GIS Geospatial Data Fundamentals 2 — Questions and Answers
Question 1: Which data model represents geographic features as a continuous grid of cells, each with an assigned value?
- Vector
- Raster (Correct answer)
- TIN
- Network
Correct answer: Raster
Raster data divides space into a regular grid of cells (pixels), each storing a value such as elevation or land cover type.
Question 2: What term describes the minimum distance between two distinguishable features in a raster dataset?
- Scale
- Accuracy
- Spatial resolution (Correct answer)
- Precision
Correct answer: Spatial resolution
Spatial resolution defines the smallest feature a raster can represent, typically expressed as cell size (e.g., 30 meters per pixel).
Question 3: In GIS, what does a 'topology' define?
- The color scheme of a map
- Spatial relationships and connectivity rules between features (Correct answer)
- The coordinate reference system of a dataset
- The file format used to store vector data
Correct answer: Spatial relationships and connectivity rules between features
Topology encodes the spatial relationships (adjacency, connectivity, containment) among vector features and enforces rules like 'no gaps between polygons.'
Question 4: Which attribute type is best suited for storing a street address in a GIS attribute table?
- Integer
- Float
- Text/String (Correct answer)
- Boolean
Correct answer: Text/String
Street addresses contain alphanumeric characters that cannot be stored as numeric types, so a text/string field is required.
Question 5: What is the purpose of a spatial index in a GIS database?
- To reproject data into a new coordinate system
- To speed up spatial queries by organizing feature locations (Correct answer)
- To convert raster data to vector format
- To calculate the area of polygon features
Correct answer: To speed up spatial queries by organizing feature locations
A spatial index (e.g., R-tree) organizes feature bounding boxes so the database can quickly locate features without scanning every record.
Question 6: Which of the following is an example of nominal (categorical) geospatial data?
- Elevation in meters
- Population count per county
- Land use classification (residential, commercial, industrial) (Correct answer)
- Average annual rainfall in inches
Correct answer: Land use classification (residential, commercial, industrial)
Nominal data assigns features to named categories without implying order or magnitude, such as land use types.
Question 7: What distinguishes 2.5D GIS data from true 3D GIS data?
- 2.5D stores a single Z value per X,Y location; true 3D allows multiple Z values at the same X,Y (Correct answer)
- 2.5D uses raster format; true 3D uses vector format
- 2.5D requires a projected CRS; true 3D requires a geographic CRS
- 2.5D is displayed in 2D only; true 3D requires VR hardware
Correct answer: 2.5D stores a single Z value per X,Y location; true 3D allows multiple Z values at the same X,Y
2.5D (also called '2.5-dimensional') assigns one elevation per planimetric location, while true 3D supports volumes and overhangs where multiple Z values exist at a single X,Y.
GIS Geospatial Data Fundamentals 2
Which data model represents geographic features as a continuous grid of cells, each with an assigned value?