GIS Conceptual Foundations 2 — Questions and Answers
Question 1: Which concept describes the minimum unit of geographic space that a GIS can represent?
- Resolution
- Extent
- Scale
- Grain (Correct answer)
Correct answer: Grain
Grain refers to the smallest distinguishable unit in a spatial dataset, analogous to pixel size in raster data.
Question 2: What does the term 'spatial autocorrelation' mean in GIS?
- Features repeat across time
- Nearby locations tend to have similar attribute values (Correct answer)
- Coordinates are automatically corrected
- Layers are aligned to the same projection
Correct answer: Nearby locations tend to have similar attribute values
Spatial autocorrelation, described by Tobler's First Law, states that nearby things are more related than distant things.
Question 3: A GIS analyst needs to represent continuous phenomena like elevation. Which data model is most appropriate?
- Network
- Vector polygon
- Raster (Correct answer)
- TIN only
Correct answer: Raster
Raster data models store continuous surface values in a grid of cells, making them ideal for elevation, temperature, and similar phenomena.
Question 4: What is the primary purpose of a spatial index in a GIS database?
- To store attribute data alphabetically
- To accelerate spatial queries by organizing features by location (Correct answer)
- To reproject data between coordinate systems
- To validate topology rules
Correct answer: To accelerate spatial queries by organizing features by location
Spatial indexes (e.g., R-trees, quadtrees) organize geometries so the database can quickly find features within a query area without scanning every record.
Question 5: Which statement best describes 'scale' in the context of GIS?
- The number of attributes per feature
- The ratio of map distance to real-world distance (Correct answer)
- The coordinate system used for projection
- The file format of the spatial data
Correct answer: The ratio of map distance to real-world distance
Map scale is the ratio between a distance on the map and the corresponding distance on the Earth's surface.
Question 6: In GIS, what is an 'attribute table'?
- A legend explaining map symbology
- A tabular database storing non-spatial properties of geographic features (Correct answer)
- A list of coordinate reference systems
- A metadata record for a spatial file
Correct answer: A tabular database storing non-spatial properties of geographic features
An attribute table stores descriptive, non-spatial information about geographic features, linked to their geometries by a unique identifier.
Question 7: What distinguishes a geodatabase from a shapefile?
- Shapefiles support topology rules; geodatabases do not
- A geodatabase can store multiple feature classes, relationships, and topology in one container (Correct answer)
- Shapefiles are binary; geodatabases are plain text
- A geodatabase cannot store raster data
Correct answer: A geodatabase can store multiple feature classes, relationships, and topology in one container
A geodatabase is a relational database container that supports multiple feature classes, relationship classes, topology, and raster datasets, unlike a shapefile's single-feature-class structure.
GIS Conceptual Foundations 2
Which concept describes the minimum unit of geographic space that a GIS can represent?