WESM Data Dictionary: Reason Codes: Lidar Point Cloud

By NGP Standards and Specifications

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.

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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)

Meets with variance
Does not meet

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.