NGP Standards and Specifications

3DEP Spatial Metadata

Spatial metadata for the 3D Elevation Program (3DEP) is now published and available by work unit in the Work unit Extent Spatial Metadata (WESM) geopackage. The WESM is a good source of information for current lidar data availability and basic information about lidar projects, including lidar quality level, data acquisition dates, and links to project-level metadata. 

3DEP Spatial Metadata 

The Work unit Extent Spatial Metadata (WESM) (alternative link on rockyweb: Work Unit Extent Spatial Metadata) is a good source of information for current lidar data availability and basic information about lidar projects, including lidar quality level, data acquisition dates, and links to project-level metadata.  

*Note that the Full Extent Spatial Metadata (FESM) has not been updated since May 2020 and will be removed from the site in the near future. 

Spatial Metadata Changes 

  • The Lidar Point Cloud (LPC) and source DEM (source) project extent spatial metadata are merged into a single master feature called the Work unit Extent Spatial Metadata (WESM).   

  • This feature contains work unit and project IDs, as well as a new field that indicates “status” by product type (LPC, source, 1m, and Seamless).   

    • The status refers to whether that product type meets 3DEP requirements, meets the requirements with variances, or does not meet 3DEP requirements. 
    • There is an “expected to meet” temporary placeholder for the 1m and Seamless products that is updated when the data validation of the entire project is complete.   

    • A reason code (text field) explains why a publication unit was placed in a specific category (for example, the reason why a dataset did not meet 3DEP standards).   
  • The WESM also contains links to the location of the source data (LPC and source DEMs) as well as the contractor and project metadata for each work unit.  The updated TESM and WESM files will be served as geopackages. 

For more information about product metadata, please see the 3DEP standards and specifications webpage

 

Related Changes to the Lidar Publishing Process 

Starting in May 2020, USGS modified the 3DEP lidar publishing procedures to increase the lidar data publishing rate, and to enable easier access to metadata and associated project reports.  

Data Releases 

  • The original source DEMs created by the lidar contractors (also called “original product resolution” [OPR] DEMs) and lidar point clouds are now published by individual work unit after data validation is complete, rather than waiting for the entire lidar project to be delivered and complete the USGS data validation process. The process is described in the diagram below. Contractor XML metadata will be provided on The National Map (TNM) by work unit via FTP

*Note that some web browsers such as Google Chrome and Microsoft Edge no longer support FTP.

Work Unit and project illustration

Work Units are a subset of a project. Lidar point clouds and 1-m digital elevation models are published by the Work Unit. See the Work unit Extent Spatial Metadata for spatial metadata and links to data and metadata. 

(Public domain.)

Work Unit and Project Reports, and Vertical Accuracy Information

  • A new work unit report is provided with each published work unit (beginning in early July 2020).

  • USGS provides contractor ground survey reports, checkpoints and USGS vertical accuracy test results at the project level via FTP.

*Note that some web browsers such as Google Chrome and Microsoft Edge no longer support FTP.