Certified Photogrammetrist Photogrammetric Product Generation 2

Question 1

What is the ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) Class 1 horizontal accuracy for 1 cm GSD imagery?

Accepted Answer

RMSEx and RMSEy ≤ 1.0 cm, with 95% confidence radius ≤ 1.7 cm

Answer

Under ASPRS 2014 standards, Class 1 horizontal accuracy for 1 cm GSD specifies RMSEx and RMSEy ≤ 1.0 cm (equal to the GSD), with a 95% radial confidence of ≤ 1.7 cm.

Question 2

What is 'vertical accuracy' in the context of DEM quality assessment?

Accepted Answer

A statistical measure (typically RMSE) of elevation differences between the DEM and ground-truth check points

Answer

Vertical accuracy for a DEM is typically expressed as the RMSE of elevation differences between DEM values and independently surveyed check points, following standards like ASPRS 2014 or FEMA guidelines.

Question 3

What is a 'mosaic dodging' or 'color balancing' algorithm used for in orthomosaic production?

Accepted Answer

Adjusting the brightness and color of individual photos to achieve a visually seamless mosaic

Answer

Dodging and color balancing algorithms adjust brightness, contrast, and color of individual source orthophotos so that the final mosaic has a uniform appearance without visible lighting differences.

Question 4

What does 'resampling' mean in the context of raster photogrammetric products?

Accepted Answer

The process of computing pixel values at new grid positions during geometric transformations (e.g., bilinear, cubic convolution)

Answer

Resampling computes new pixel values during raster transformation using interpolation methods—nearest neighbor preserves sharp edges, bilinear smooths slightly, and cubic convolution provides the best quality at higher cost.

Question 5

What is 'hypsographic tinting' in topographic map design?

Accepted Answer

The use of graduated colors to represent elevation zones, typically from green (lowlands) to brown/white (highlands)

Answer

Hypsographic tinting uses a graduated color scheme keyed to elevation, traditionally ranging from green at low elevations through yellow, orange, brown, and white at high elevations to visually communicate terrain relief.

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Practice Test

Certified Photogrammetrist Photogrammetric Product Generation 2