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WESM Data Dictionary: Reason Codes: Lidar Point Cloud

In addition to general attributes, the Work Unit Extent Spatial Metadata (WESM) includes information on how data in a given work unit relates to 3D Elevation Program (3DEP) elevation product specifications. This information is shown in the product status codes. Product status codes include codes for categories and reasons. Reasons for the Lidar Point Cloud (LPC) are discussed here. 

WESM Product Status Codes: LPC Reasons

For more information about the product status codes, please see the WESM Introduction page

Introduction

A work unit’s reason code gives the primary reason why it was assigned to a particular category. The reason codes are typically unique per category and product combination, though some codes are used for several products for some of the categories.

Links to other reason code attributes by product (links to other pages)
Quick links to sections by category (on this page)

Reason Codes for the Lidar Point Cloud

lpc_reason

  • Description: Lidar point cloud reason code
  • Definition: Used to store the reason code for the LPC
  • Format: text
  • Length: 100 characters
  • Valid values:

Category

Reason code

Expected to meet

Awaiting final absolute vertical accuracy assessment

Under review

Awaiting final absolute vertical accuracy assessment

Meets

Meets 3DEP LPC requirements

Meets with variance

See reason code list below

Does not meet

See reason code list below

Not applicable

Not applicable

 

Reason codes for category Meets with variance

Reason Code

Definition

Absolute vertical accuracy does not meet minimum specification - extraordinary circumstance

Absolute Vertical Accuracy is unable to meet requirements due to ground movement during collection. This may include tectonic or eruptive activity or similar, unique geological circumstance.

Check points - alternate

ASPRS-defined number or distribution of NVA and VVA check points may not meet the specification for documented reasons. Alternative criteria used, approved in advance.

Data voids - delineated

Voids in LPC in areas delineated and agreed to in advance.

GPS time - other method

LPC collected using a sensor or method that does not record adjusted GPS time. Discussed and agreed to in advance.

Ground conditions during collection - delineated

Areas of known flooding or ponding of water or non-perennial snow cover in project occurring in collection area, delineated and approved in advance.  See project metadata for details.

Incorrect Datum - alternate

Alternate datum agreed to in advance.

LPC meets v1.0 or draft LBS

Lidar point cloud data that is >= 2ppsm and <= 10 cm RMSEz that meets density, classification and accuracy requirements with USGS Lidar Base Specification v1.0 or draft version products

Meets 3DEP LPC requirements - provisional

Data that meets point cloud density, accuracy, and classification requirements but are not required to meet the LBS v1.2 or later version products where it is not possible due to the provisional aspects of the sensor, collection, formatting, or processing.

Metadata does not meet requirements - alternate

Metadata provided, alternative criteria approved.

Nonstandard coordinate system - alternate

Nonstandard coordinate system, agreed to in advance.

Nonstandard WKT - alternate

Nonstandard WKT specification used, agreed to in advance.

Point classification - alternate

Alternate classification scheme used, approved in advance.

Point data not classified - alternate

Delivered point data was not classified, but was agreed to in advance.

Relative vertical accuracy - interswath - delineated

Significant issues with swath to swath alignment identified in point cloud data in delineated areas.

Relative vertical accuracy - intraswath - delineated

Significant issues with smooth surface precision discussed and agreed to in advance.

Restricted area

Restricted Area (military, tribal lands, and/or other)

Swath separation images - alternate

SSI's were not required, approved in advance.

Tiles do not meet specification -  alternate

Tiling scheme does not meet specification but was approved in advance.

Vegetation conditions during collection - delineated

Collection during leaf-on conditions planned and agreed to in advance.  See project metadata for details.

VVA does not meet minimum specification - dense vegetation

Vegetated vertical accuracy does not meet the minimum requirement in the lidar base specification in known areas of dense vegetation that are approved in advance and are delineated as areas of low confidence.

Reason codes for category Does not meet

Reason code

Definition

Absolute horizontal accuracy

Absolute horizontal accuracy does not meet requirements, ASPRS statement not provided.

Breaklines not delivered

Breaklines were created and used to classify the Lidar Point Cloud but not delivered.

Check points

ASPRS-defined number or distribution of NVA and VVA check points does not meet the specification.

Data voids

Unacceptable voids in LPC that do not meet specification.

Failed boundary requirements

LPC and associated datasets delivered with unacceptable issues related to DPA.

Failed LAS file format

Data not delivered in required LAS file format or incorrect point data record.

File or point source IDs do not meet specification

File IDs are non-unique, incorrect point source ID usage, or non-zero file source ID for tiled LAS files.

GPS time

GPS time not recorded properly.

Ground conditions during collection

Unacceptable areas of flooding or ponding of water or non-perennial snow cover in project occurring in collection area.  See project metadata for details.

Improper use of overlap bit flag

Overlap bit flag used in 3DEP collection.

Improper use of withheld bit flag

Geometrically valid points classified as withheld or withheld flag not applied to geometrically invalid points.

Majority of swath overlap flagged as withheld, precluding ability to assess interswath.

Inconsistent point classification

Noticeable variations in the character, texture, or quality of the classification between tiles, swaths, lifts, or other non-natural divisions.

Incorrect Datum

Datum does not meet basic requirements.

Intensity requirements not met

Intensity values not populated in LAS file, do not meet ASPRS LAS specification, use a non-linear normalization, or are stretched.

Lidar points duplicated

LPC contains duplicated lidar points which is not acceptable.

LPC being made available

LPC dataset that does not meet specification being made available due to national importance.

LPC not available

Full lidar point cloud is not available.

LPC predates v.1.0 or draft LBS.

Lidar point cloud data that does not meet density, classification and accuracy requirements with USGS Lidar Base Specification v1.0 or draft version products.

Metadata does not meet requirements

Metadata missing or does not meet requirements. See project metadata for details.

Nonstandard coordinate system

Coordinate system used is not recognized by the EPSG or is non usable for some other reason.

Nonstandard WKT

Nonstandard, unusable WKT provided.

Nonuniform

Distribution of geometrically useable points is nonuniform or irregular. The dataset is not usable for 3DEP purposes.

NVA > 10CM RMSEz

Non-vegetated absolute vertical accuracy > 10 cm RMSEz.

Point classification

Nonstandard, unapproved point classification scheme used or points improperly classified.

Point data not classified

Delivered point data was not classified.

Point density < 2 ppsm

Lidar point density < 2 ppsm.

Relative vertical accuracy - interswath

Significant issues with swath to swath alignment identified in point cloud data, not delineated.

Relative vertical accuracy - intraswath

Significant issues with smooth surface precision identified in point cloud data, not delineated.

Swath separation images

SSIs missing or made incorrectly.

Tiles do not meet specification

Tiling scheme does not meet specification, not approved and is not usable.

Unvalidated Dataset

Dataset not reviewed by USGS for inclusion into the 3D Elevation Program. Issues may exist with this dataset in addition to any known issues that may or may not have been listed.

Vegetation conditions during collection

Collection during leaf-on conditions, not agreed to in advance and resulting in data not meeting requirements.   See project metadata for details.

VVA does not meet minimum specification

Vegetated vertical accuracy does not meet the minimum requirement in the lidar base specification.