Surveying Principles & Spatial Analysis Flashcards
7 cards from real Certified Photogrammetrist practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Surveying Principles & Spatial Analysis flashcards as text
In differential leveling, a benchmark has an elevation of 100.00 ft, the backsight on it is 4.25 ft, and the foresight on a new point is 2.10 ft. What is the elevation of the new point?
Answer: 102.15 ft
HI = 100.00 + 4.25 = 104.25 ft, and elevation = 104.25 - 2.10 = 102.15 ft.
Why do surveyors keep backsight and foresight distances approximately equal in differential leveling?
Answer: To eliminate collimation error and curvature and refraction effects
Equal sight lengths cause collimation, curvature and refraction errors to cancel between the two readings.
What is the approximate combined curvature and refraction correction for a horizontal sight of 1 km?
Answer: 0.067 m
The combined correction is about 0.0675 K^2 m, giving roughly 0.067 m at 1 km.
What enables Real-Time Kinematic (RTK) GNSS to achieve centimeter-level positioning?
Answer: Carrier-phase measurements with corrections from a nearby base station
RTK resolves carrier-phase integer ambiguities using real-time corrections from a reference receiver.
A GNSS observation session reports a PDOP of 1.8. What does this indicate?
Answer: Strong satellite geometry favorable for positioning
Low PDOP values indicate well-distributed satellites and stronger position solutions.
A GNSS antenna set up next to a metal-sided building produces noisy, biased results. What error source is most likely?
Answer: Multipath
Multipath occurs when signals reflect off nearby surfaces before reaching the antenna.
Which NGS service lets a user upload static GNSS data and receive coordinates tied to the National Spatial Reference System?
Answer: OPUS
OPUS (Online Positioning User Service) processes static GNSS files against CORS stations to return NSRS coordinates.
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Sources & references
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- asprs.org — Test delivery, eligibility, fees, registration deadline, retake fee, retake policy, score release, time limit, score validity · verified Nov 2026
- prometric.com — Registration · verified Nov 2026