Lidar Error Dictionary part 2
The purpose of this dictionary is to provide standardized language to describe commonly encountered errors associated with lidar datasets submitted to the USGS data validation unit for ingestion into the National Map. This document will improve communication between 3D Elevation Program operations personnel, the project’s point of contact, contributors, partners, and contractors.
Download a pdf copy of this data dictionary
The error dictionary is in two parts--Part 1 (this page) covers Breakline, Classified Point Cloud, and Digital Elevation Model deliverables. Part 2 covers FGDC XML Metadata, Reports, Spatial Metadata, and Raster Metadata deliverables.
Part 2
Digital Elevation Model Deliverable
FGDC XML Metadata Deliverable
Reports Deliverable
Spatial Metadata Deliverable
Raster Metadata Deliverable
Does Not Match Project Extent Errors
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Deliverable: Digital Elevation Model (DEM)
Error type: Export
Errors that are related to or caused by the exportation process in creating rasters from point cloud data.
Error Type: Export
Error subtype: Interpolation
Definition: Any artifacts relating to interpolation of the DEM from the lidar point cloud that appear erroneous. This is to include edge artifacts.
Error subtype: Mismatch
Definition: Elevation changes or gaps between two or more DEM tiles.
Error subtype: Overlap
Definition: When two or more adjacent DEM tiles overlay one another instead of edge matching.
Error subtype: Void
Definition: A specific type of interpolation error that is an area lacking data in the DEM, not due to point misclassifications or data voids in the point cloud.
Error type: Properties
Characteristics of DEM raster files are incorrect for some or all tiles according to applicable USGS Lidar Base Specification or contract/task order.
Error subtype: Ground Sample Distance
Definition: The resolution of the DEM raster files is incorrect for some or all tiles.
Error subtype: NoData Value
Definition: The value used for ‘NoData’ is incorrect or more than one value was used. Guidance starting with LBS 2.1 states: “The NODATA value of '-999999' shall be defined in GDAL_NODATA tag #42113”.
Error subtype: Pixel Depth
Definition: The value range for DEM bit depth is incorrect. 32-bit depth is typical.
Error subtype: Raster Format
Definition: The DEM file format is incorrect and/or not the format contracted to be delivered for the project.
Error subtype: Spatial Reference
Definition: The Coordinate Reference System used for some or all DEM files is incorrectly formatted or does not match the projects required CRS.
Error subtype: Tile size is not an integer multiple of the ground sample distance
Definition: The tile size of some or all raster files is not evenly divisible by the ground sample distance.
Deliverable: FGDC XML Metadata
Error type: Content Inaccurate
There is incorrect information in the XML metadata files. Tag location and description of occurrence will be indicated in text field.
Error subtype: Spatial Reference
Definition: The Coordinate Reference System is incorrect and/or does not match the projects contracted CRS.
Error type: Failed Parser
FGDC XML Metadata parses with errors through the USGS Geospatial Metadata Validation Service.
Error subtype: Missing Elements
Definition: A required tag is missing from an XML metadata file.
Error subtype: Misplaced Elements
Definition: A tag is in the wrong section of an XML metadata file.
Error subtype: Elements with Improper Domains
Definition: A tag contains incorrect domain value in an XML metadata file.
Deliverable: Reports
To encompass all contractor delivered reports. For example, collection, survey, and processing report.
Error type: Content Inaccurate
Error subtype: n/a
Definition: There is incorrect information in a contractor report. Description of error will be in text field.
Error type: Missing Information
Error subtype: n/a
Definition: A required aspect of the report is missing. Description of error will be in text field.
Deliverable: Spatial Metadata
Includes all spatial features delivered with project that are not breaklines; for example, tile index, DPA/boundary, checkpoints, flight line index.
Error type: Incorrect Attribution
Error subtype: n/a
Definition: One or many aspects of the spatial features’ attribution is incorrect. Description of error will be in text field.
Error type: Incorrect Geometry
Error subtype: n/a
Definition: One or many aspects of the spatial features’ geometry is incorrect. Description of error will be in text field.
Deliverable: Raster Metadata
Includes all raster type deliverables that are not the DEM; for example, intensity imagery, digital surface models, swath separation images.
Error type: Properties
Characteristics of raster files are incorrect for some or all files according to applicable USGS Lidar Base Specification or contract/task order.
Error subtype: Ground Sample Distance
Definition: The resolution of the raster files is incorrect for some or all files.
Error subtype: NoData Value
Definition: The value used for ‘NoData’ is incorrect or more than one value was used.
Error subtype: Pixel Depth
Definition: The value range for raster bit depth is incorrect.
Error subtype: Rater Format
Definition: The raster file format is incorrect and/or not the format contracted to be delivered for the project.
Error subtype: Spatial Reference
Definition: The Coordinate Reference System does not match the projects required CRS.
Error subtype: Tile size is not an integer multiple of the ground sample distance
Definition: The tile size of some or all raster files is not evenly divisible by the ground sample distance.
Error type: Does Not Match Project Extent
Error subtype: n/a
Definition: A delivered raster metadata product does not match the project’s extent.