Untitled Flashcards Set

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.