located approximately 1 kilometer from the study area. The orthomosaic image is provided in a three-band RGB format, with 8-bit unsigned integer values compressed using high-quality JPEG compression. The image has been formatted as a cloud optimized GeoTIFF with internal overviews and masks to facilitate cloud-based queries and display.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-635-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Logan, Joshua B., and East, Amy E., 20230111, Orthomosaic imagery of the Los Padres Reservoir delta, Carmel River valley, CA, 2017-11-01: data release DOI:10.5066/P9J9CHOH, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Logan, Joshua B., and East, Amy E., 2023, Aerial imagery and structure-from-motion data products from a UAS survey of the Los Padres Reservoir delta, Carmel River valley, CA, 2017-11-01: data release DOI:10.5066/P9J9CHOH, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.66731
    East_Bounding_Coordinate: -121.66118
    North_Bounding_Coordinate: 36.38117
    South_Bounding_Coordinate: 36.37326
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5ef5226682ced62aaae6a011?name=LosPadresReservoir_2017-11-01_orthomosaic_25mm_browse.jpg&allow=openTrue (JPEG)
    Orthomosaic image from UAS survey of Los Padres Reservoir.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 01-Nov-2017
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: GeoTIFF
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.025
      Ordinates (y-coordinates) are specified to the nearest 0.025
      Planar coordinates are specified in meters
      The horizontal datum used is NAD83 (National Spatial Reference System 2011) (EPSG:1116).
      The ellipsoid used is GRS 1980 (EPSG:7019).
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    GeoTIFF
    GeoTIFF containing RGB color bands. (Source: Producer defined)
    Band_1
    Red band (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:255
    Band_2
    Green band (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:255
    Band_3
    Blue band (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:255

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Joshua B. Logan
    • Amy E. East
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These data are intended to be used to characterize the position, elevation, volume, and morphology of the Los Padres Reservoir delta sediment where the Carmel River enters the reservoir. This assessment of reservoir sediment was made in response to the 2016 Soberanes Fire in the upper Carmel watershed, followed by high flows during water year 2017.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 01-Nov-2017 (process 1 of 5)
    Aerial imagery was collected using a Department of Interior-owned 3DR Solo quadcopter fitted with a Ricoh GR II digital camera featuring a global shutter. The camera was mounted using a fixed mount on the bottom of the UAS and oriented in an approximately nadir orientation. During image acquisition the UAS was flown on pre-programmed autonomous flight lines at an approximate altitude of 100 meters above ground level (AGL), resulting in a nominal ground-sample-distance (GSD) of 2.6 centimeters per pixel. The flight lines were spaced to provide approximately 70 percent overlap between images from adjacent lines. The camera was triggered at 1 Hz using a built-in intervalometer and was programmed to acquire imagery in JPG format. Before each flight, the camera digital ISO, aperture and shutter speed were manually set to adjust for ambient light conditions. Although these settings were changed between flights, they were not permitted to change during a flight; thus, the images from each flight were acquired with consistent camera settings. Person who carried out this activity:
    Joshua Logan
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    2885 Mission Street
    Santa Cruz, CA
    US

    831-460-7519 (voice)
    831-427-4748 (FAX)
    jlogan@usgs.gov
    Date: 01-Nov-2017 (process 2 of 5)
    Ground control was established using ground control points (GCPs) consisting of small square tarps with black-and-white cross patterns placed on the ground surface throughout the survey area. The GCP positions were measured using survey-grade GPS receivers operating in real-time kinematic (RTK) mode. For each GCP measurement the GPS receiver was placed on a fixed-height tripod and set to occupy each GCP for a minimum occupation time of one minute. The RTK corrections were referenced to a GPS base station occupying a previously established benchmark designated SFML, located on the Los Padres Reservoir dam approximately 1 kilometer from the survey area. In order to ensure consistency with historic surveys, the previously established position for SFML published in Smith and others, 2009 was used for the real-time surveys. After the survey, the static occupation on SFML was submitted to the National Geodetic Survey (NGS) Online Positioning User Service (OPUS). Person who carried out this activity:
    Joshua Logan
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

