GISLayer

A GISLayer is an abstraction used in geographic information systems to manage a single set of geographic data for display and analysis. It can represent vector data, raster data, or other data sources. Each layer references its data source and carries metadata used by the map canvas and tools.

Vector layers store features defined by geometry and attribute data; raster layers store gridded values such as imagery or elevation. Some systems categorize layers by geometry type and data source.

Key properties include the coordinate reference system, spatial extent, visibility, opacity, and rendering information such as symbology and labeling. Layers may have scale-dependent visibility, time extent, and metadata.

Common operations include querying features, selecting, editing geometries and attributes, and conducting spatial analyses. Rendering uses styles to display features; labeling uses attribute fields. Layers can be derived, joined, or prepared for analysis.

Data formats and sources: vector formats like Shapefile, GeoJSON, GeoPackage; raster formats like GeoTIFF; database backends such as PostGIS. Layers can also be streams from remote services such as WMS or WMTS. In many frameworks, GISLayer is a base class with specialized subclasses for vector and raster data.