Quality Control & Standards in Photogrammetry Flashcards

What is the FGDC (Federal Geographic Data Committee) Geospatial Positioning Accuracy Standard Part 3 primarily concerned with?

Answer: National Standard for Spatial Data Accuracy (NSSDA) — accuracy testing and reporting for digital geospatial data using RMSE

FGDC Part 3 (NSSDA) establishes the National Standard for Spatial Data Accuracy, defining RMSE-based testing and reporting protocols for horizontal and vertical accuracy of digital geospatial data.

In photogrammetric project specifications, what does 'NVA' stand for and how is it defined?

Answer: Non-Vegetated Accuracy — the vertical accuracy of the DEM in open, bare-earth areas, reported at the 95% confidence level

NVA (Non-Vegetated Vertical Accuracy) is the vertical accuracy of the DEM in open, non-vegetated areas assessed using check points, reported at the 95th percentile confidence level (≈ 1.9600 × RMSEz).

What is 'vegetated vertical accuracy' (VVA) and why is it reported separately from NVA?

Answer: VVA is the 95th percentile absolute error in vegetated areas; it is reported separately because vegetation obscures the ground, causing higher and more variable errors

VVA is the 95th percentile absolute error in vegetated areas; it is reported separately because vegetation canopy obscures the ground surface, causing higher and less predictable errors than in open areas.

What is a 'production specification' (project specification) in photogrammetric mapping?

Answer: The technical and contractual document defining all requirements for data acquisition, processing, accuracy, deliverables, and formats for a specific mapping project

A production specification is the comprehensive technical document—typically developed with or for the client—that defines all requirements including accuracy standards, feature content, formats, delivery schedule, and QC procedures for the project.

What does 'lineage' mean as a dimension of geospatial data quality?

Answer: A description of the history of the data—including source materials, collection methods, processing steps, and transformations applied

Lineage documents the origin and history of the data—what source materials were used, how they were collected, what processing and transformations were applied—enabling users to assess fitness for purpose and reproduce results.

According to ASPRS accuracy standards, what should be done when accuracy test results exceed the stated accuracy class threshold?

Answer: The data should be reported as meeting the next lower accuracy class, not the originally specified class

When RMSE results exceed the threshold for the specified accuracy class, the data must be reported as meeting only the lower accuracy class that its actual RMSE does satisfy, ensuring honest representation of the product's quality.