OverlayAnalysen

OverlayAnalysen refers to a family of analytical methods used to examine the effects and relationships that emerge when multiple data layers are combined spatially or thematically. Rooted in geographic information systems (GIS), overlay analysis enables researchers and planners to synthesize attributes from different sources to produce new insights, such as where a suitable site meets environmental constraints or where risk factors converge.

Two main classes are raster overlays and vector overlays. Raster overlays operate at the cell level and use map algebra to combine cell values according to arithmetic or logical rules, producing a new raster that reflects the integrated information. Vector overlays perform geometric operations on polygon, line, and point features, yielding new features with combined geometries and attributes; common operations include Union, Intersect, Identity, Clip and Difference.

Workflow and requirements: overlay analysis relies on compatible coordinate reference systems and appropriate data resolutions. Preprocessing steps include cleaning attributes, aligning extents, resolving topology, and handling missing data. The output is typically a derived layer—such as a suitability map, hazard map, or resource availability map—and a set of statistics or a metadata record.

Applications include environmental planning, urban design, natural hazard assessment, public health, and resource management. Overlay analyses support multi-criteria decision making by combining quantitative indicators with qualitative observations.

Limitations include dependence on data quality and scale; mismatches in resolution or conceptual meaning across layers can bias conclusions; the approach can be computationally intensive for large datasets; and uncertainty propagation is an important consideration.