10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
These 10 free CRST questions are organized by exam domain, so you can see how each part of the Certified Remote Sensing Technologist (CRST) blueprint is tested. Reveal the answer and explanation under each question.
A GNSS survey provides ellipsoidal heights, while a terrain model uses orthometric heights tied to a specified vertical datum. Both datasets use meters. What must be established before their elevations are compared?
Correct answer: D - A compatible vertical reference and the applicable geoid transformation
Control points used to fit an orthomosaic have very small residuals. Independent surveyed checkpoints, however, show a consistent 1.8-m eastward offset across the site. What is the most defensible interpretation?
Correct answer: D - A systematic error requires investigation despite the good control-point fit
A sensor records every pixel on a bright roof at its maximum digital value, although the roof contains panels with different brightness. The raw data confirm detector saturation. Which action can recover measurements of the differences between panels?
Correct answer: B - Reacquire the roof using settings that avoid saturation
An emergency team needs a current image of a broad, open floodplain during persistent cloud cover at night. Each available sensor has adequate spatial resolution and can acquire within the response window. Which option is most suitable for obtaining surface observations under these conditions?
Correct answer: C - An active microwave radar imager designed for surface mapping
A mapper must distinguish 6-m-wide shelterbelts from the fields beside them. The current 20-m imagery has suitable spectral bands, but most shelterbelt pixels contain a mixture of trees and crops. Which replacement dataset most directly addresses this limitation?
Correct answer: C - 2-m imagery with comparable bands and adequate signal quality
An airborne scanner records alternating bright and dark columns over a uniform calibration target. The stripes remain tied to detector columns in successive images, while control features align correctly. Which correction should be investigated first?
Correct answer: A - Detector-specific gain and offset calibration
A supervised forest map labels many shaded conifer stands as water. Field checks confirm the stands are conifers, and the training data contain sunlit conifers but no shaded examples. What is the best first revision to the classification?
Correct answer: D - Add verified shaded-conifer samples and retest on independent samples
Two well-registered Landsat scenes cover the same fields at comparable growth stages, but one was acquired through more atmospheric haze. An analyst wants to measure changes in surface reflectance. Which comparison is best supported?
Correct answer: C - Compare consistently corrected surface reflectance with invalid pixels masked
A last-return lidar surface follows both the ground and the roofs of several buildings. A colleague proposes using it directly as a bare-earth terrain model because each pulse's last return is included. What is the best next step?
Correct answer: A - Classify and verify ground points before generating the terrain surface
During a U.S. Part 107 mapping flight, a helicopter approaches the survey area at low altitude. Continuing the current flight line would create a conflict, and a safe landing area is available. What should the remote pilot do?
Correct answer: B - Yield immediately and maneuver or land safely to remain clear
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