Reprojeksjonsfeil

Reprojeksjonsfeil, also known as projection error, refers to the inaccuracies that arise when transforming geographical data from one coordinate reference system to another. This process, called reprojection, is essential for displaying or analyzing data in a consistent format, especially when data originates from different sources or is intended for different mapping purposes.

The errors occur because coordinate reference systems are based on different mathematical models of the Earth's shape, called datums, and employ different methods for projecting the curved Earth's surface onto a flat map. These differences, such as variations in shape, area, distance, or direction, cannot be perfectly reconciled. When reprojection occurs, some degree of distortion is inevitable, affecting the spatial relationships of the original data.

Common causes of reprojection errors include using incompatible datums, employing different projection methods without appropriate transformations, or insufficient accuracy in the source data itself. These errors can manifest as shifts in position, changes in apparent shape or size of features, and distortions in distances or angles.

In geographic information systems (GIS), understanding and managing reprojection errors is crucial for accurate spatial analysis and decision-making. Techniques to minimize these errors involve selecting appropriate coordinate reference systems for the intended application, using high-quality transformation methods, and being aware of the inherent limitations of any projection. The magnitude of the error depends on the geographical extent of the area, the specific datums and projections involved, and the precision of the transformation parameters.