Ground control point locations for the UAS survey of the coral reef off Waiakane, Molokai, Hawaii, 24 June 2018

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Logan, Joshua B., and Storlazzi, Curt D., 20220321, Ground control point locations for the UAS survey of the coral reef off Waiakane, Molokai, Hawaii, 24 June 2018: data release DOI:10.5066/P9XZT1FK, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P9XZT1FK
   • https://www.sciencebase.gov/catalog/item/61ba8bbad34e9e224ac12fb7

   This is part of the following larger work.
   Logan, Joshua B., and Storlazzi, Curt D., 2022, Aerial imagery and structure-from-motion-derived shallow water bathymetry from a UAS survey of the coral reef off Waiakane, Molokai, Hawaii, June 2018: data release DOI:10.5066/P9XZT1FK, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

   Online Links:

   • https://doi.org/10.5066/P9XZT1FK
   • https://www.sciencebase.gov/catalog/item/61943c39d34eb622f68f530c

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -157.15679
   East_Bounding_Coordinate: -157.15388
   North_Bounding_Coordinate: 21.09352
   South_Bounding_Coordinate: 21.08451
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/61ba8bbad34e9e224ac12fb7?name=Waiakane_2018-06-24_GCP_browse.jpg&allowOpen=true (JPEG)

   Photographs showing examples of ground control points used for the UAS survey.

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 24-Jun-2018

   Currentness_Reference:

   ground condition at time data were collected

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: comma-delimited text
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (21)
   2. What coordinate system is used to represent geographic features?
      

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 4
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -159.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in meters
      The horizontal datum used is NAD83 (National Spatial Reference System PA11) (EPSG:6322).
      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.
      

      Vertical_Coordinate_System_Definition:

      Altitude_System_Definition:

      Altitude_Datum_Name: GRS 1980 Ellipsoid (EPSG:7019)
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:

      Explicit elevation coordinate included with horizontal coordinates

7. How does the data set describe geographic features?

   Attribute Table

   Table containing attribute information associated with the dataset (Source: Producer defined)

   pid

   Point ID (Source: producer defined) A unique identification code for the point.

   northing_utmz4_m

   Northing coordinate of data point relative to the NAD83 (National Spatial Reference System PA11) datum, projected in the Universal Transverse Mercator (UTM) Zone 4 North coordinate system, meters (EPSG:6634) (Source: Producer defined)

   Range of values
   Minimum:	2332953.915
   Maximum:	2333555.097
   Units:	meters

   easting_utmz4_m

   Easting coordinate of data point relative to the NAD83 (National Spatial Reference System PA11) datum, projected in the Universal Transverse Mercator (UTM) Zone 4 North coordinate system, meters (EPSG:6634) (Source: Producer defined)

   Range of values
   Minimum:	691572.329
   Maximum:	692112.683
   Units:	meters

   ellipsoid_ht_m

   Ellipsoid height in meters, referenced to the GRS 1980 ellipsoid (EPSG:7019). (Source: Producer defined)

   Range of values
   Minimum:	-0.995
   Maximum:	1.959
   Units:	meters

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
   • Curt D. Storlazzi
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?

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: 24-Jun-2018 (process 1 of 1)

   Survey control was established using twenty temporary ground control points (GCPs) distributed throughout the survey area. The GCPs were placed using a combination of kayaking, wading, and snorkeling. The GCPs consisted of: nine submerged targets consisting of small (80 centimeter X 80 centimeter) square tarps with black-and-white cross patterns anchored to the shallow (less than 1.5 meters deep) seafloor using 0.9 kilogram fishing weights; nine sub-aerial targets consisting of orange plastic five-gallon bucket lids (32 centimeter diameter) painted with a black “X” pattern and affixed in a horizontal orientation to vertical rebar stakes placed in areas of reef rubble to provide the targets with sufficient elevation to remain above the water surface during the survey; and two sub-aerial ground targets consisting of small (80 centimeter X 80 centimeter) square tarps with black-and-white cross patterns placed in the sand at the shoreline. Two of the submerged targets were disturbed by waves or currents during the survey and were not used for SfM processing. All GCP positions were measured using post-processed kinematic (PPK) GPS, using corrections from a GPS base station on a temporary benchmark (MK02) located approximately 1 kilometer away from the study area. Reference coordinates for MK02 were established using the mean position derived from four static GPS occupations with durations greater than 4 hours submitted to the National Geodetic Survey Online Positioning User Service (NGS 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

3. What similar or related data should the user be aware of?

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?
   GCP positions were measured using a survey-grade dual-frequency GPS receiver operating in post-processed-kinematic (PPK) mode. The GPS receiver was placed on a 2-meter fixed-height rod and set to occupy each GCP for a minimum occupation time of one minute. The PPK corrections were referenced to a GPS base station occupying a temporary benchmark (MK02) located approximately 1 kilometer away from the study area. Reference coordinates for MK02 were established using the mean position derived from four static GPS occupations with durations greater than 4 hours each submitted to the National Geodetic Survey Online Positioning User Service (NGS OPUS). The standard deviation of the four OPUS-derived horizontal positions was 0.004 meters. The mean reported horizontal precision of the PPK measurements was 0.015 meters, (standard deviation of 0.002). Due to the submerged position of some GCPs and well as the effects of wave and water motion during GCP placement and measuring, we estimate an additional 0.050 meters of uncertainty with these measurements. The sum of these independent estimated uncertainties in quadrature results in a total estimated horizontal uncertainty of 0.052 meters. Additional errors resulting from GCP disturbance by waves and currents during the survey are unknown.
3. How accurate are the heights or depths?
   GCP positions were measured using a survey-grade dual-frequency GPS receiver operating in post-processed-kinematic (PPK) mode. The GPS receiver was placed on a 2-meter fixed-height rod and set to occupy each GCP for a minimum occupation time of one minute. The PPK corrections were referenced to a GPS base station occupying a temporary benchmark (MK02) located approximately 1 kilometer away from the study area. Reference coordinates for MK02 were established using the mean position derived from four static GPS occupations with durations greater than 4 hours each submitted to the National Geodetic Survey Online Positioning User Service (NGS OPUS). The standard deviation of the four OPUS-derived vertical positions was 0.008 meters. The mean reported vertical precision of the PPK measurements was 0.028 meters, (standard deviation of 0.006). Due to the submerged position of some GCPs and well as the effects of wave and water motion during GCP placement and measuring, we estimate an additional 0.050 meters of uncertainty with these measurements. The sum of these independent estimated uncertainties in quadrature results in a total estimated horizontal uncertainty of 0.057 meters. Additional errors resulting from GCP disturbance by waves and currents during the survey are unknown.
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?

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 GCP locations are available in comma-delimited text format (Waiakane_2018-06-24_GCP.csv).
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?
   • Availability in digital form:

     Data format:	The csv file contains coordinates of ground control point locations. in format comma-delimited text (version Notepad++ v 8.1.9.3) Size: 0.001
     Network links:	https://www.sciencebase.gov/catalog/file/get/61ba8bbad34e9e224ac12fb7?name=Waiakane_2018-06-24_GCP.csv https://www.sciencebase.gov/catalog/item/61ba8bbad34e9e224ac12fb7 https://doi.org/10.5066/P9XZT1FK

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?
   The downloadable data file is available in comma-separated values (CSV) spreadsheet format. Text editing software can be used to open the file, as well as spreadsheet programs, such as Microsoft Excel.

Who wrote the metadata?

Dates:

Last modified: 21-Mar-2022

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)