    831-460-7519 (voice)
    jlogan@usgs.gov
    Date: 2022 (process 3 of 5)
    The image files were renamed using a custom python script. The file names were formed using the following pattern Fx-YYYYMMDDThhmmssZ_Ryz.*, where: - Fx = Flight number - YYYYMMDDThhmmssZ = date and time in the ISO 8601 standard, where 'T' separates the date from the time, and 'Z' denotes UTC ('Zulu') time. - Ry = RA or RB to distinguish camera 'RicohA' from 'RicohB' - z = original image name assigned by camera during acquisition - * = file extension (JPG or DNG)
    The approximate image acquisition coordinates were added to the image metadata (EXIF) ('geotagged') using the image timestamp and the telemetry logs from the UAS onboard single-frequency 1-Hz autonomous GPS. The geotagging process was done using the Geosetter software package. To improve timestamp accuracy, the image acquisition times were adjusted to true ('corrected') UTC time by comparing the image timestamps with several images taken of a smartphone app ('Emerald Time') showing accurate time from Network Time Protocol (NTP) servers. For this survey, +00:00:01 (1 second) was added to the image timestamp to synchronize with corrected UTC time. The positions stored in the EXIF are in geographic coordinates referenced to the WGS84(G1150) coordinate reference system (EPSG:4979), with elevation in meters relative to the WGS84 ellipsoid.
    Additional information was added to the EXIF using the command-line 'exiftool' software with the following command: exiftool ^ -P ^ -IPTC:Credit="U.S. Geological Survey" ^ -IPTC:Contact="pcmsc_data@usgs.gov" ^ -EXIF:Copyright="Public Domain" ^ -XMP:UsageTerms="Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty." ^ -EXIF:ImageDescription="Low-altitude aerial image of the Los Padres Reservoir delta area, Carmel River valley, California, USA, from USGS field activity 2017-635-FA; https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-635-FA" ^ -XMP:Event="Unoccupied Aircraft System survey of Los Padres Reservoir delta area during USGS field activity 2017-635-FA." ^ -EXIF:GPSAreaInformation="Position from UAS onboard autonomous single-frequency GNSS." ^ -EXIF:GPSMapDatum="EPSG:4979 (WGS 84)" ^ -EXIF:Artist="U.S. Geological Survey, Pacific Coastal and Marine Science Center" ^ -IPTC:CopyrightNotice="Public Domain. Please credit U.S. Geological Survey." ^ -IPTC:Caption-Abstract="Aerial image of the Los Padres Reservoir delta area and Carmel River, Carmel River valley, California, USA, from an Unoccupied Aircraft System (UAS) during USGS field activity 2017-635-FA." ^ -sep ", " ^ -keywords="Carmel River, Los Padres Reservoir, Monterey County, California, 2017-635-FA, Unoccupied Aircraft System, UAS, drone, aerial imagery, U.S. Geological Survey, USGS, Pacific Coastal and Marine Science Center" ^ -comment="Aerial image of the Los Padres Reservoir delta area and Carmel River, Carmel River valley, California, USA, from an Unoccupied Aircraft System (UAS) during USGS field activity 2017-635-FA."^ -Orientation= ^ -XMP:AttributionURL="https://doi.org/10.5066/P9J9CHOH" ^ -OffsetTime*=+00:00 -AllDates+=7 ^ -r f* ^ -ext DNG ^ -ext JPG
    Additional metadata tags were populated in the imagery metadata using the following command: exiftool ^ -P ^ "-XMP-photoshop:Credit<IPTC:Credit" ^ "-XMP-iptcCore:CreatorWorkEmail<IPTC:Contact" ^ "-XMP-dc:Rights<EXIF:Copyright" ^ "-XMP-dc:Description<EXIF:ImageDescription" ^ "-XMP-exif:all<GPS:all" ^ "-XMP-exif:GPSLatitude<Composite:GPSLatitude" ^ "-XMP-exif:GPSLongitude<Composite:GPSLongitude" ^ "-XMP-exif:GPSDateTime<Composite:GPSDateTime" ^ "-XMP-photoshop:DateCreated<EXIF:DateTimeOriginal" ^ "-XMP-xmp:ModifyDate<EXIF:ModifyDate" ^ "-XMP-dc:Creator<EXIF:Artist" ^ "-XMP-tiff:Make<EXIF:Make" ^ "-XMP-tiff:Model<EXIF:Model" ^ -overwrite_original ^ -ext JPG Person who carried out this activity:
    Joshua Logan
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

