GIS For Engineering (MCQ) 2 — Questions and Answers
Question 1: Which map projection preserves area but distorts shape, making it useful for thematic maps showing quantity?
- Mercator
- Albers Equal-Area Conic (Correct answer)
- Stereographic
- Transverse Mercator
Correct answer: Albers Equal-Area Conic
Albers Equal-Area Conic preserves area (equal-area property), making it ideal for thematic maps where relative sizes must be accurate.
Question 2: In GIS topology, what rule ensures that no two polygon features in a layer share the same area (overlap)?
- Must Not Have Gaps
- Must Not Overlap (Correct answer)
- Must Be Covered By
- Must Contain Point
Correct answer: Must Not Overlap
The 'Must Not Overlap' topology rule enforces that polygon features within the same layer cannot share the same spatial area.
Question 3: A surveyor uses a total station to collect XYZ coordinates. Which GIS data model best stores this point cloud for terrain modeling?
- Shapefile
- LiDAR LAS format (Correct answer)
- GeoJSON
- KML
Correct answer: LiDAR LAS format
LAS (and LAZ compressed) format is the standard for storing point cloud data including XYZ coordinates, intensity, and return number from total stations and LiDAR sensors.
Question 4: What does a Thiessen (Voronoi) polygon represent in engineering GIS applications?
- The drainage area contributing to a single stream segment
- The area closer to one point than to any other point in a set (Correct answer)
- The buffer zone around a linear feature
- The convex hull of a point dataset
Correct answer: The area closer to one point than to any other point in a set
Thiessen polygons partition space so that every location within a polygon is closer to its seed point than to any other seed point in the dataset.
Question 5: When performing a site suitability analysis, which GIS operation combines multiple raster layers using weighted importance scores?
- Map Algebra Overlay
- Weighted Overlay (Correct answer)
- Union
- Clip
Correct answer: Weighted Overlay
Weighted Overlay multiplies each raster layer by its assigned weight and sums the results to produce a composite suitability score.
Question 6: What is the primary purpose of a spatial index (such as an R-tree) in a GIS database?
- To store attribute data more efficiently
- To speed up spatial query retrieval by organizing features by location (Correct answer)
- To project coordinates into a different CRS
- To validate topology rules
Correct answer: To speed up spatial query retrieval by organizing features by location
R-tree and similar spatial indexes organize features by bounding rectangles so the database can quickly eliminate non-candidate features during spatial queries.
Question 7: In a GIS network dataset, what attribute is typically assigned to road segments to model traffic travel time?
- Shape_Length only
- Impedance value (e.g., minutes) (Correct answer)
- Object ID
- Topology rank
Correct answer: Impedance value (e.g., minutes)
Impedance values (commonly in minutes or seconds) represent the cost of traversing a network edge and are the key input for routing and service area analysis.
GIS For Engineering (MCQ) 2
Which map projection preserves area but distorts shape, making it useful for thematic maps showing quantity?