Untitled Flashcards Set

Key Vocabulary

• DEM (Digital Elevation Model): A raster representation of continuous surface elevations, where each cell’s value indicates height above a datum.

• Spatial Resolution: The ground distance between raster cell centers; higher resolution means smaller cells and finer detail.

• Bit Depth: The number of bits used to store each cell’s value; affects range and precision (integer vs. floating point).

• Mosaic: A raster operation that merges multiple rasters into one seamless dataset, requiring matching bands and bit depth.

• NoData: A special value indicating absence of data in a raster cell, often ignored during analysis.

• Contour Line: A vector representation derived from a DEM, connecting points of equal elevation.

• Slope (DEM‑derived): A raster of gradient values computed from elevation differences in a neighborhood around each cell.

• Aspect: A raster showing the compass direction (bearing) that each cell’s slope faces.

• Hillshade: A shaded relief raster simulating illumination of terrain from a specified sun angle and altitude.

• Viewshed: A raster identifying which cells are visible from one or more observer locations, considering intervening terrain.

• Local Function: Raster computation performed on each cell individually, without reference to neighbors.

• Neighborhood (Focal) Function: Raster computation based on a moving window around each cell, producing statistics like mean or variety.

• Zonal Function: Raster computation summarizing values within user‑defined zones, yielding statistics per zone.

• Global Function: Raster computation that considers the entire dataset for each output cell (e.g., viewshed, hillshade).

• Compression Quality: A parameter controlling the trade‑off between file size and data fidelity when storing rasters.