Karkeuskartta

Karkeuskartta, or roughness map, is a spatial representation of surface roughness or microtopographic variability. Typically produced as a raster layer, each cell contains a roughness value that reflects the texture of the terrain, built surfaces, or other features. Such maps are used to model processes sensitive to surface texture, including wind flow, infiltration, runoff, sediment transport, snow accumulation, and vegetation establishment.

The term is a compound of Finnish: karkeus meaning roughness and kartta meaning map. In Finnish GIS and geomorphology literature, karkeuskartta denotes maps that summarize surface irregularity in a geographical space, often as a relative index rather than an absolute physical measurement.

Roughness values can be derived from high-resolution elevation data (LiDAR, photogrammetry) or from existing digital elevation models. Common approaches compute a local roughness index, such as the standard deviation of elevation within a moving window, rugosity measures from 3D surface data, or other texture metrics that capture planimetric or vertical variability. The resulting products are gridded datasets with values calibrated to a chosen scale.

Applications span urban planning, wind energy, hydrology, geomorphology, forestry, and environmental risk assessment. Roughness maps assist in simulating wind speed near the ground, predicting drainage patterns, assessing soil erosion risk, and planning land use that accounts for surface texture.

Interpretation requires awareness of data quality, resolution, and the method used to compute roughness; different datasets or metrics can yield different results. Karkeuskartta is most informative when integrated with other geospatial layers such as land cover, elevation, or soil data.