WESM Data Dictionary: General Attributes

collect_start

• Description: Collection start date
• Definition: Date data collection for the work unit was started.
• Type: Date
• Range: 1947-01-01 to present
• Format: ISO-8601 date string, UTF-8, stored as text: YYYY-MM-DD
• Example: 2020-04-08

collect_end

• Description: Collection end date
• Definition: Date data collection for the work unit ended.
• Type: Date
• Range: 2001-01-30 to present
• Format: ISO-8601 date string, UTF-8, stored as text: YYYY-MM-DD
• Example: 2020-05-04

ql

• Description: Quality level
• Definition: The 3DEP Quality Level of the work unit. See the corresponding Lidar Base Specification (as indicated by the “spec” attribute) for the requirements for the ql.
• Type: Text
• Length: 50 characters
• Format: Typically "QL #" where # is 0, 1, 2, 3, 5 and corresponds to the quality level.
• Occasionally: "Other", usually for legacy data or when the QL does not apply.  QL 5 is used exclusively for IfSAR collections in Alaska.
• Valid values:
  • QL 0
  • QL 1
  • QL 2
  • QL 3
  • QL 5
  • Other
• Example: QL 2

spec

• Description: Specification
• Definition: Specification under which the project was collected.
• Type: Text
• Length: 50 characters
• Valid values:
  • Draft Version 12
  • Draft Version 13
  • USGS Lidar Base Specification 1.0
  • USGS Lidar Base Specification 1.2
  • USGS Lidar Base Specification 1.3
  • USGS Lidar Base Specification 2.0
  • USGS Lidar Base Specification 2.1
  • USGS Lidar Base Specification 2020 rev. A
  • USGS Lidar Base Specification 2021 rev. A
  • USGS Lidar Base Specification 2022 rev. A
  • USGS Lidar Base Specification 2023 rev. A
  • USGS Lidar Base Specification 2024 rev. A
  • Other
• Example: USGS Lidar Base Specification 2.1

p_method

• Description: Production method
• Definition: The method used to capture the data in the work unit.
• Type: Text
• Length: 50 characters
• Format: Variable
• Valid values:
  • Flash lidar
  • Geiger-mode lidar
  • Ifsar
  • Linear-mode lidar
  • Single photon lidar
  • Topobathymetric lidar
  • Tobobathymetric model
  • Other
• Example: linear-mode lidar

dem_gsd_meters

• Description: DEM ground sample distance
• Definition: Spatial resolution (cell size) of the bare-earth source Digital Elevation Model (DEM), in meters.Type: Double
• Range: Greater than 0
• Example:  0.308

horiz_crs

• Description: Horizontal coordinate reference system
• Definition:  Reference code to the horizontal coordinate reference system. The code refers to a listing in the International Association of Oil & Gas Producers’ (IOPG’s) EPSG Geodetic Parameter Dataset. The code itself is an integer stored as text.
• Type: Text
• Length: 500 characters
• Format: Four to six characters or blank
• Example: 6341

vert_crs

• Description: Vertical coordinate reference system
• Definition: Reference code to the horizontal coordinate reference system. The code refers to a listing in the International Association of Oil & Gas Producers’ (IOPG’s) EPSG Geodetic Parameter Dataset. The code itself is an integer stored as text.
• Type: Text
• Length: 500 characters
• Format: Four-digit code. May occasionally contain a brief explanatory phrase if a code is not available, such as “Ellipsoidal” or “Local mean sea level in Meters” or “Unknown”.
• Example: 5703

geoid

• Description: Geoid
• Definition: Geoid used in project and/or work unit
• Type: Text
• Length: 200 characters
• Format: Follows the usage of the National Geodic Survey
• Example: GEOID12B

lpc_pub_date

• Description: LPC publication date
• Definition: Date the Lidar Point Cloud (LPC) was published
• Type: Date
• Format: ISO-8601 date string, UTF-8, stored as text: YYYY-MM-DD
• Example: 2021-06-02

sourcedem_pub_date

• Description: Source DEM publication date
• Definition: Date the bare-earth source Digital Elevation Model (DEM) was published.
• Type: Date
• Format: ISO-8601 date string, UTF-8, stored as text: YYYY-MM-DD
• Example: 2021-05-25

lpc_link

• Description: Lidar Point Cloud hyperlink
• Definition: HTTPS protocol hyperlink either to the Work Unit folder containing the LPC dataset folder or to the folder containing the LPC datasets. The LPC datasets are stored as compressed LAZ files in a folder named “LAZ” or “laz”. Not every work unit will have a corresponding LAZ folder. For instance, IfSAR datasets do not have a point cloud so there will be no links to the LPC for those work units.   
• Type: Text
• Valid values: Hyperlink or blank
• Format: (typically) https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Proje…

sourcedem_link

• Description: Source DEM hyperlink
• Definition: HTTP protocol hyperlink to the Work Unit folder containing the TIFF dataset folder which contains the DEM TIFF files. This will be blank for some work units, such as legacy data, which do not have source DEMs available.      
• Type: text
• Valid values: Hyperlink or blank
• Format: (typically) http://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevat…;

metadata_link

• Description: Hyperlink to the project metadata.
• Definition: HTTP protocol hyperlink to the Work Unit folder containing the TIFF dataset folder which contains the DEM TIFF files. This will be blank for some work units, such as legacy data, which do not have source DEMs available.     
• Type: Text
• Valid values:
• Format: (typically)
  • http://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevat…, or
  • http://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevat…]

lpc_update

• Description: LPC update date
• Definition: The date an update was made to either the storage path or one or more lidar point cloud data files.  If this field is blank then either there has been no update to the files or the file storage location since the data was published or, for any before 2023-03-01, updates were not noted in this column and will be blank even if there were updates to files or storage path after the original publication date. 
• Type: Date
• Range: 2023-03-01 to present
• Format: ISO-8601 date string, UTF-8, stored as text: YYYY-MM-DD
• Example:

sourcedem_update

• Description: Source DEM update date
• Definition: The date an update was made to either the storage path or one or more source DEM data files.  If this field is blank then either there has been no update to the files or the file storage location since the data was published or, for any pub dates before 2023-03-01, updates were not noted in this column and will be blank even if there were updates to files or storage path after the original publication date. 
• Type: Date
• Range: 2023-03-01 to present
• Format: ISO-8601 date string, UTF-8, stored as text: YYYY-MM-DD
• Example: 2023-05-10