    831-460-7519 (voice)
    jlogan@usgs.gov
    Date: 2022 (process 4 of 5)
    Structure-from-motion (SfM) processing techniques were used to create point clouds, DSMs, and orthomosaic images in the Agisoft Photoscan/Metashape software package using the following workflow: 1. Initial image alignment was performed with the following parameters - Accuracy: 'high'; Pair selection: 'reference', 'generic'; Key point limit: 0 (unlimited); Tie point limit: 0 (unlimited). 2. Sparse point cloud error reduction was performed using an iterative gradual selection and camera optimization process with the following parameters: Reconstruction Uncertainty: 10; Projection Accuracy: 3. Lens calibration parameters f, cx, cy, k1, k2, k3, p1, and p2 were included in the optimization. Additional sparse points obviously above or below the true surface were manually deleted after the last error reduction iteration. 3. Ground control points (GCPs) were automatically detected using the 'Cross (non-coded)' option. False matches were manually removed, and all markers were visually checked and manually placed or adjusted if needed. 4. Additional sparse point cloud error reduction was performed using an iterative gradual selection and camera optimization process with the following parameters: Reprojection Error: 0.3. Lens calibration parameters f, cx, cy, k1, k2, k3, p1, and p2 were initially included in the optimization, but additional parameters k4, b1, b2, p3, and p4 were included once Reprojection Error was reduced below 1 pixel. Additional sparse points obviously above or below the true surface were manually deleted after the last error reduction iteration, and a final optimization was performed. 5. A dense point cloud was created using the 'high' accuracy setting, with 'aggressive' depth filtering. 6. A Digital Surface Model (DSM) with a native resolution of 4.8 centimeters per pixel was created using all points in the dense point cloud. 7. An RGB orthomosaic with a native resolution of 2.4 centimeters per pixel was created using the DSM as the orthorectification surface, and then exported to a GeoTIFF format with a 2.5-centimeter pixel resolution. Person who carried out this activity:
    Joshua Logan
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    2885 Mission Street
    Santa Cruz, CA
    US

    831-460-7519 (voice)
    831-427-4748 (FAX)
    jlogan@usgs.gov
    Date: 2022 (process 5 of 5)
    A uniform adjustment was applied to the orthomosaic to shift the image from the historic reference frame published in Smith and others, 2009 to the updated reference frame observed at the SFML benchmark during the 2017 survey (derived using the National Geodetic Survey (NGS) Online Positioning User Service (OPUS)).
    To ensure consistency with historic data sets, the original published position for the SFML benchmark was used for the RTK GPS base station position. Thus, the GCP positions and original SfM data products were consistent with the historic data presented in Smith and others, 2009. The SFML benchmark position published in that report is (in UTM zone 10 coordinates relative to the NAD83 reference frame): Northing: 4027605.397 Easting: 619388.986 Ortho. Ht. [m, NAVD88]: 322.418 (GEOID03)
    After the 2017-11-01 UAS survey, the 5:40 static GPS occupation on SFML was submitted to NGS OPS which derived the following current-epoch position for SFML: Northing: 4027605.687 Easting: 619388.761 Ortho. Ht. [m, NAVD88]: 322.359 (using GEOID03 separation = -33.047 m)
    Thus, the displacement between the 2009 published SFML position and the 2017-11-01 observed position is: dN: +0.290 meters dE: -0.225 meters dElev.: -0.059 meters
    This magnitude and direction of displacement is similar to those estimated for this location by the National Geodetic Survey Horizontal Time-Dependent Positioning (HTDP), shown below: HTDP OUTPUT, VERSION 3.4.0 DISPLACEMENTS IN METERS RELATIVE TO NAD_83(2011/CORS96/2007) FROM 11-05-2008 TO 11-01-2017 (month-day-year) FROM 2008.847 TO 2017.835 (decimal years) NAME OF SITE: SFML LATITUDE: 36 23 10.23945 N LONGITUDE: 121 40 7.85831 W NORTH: 0.341 meters EAST: -0.241 meters UP: -0.012 meters
    To produce the final data products for this data release, all data were transformed from the historic reference frame into the current-epoch reference frame consistent with the 2017-11-01 observed position for SFML. This transformation was done using a uniform horizontal and vertical adjustment.
    For adjustment of the orthomosaic, the following adjustment process was used: 1. The RGB orthomosaic was re-exported from Agisoft Metashape to a tiled GeoTIFF format with a 2.5-centimeter pixel resolution, with the following export bounds (these bounds allow for the final target raster origin to fall on a multiple of the raster cell size after the adjustment): xmin:619547.225 xmax:620062.225 ymin:4026185.710 ymax:4027051.710 2. The tiled geotiff were combined in a virtual raster (VRT) using gdalbuildvrt. 3. The VRT was shifted by the required dN and dE using gdal_translate: gdal_translate -a_ullr 619547.000 4027052.000 620084.600 4026181.600 input.vrt shifted.vrt 4. The shifted VRT was converted to a cloud optimized GeoTIFF for the final data product using gdal_translate: gdal_translate -b 1 -b 2 -b 3 -mask 4 -ot Byte -scale -of COG ^ -co BLOCKSIZE=256 -co COMPRESS=JPEG -co QUALITY=95 ^ -co RESAMPLING=AVERAGE -a_srs EPSG:6339 --config GDAL_TIFF_INTERNAL_MASK YES ^ --config GDAL_TIFF_OVR_BLOCKSIZE 128 -co NUM_THREADS=ALL_CPUS --config GDAL_CACHEMAX "50" ^ --config GDAL_MAX_DATASET_POOL_SIZE 512 ^ shifted.vrt LosPadresRes_2017-11-01_orthomosaic_25mm_.tif Person who carried out this activity:
    Joshua Logan
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

