Georeferenssi

Georeferenssi, in Finnish, translates to georeferencing in English. It is the process of assigning geographic coordinates to a map, image, or other spatial data. This means linking the data to a specific location on Earth. Without georeferencing, a digital map or image is just a collection of pixels without any real-world context. Georeferencing allows this data to be integrated with other geographic information systems (GIS) and used for spatial analysis and location-based services.

The process typically involves identifying known points on the source data and matching them to their corresponding coordinates in a standard geographic coordinate system, such as latitude and longitude or projected coordinates. These known points are called ground control points (GCPs). The more GCPs used and the more accurate they are, the better the georeferencing will be. Once the GCPs are established, a transformation is calculated to warp the source data so that its features align with their real-world positions.

Georeferencing is crucial for a wide range of applications. For example, historical maps can be georeferenced to be overlaid with modern maps, allowing for historical landscape change analysis. Satellite imagery and aerial photographs are almost always georeferenced to be used in mapping, environmental monitoring, and urban planning. Even scanned paper maps need to be georeferenced before they can be utilized in digital GIS environments. The accuracy of georeferencing directly impacts the reliability of any subsequent analysis performed on the data.