GSI Viewer

GSI Viewer enables fast, browser-based exploration of geospatial datasets by rendering multiple data sources in a common viewport. It supports raster and vector sources, coordinate systems, and tile-based rendering to facilitate layer comparison and coordinate validation. Conceptually, the tool maintains a configurable viewport with a set of enabled layers, then requests map tiles or vector tiles and composes them into a single view. This approach lets GIS professionals verify alignment, probe data coverage, and assess compatibility between sources. Use cases include urban planning reviews, environmental assessments, and field-data validation where quick visualization is more important than heavy analysis. Core features include layer management, projection support, tile fetching, and viewport export. The tool differentiates itself through lightweight, dependency-free rendering, rapid data source switching, and export options for reproducible results. Typical workflows involve specifying a center coordinate, setting a zoom level, selecting layers, and observing how layers align across basemaps. Outputs include a portable viewport descriptor and optional exports, enabling downstream processing in other GIS systems. The tool emphasizes standards conformance (EPSG:4326/3857), interoperability with WMS/WMTS, and efficient data handling for large datasets. Beneficiaries are analysts, planners, researchers, and developers who need quick, repeatable geospatial views without installing software or managing heavy servers. The unique value lies in its balance of simplicity and capability: reliable tiling, straightforward coordinate handling, and export-ready results suitable for documentation or integration into automated workflows.