GISP - Geographic Information Systems Professional Spatial Analytical Methods Questions and Answers — Questions and Answers
Question 1: An environmental agency needs to identify the most suitable locations for a new wildlife preserve. They have several raster layers representing different criteria: proximity to water, land cover type, slope, and distance from existing roads. Each criterion has a different level of importance for the final decision. Which spatial analysis technique is most appropriate for combining these raster layers to create a final suitability map?
- Zonal Statistics
- Weighted Overlay (Correct answer)
- Inverse Distance Weighting (IDW)
- Network Analysis
Correct answer: Weighted Overlay
Weighted Overlay is a multi-criteria evaluation technique used to combine multiple raster datasets. It allows the analyst to reclassify values to a common scale and assign different weights to each input layer based on its importance, creating an integrated suitability model.
Question 2: A crime analyst is studying the spatial distribution of burglaries and wants to determine if the incidents, when considering their locations and attributes (e.g., value of stolen goods), are statistically clustered, dispersed, or randomly distributed across the entire city. Which statistical measure is specifically designed to evaluate this type of global spatial autocorrelation?
- Standard Deviational Ellipse
- Moran's I (Correct answer)
- Getis-Ord Gi*
- Mean Center
Correct answer: Moran's I
Moran's I is a global statistic that measures spatial autocorrelation. It produces a single value that indicates whether the overall pattern of feature values is clustered, dispersed, or random across the study area. Getis-Ord Gi* is a local statistic used to identify the location of specific hot spots and cold spots, not to describe the overall global pattern.
Question 3: A fire department needs to create a map showing all areas that can be reached by a fire engine from a specific station within a 5-minute drive time, accounting for road speeds and turn restrictions. Which type of network analysis is most effective for creating this 'response zone' polygon?
- Shortest Path Analysis
- Location-Allocation Analysis
- Service Area Analysis (Correct answer)
- Traveling Salesperson Problem (TSP)
Correct answer: Service Area Analysis
Service Area Analysis is used to find a region that encompasses all accessible streets within a specified impedance (e.g., a 5-minute drive time). The output is typically a polygon representing the reachable area, which is exactly what is needed for a response zone.
Question 4: Which of the following spatial interpolation methods is considered an 'exact' interpolator, meaning the resulting surface passes directly through all the input sample points, and calculates unknown values based on a weighted average where the influence of a sample point diminishes with distance?
- Kriging
- Spline
- Inverse Distance Weighting (IDW) (Correct answer)
- Trend Surface Analysis
Correct answer: Inverse Distance Weighting (IDW)
Inverse Distance Weighting (IDW) is a deterministic and exact interpolator. It assumes that the influence of a sample point decreases with distance. Because a sample point has a distance of zero from itself, it receives all the weight in the calculation, ensuring the interpolated surface honors the known data points precisely.
Question 5: A GIS analyst has a polygon layer of soil types and another polygon layer of land use zoning. To support a detailed environmental assessment, they need to create a new layer where the output polygons represent every unique combination of soil and zoning, and the attribute table contains the fields from both input layers. Which vector overlay operation should be used?
- Union (Correct answer)
- Erase
- Clip
- Buffer
Correct answer: Union
The Union operation computes the geometric intersection of two polygon layers, but preserves all features and attributes from both inputs. The output contains all polygons from both layers, split where they overlap, and the resulting polygons inherit attributes from both original layers.
Question 6: A developer plans to build a new cell phone tower on a hill and needs to create a map identifying all locations on the surrounding terrain from which the top of the tower will be visible. Given a high-resolution Digital Elevation Model (DEM), what type of terrain analysis is specifically designed to model this line-of-sight problem?
- Slope Analysis
- Watershed Delineation
- Viewshed Analysis (Correct answer)
- Cost Path Analysis
Correct answer: Viewshed Analysis
Viewshed analysis uses a DEM to determine the visibility from one or more observation points. It calculates a line of sight from the observer (the cell tower) to every other cell in the raster, producing an output that shows all visible areas.
GISP - Geographic Information Systems Professional Spatial Analytical Methods Questions and Answers
An environmental agency needs to identify the most suitable locations for a new wildlife preserve.
They have several raster layers representing different criteria: proximity to water, land cover type, slope, and distance from existing roads.
Each criterion has a different level of importance for the final decision.
Which spatial analysis technique is most appropriate for combining these raster layers to create a final suitability map?