    831-460-7519 (voice)
    jlogan@usgs.gov
  3. What similar or related data should the user be aware of?
    Smith, D.P., Kvitek, R., Aiello, I., Iampietro, P., Quan, C., Paddock, E., Endris, C., and Gomez, K., 2009, Fall 2008 Stage-Volume Relationship for Los Padres Reservoir, Carmel Valley, California: Prepared for the Monterey Peninsula Water Management District.

    Online Links:

    Other_Citation_Details:
    Smith, D.P., Kvitek, R., Aiello, I., Iampietro, P., Quan, C., Paddock, E., Endris, C, and Gomez, K., 2009, Fall 2008 Stage-Volume Relationship for Los Padres Reservoir, Carmel Valley, California: Prepared for the Monterey Peninsula Water Management District. The Watershed Institute, California State University Monterey Bay, Publication no. WI-2009-2, 30 pp.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    Horizontal accuracy was estimated by comparing ground control point (GCP) positions measured with RTK GPS measurements to their SfM-estimated positions. Due to the time-intensive process of placing GCPs in the field, all available GCPs were used for registration and camera optimization in the SfM processing workflow during the creation of the final SfM data products. To evaluate the horizontal positional accuracy of the final SfM alignments, each GCPs was disabled one-at-a-time using a python script to create a 'temporary check point'. With a single GCP temporarily disabled, camera optimization was performed with all lens parameters fixed, and all other GCPs enabled. The residual errors of the check point relative to its GPS-measured position were recorded. After all temporary check point iterations were complete, the root-mean-square error (RMSE) and mean-absolute error (MAE) were calculated. The resulting horizontal RMSE was 0.025 meters (MAE 0.020 meters). The addition of the estimated horizontal GPS uncertainty (0.020 meters) in quadrature results in a total horizontal accuracy estimate of 0.032 meters. It should be noted that this error estimate is for areas of bare ground or low vegetation where GCPs were placed. Additional sources of error such as poor image-to-image point matching due to vegetation or uniform substrate texture (such as sand) resulting in poor surface reconstruction may cause localized errors in some portions of the point clouds to exceed this estimate.
  3. How accurate are the heights or depths?
    Vertical positional accuracy was not evaluated for this data product.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None
Use_Constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The orthomosaic image is available as a Cloud Optimized GeoTIFF file.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data can be viewed with GIS software or other software capable of displaying geospatial raster data.

Who wrote the metadata?

Dates:
Last modified: 11-Jan-2023
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9J9CHOH/LosPadresReservoir_2017-11-01_orthomosaic_25mm_metadata.faq.html>
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