GIS For Engineering (MCQ) 3 — Questions and Answers
Question 1: Which coordinate reference system (CRS) is the standard for GPS receivers and global web mapping services?
- NAD83
- WGS84 (EPSG:4326) (Correct answer)
- State Plane Coordinate System
- UTM Zone 10N
Correct answer: WGS84 (EPSG:4326)
WGS84 (World Geodetic System 1984, EPSG:4326) is the global datum used by GPS satellites and services like Google Maps and OpenStreetMap.
Question 2: A GIS engineer needs to calculate the true area of a polygon stored in geographic coordinates (degrees). What must be done first?
- Convert to a raster
- Reproject to a local projected CRS with linear units (Correct answer)
- Add a Z value
- Convert to KML
Correct answer: Reproject to a local projected CRS with linear units
Area cannot be accurately calculated in degrees because degrees represent angles, not distances; reprojection to a projected CRS (e.g., UTM) with meter or feet units is required.
Question 3: Which remote sensing index is calculated as (NIR - Red) / (NIR + Red) and is used to assess vegetation health?
- NDWI
- NDVI (Correct answer)
- EVI
- SAVI
Correct answer: NDVI
NDVI (Normalized Difference Vegetation Index) uses the contrast between near-infrared and red bands to quantify vegetation density and health.
Question 4: In hydrology GIS, what operation fills sinks in a DEM before delineating watersheds?
- Slope calculation
- Fill Sinks (Depression Filling) (Correct answer)
- Contour generation
- Aspect analysis
Correct answer: Fill Sinks (Depression Filling)
Fill Sinks removes artificial depressions in a DEM that would otherwise create isolated drainage cells with no outlet, corrupting flow direction analysis.
Question 5: What does EPSG stand for in the context of spatial reference systems?
- Environmental Planning and Spatial Governance
- European Petroleum Survey Group (Correct answer)
- Extended Projection and Spheroid Geometry
- Earth Positioning Standards Group
Correct answer: European Petroleum Survey Group
EPSG (European Petroleum Survey Group) created and maintained the registry of coordinate reference systems; the registry is now managed by IOGP but the EPSG acronym is still used.
Question 6: Which type of GIS error occurs when two polygon boundaries that should coincide are digitized slightly apart, creating a sliver polygon?
- Attribute error
- Geometric sliver error (Correct answer)
- Projection mismatch
- Datum shift
Correct answer: Geometric sliver error
Sliver polygons are thin artifacts created when boundaries that should align are digitized with slight positional differences, a common problem when overlaying layers from different sources.
Question 7: In a GIS raster, what is the term for the phenomenon where a diagonal line appears as stair-steps due to grid cell size?
- Moire pattern
- Aliasing (Correct answer)
- Resampling artifact
- Band interleaving
Correct answer: Aliasing
Aliasing occurs in raster data when a feature is smaller than the pixel resolution, causing curves and diagonals to appear as stepped staircase patterns.
GIS For Engineering (MCQ) 3
Which coordinate reference system (CRS) is the standard for GPS receivers and global web mapping services?