OSINT Geospatial Intelligence & Mapping 3 — Questions and Answers
Question 1: What is 'reverse image geolocation' as practiced in OSINT investigations?
- Converting GPS metadata embedded in an image to map coordinates
- Analyzing visual cues within an image to determine where it was photographed (Correct answer)
- Searching image databases by MD5 hash to find duplicates
- Extracting geotags from social media photo APIs
Correct answer: Analyzing visual cues within an image to determine where it was photographed
Reverse image geolocation uses landmarks, terrain, shadows, vegetation, signage, and architecture visible in a photo to pinpoint its capture location without relying on metadata.
Question 2: An OSINT analyst is mapping vessel movements near a disputed maritime boundary. Which free resource provides real-time and historical AIS (Automatic Identification System) data?
- Flightradar24
- MarineTraffic (Correct answer)
- OpenSeaMap
- ADS-B Exchange
Correct answer: MarineTraffic
MarineTraffic aggregates AIS transponder data from a global network of receivers and provides both live and historical ship position data.
Question 3: Which map projection is used by web mapping services like Google Maps and OpenStreetMap because it renders square tiles efficiently?
- Mercator (specifically Web Mercator / EPSG:3857) (Correct answer)
- Robinson Projection
- Mollweide Equal-Area
- Azimuthal Equidistant
Correct answer: Mercator (specifically Web Mercator / EPSG:3857)
Web Mercator (EPSG:3857) projects the Earth onto a square, enabling fast tile-based rendering but distorting area near the poles.
Question 4: During change detection analysis, an analyst compares two satellite images of an airfield taken 6 months apart. What is the primary purpose of performing image co-registration before comparison?
- To enhance color saturation for better visualization
- To align both images to the same spatial reference so pixel-level differences reflect real changes (Correct answer)
- To remove cloud cover from both images simultaneously
- To increase the spatial resolution of the older image
Correct answer: To align both images to the same spatial reference so pixel-level differences reflect real changes
Co-registration geometrically aligns images so that corresponding pixels represent the same ground location, eliminating false change detections caused by misalignment.
Question 5: Which OSINT source would an analyst consult to determine the historical ownership and registration jurisdiction of a specific plot of land?
- OpenStreetMap changeset history
- County or municipal cadastral / property records database (Correct answer)
- Sentinel-2 land cover classification
- FAA sectional aeronautical charts
Correct answer: County or municipal cadastral / property records database
Cadastral databases (often maintained by county assessors or land registries) record parcel boundaries, ownership history, and legal descriptions.
Question 6: An analyst wants to measure the precise distance between two structures visible in a high-resolution satellite image. Which approach is most accurate?
- Counting pixels and multiplying by the declared spatial resolution (GSD) (Correct answer)
- Measuring with a screen ruler and scaling by the map scale bar
- Using the image EXIF focal length data
- Estimating based on known vehicle dimensions parked nearby
Correct answer: Counting pixels and multiplying by the declared spatial resolution (GSD)
Multiplying the pixel count by the image's Ground Sample Distance (GSD) gives a metric distance measurement, provided the image is orthorectified.
Question 7: What is the significance of the 'nadir point' in aerial or satellite imagery?
- The point on the ground directly below the sensor, where distortion is minimal (Correct answer)
- The highest elevation point visible in the image scene
- The center pixel of a processed orthoimage
- The GPS coordinate stamped in the image header
Correct answer: The point on the ground directly below the sensor, where distortion is minimal
The nadir is the point on the ground directly beneath the sensor; objects near the nadir appear with minimal perspective distortion compared to those at the image edges.
OSINT Geospatial Intelligence & Mapping 3
What is 'reverse image geolocation' as practiced in OSINT investigations?