Weighted Overlay
Definition
A GIS operation that combines multiple raster layers into a single output by multiplying each layer by a weight and summing the result. Used to produce probability or suitability surfaces from multiple contributing variables.
- Field
- GIS spatial analysis
- Operation
- Multiplies each raster layer by a weight, then sums
- Output
- Probability or suitability surface
- Input
- Multiple contributing raster variables
Common questions
How are the weights chosen in a weighted overlay for a search-probability map?+
Weights are typically assigned by expert judgement or statistical analysis of past case data, reflecting how strongly each variable, such as terrain slope, distance from a road, or vegetation cover, correlates with likely subject location.
What is a limitation of weighted overlay for search planning?+
The output is only as reliable as the input layers and the assigned weights; poor-quality data or weights based on a mismatched case type can produce a probability surface that misdirects search resources.
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