This revision adds a requirement specifying the file format, required utilization and format of the horizontal and vertical coordinate reference system for the file, and minimum required attribution of survey points (checkpoints and control points) associated with a lidar dataset.
Status of this revision: Published in Lidar Base Specification 2022 rev. A
Survey Point Delivery
Survey Points associated with the project shall be delivered in GeoPackage file format, consistent with the most recent published version of the GeoPackage Encoding Standard (presently OGC GeoPackage Encoding Standard (2021)).
- The GeoPackage will contain all checkpoints utilized to validate the vertical accuracy of the project. Any checkpoints that were not utilized in the verification of the final vertical accuracy assessment are prohibited.
- The GeoPackage may also contain all the control points associated with the project.
- The GeoPackage shall be in the same CRS as the lidar data.
- The CRS information of the GeoPackage shall adhere to all Well-Known Text requirements (in section ___ of this specification), with only the following exceptions:
- The CRS information shall be recorded in the gpkg_spatial_ref_sys_table as defined in OGC GeoPackage Encoding Standard (2021).
- The GeoPackage shall contain a single CRS entry.
- GDAL version 2.4.1 or later or as otherwise agreed to in advance and specified in the Task Order, shall be used to populate the gpkg_spatial_ref_sys_table of the GeoPackage as defined in OGC GeoPackage Encoding Standard (2021).
- The point features within the GeoPackage shall be Z-enabled.
- The name of the GeoPackage shall contain only the USGS defined name of a project appended with “_Survey_Points” (for example, FL_Everglades_2020_D20_Survey_Points).
- The GeoPackage shall possess the following minimum attribution:
- unique_identifier (Text format) – Unique identifier that distinguishes the specific point from all other points within the file. The identifier shall be consistent with associated survey reports and images.
- point_type (Text format limited to 10 characters in length) – populated with one of the following values:
- BVA (Bathymetry vertical accuracy checkpoint)
- comment (Text format) – May be null or empty. This field is for additional information the producer wishes to include regarding a specified point (for example, “bathymetry checkpoint at the edge of a waterbody.”)
- collection_date – (Date format) The specific date the point was surveyed expressed as yyyy-mm-dd.
- source_geoid – (Text format) The source geoid.
- source_horizontal_epsg – (Integer format) The source horizontal epsg.
- source_horizontal_unit – (Text format) The source horizontal unit of measurement.
- metre (provided as an option to keep the unit of measure consistent with possible versions of the WKT associated with the GeoPackage)
- U.S. Survey Feet
- International Feet
- source_vertical_epsg – (Integer format) The source vertical epsg.
- source_vertical_unit – (Text format) The source vertical unit of measurement.
- source_easting – (Real format) The source easting coordinate, not to exceed three decimal places in precision.
- source_northing – (Real format) The source northing coordinate, not to exceed three decimal places in precision.
- source_elevation – (Real format) The source elevation, not to exceed three decimal places in precision.
- project_id – numerical value of project assigned by USGS (previously referred to as the work package identification for a project).
Open Geospatial Consortium, Inc. (OGC), 2021, OGC® GeoPackage Encoding Standard (ver. 1.3): Open Geospatial Consortium, Inc. [Available at https://docs.ogc.org/is/12-128r17/12-128r17.html.]