Certified Photogrammetrist Quality Control & Standards in Photogrammetry

Question 1

What does the ASPRS 2014 standard use instead of the traditional NMAS 90% circular error to define accuracy?

Accepted Answer

RMSE-based accuracy with separate thresholds for horizontal (RMSEx, RMSEy) and vertical (RMSEz) components

Answer

ASPRS 2014 replaced the circular error approach with RMSE-based accuracy metrics, separately specifying RMSEx, RMSEy, and RMSEz thresholds that are tied to the product's GSD or contour interval.

Question 2

What is the minimum number of independent check points recommended by ASPRS 2014 for a small project area (< 500 km²)?

Accepted Answer

At least 20 well-distributed independent check points

Answer

ASPRS 2014 recommends a minimum of 20 well-distributed independent check points for assessing accuracy on smaller project areas, ensuring statistical validity of the reported accuracy.

Question 3

What is 'QA/QC' in the context of a photogrammetric mapping project?

Accepted Answer

Quality Assurance (process controls) and Quality Control (product inspection and testing) to ensure deliverables meet specifications

Answer

QA/QC encompasses Quality Assurance (systematic processes that prevent defects) and Quality Control (inspection and testing activities that detect and correct defects) in the production of photogrammetric deliverables.

Question 4

What is a 'metadata report' required to accompany photogrammetric deliverables?

Accepted Answer

Documentation describing data acquisition parameters, processing methods, datum/projection, accuracy, and data quality information

Answer

Metadata reports document all relevant information about data acquisition and processing—including flight parameters, camera calibration, datum, projection, accuracy statistics, and lineage—enabling proper use and archiving of deliverables.

Question 5

What is 'vertical datum' and why is it critical in photogrammetric elevation products?

Accepted Answer

The reference surface (e.g., NAVD 88, NGVD 29, ellipsoid) to which all elevations are referenced, determining how heights interoperate with other datasets

Answer

The vertical datum defines the reference surface (e.g., NAVD 88 in the US) to which all elevations are referenced; using an incorrect or undocumented datum causes systematic elevation offsets when data is integrated with other height information.

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Quality Control & Standards in Photogrammetry