Untitled Flashcards Set

Raster: A spatial data model representing geographic phenomena as a grid of equally sized cells, each with an attribute value.

Pixel (Cell): The smallest unit in a raster grid, storing a single value for the area it represents.

Local Operation: Raster calculation where each output cell value is computed solely from the corresponding input cell(s).

Focal Operation: Also called neighborhood analysis; computes output cell values based on a function applied to a surrounding window of input cells.

Zonal Operation: Aggregates or summarizes input cell values within zones defined by another layer, producing statistics per zone.

Global Operation: Computes output values using information from all cells in the raster (e.g., viewshed, hillshade, distance).

Overlay: The process of combining two or more raster layers cell-by-cell, often using Boolean or arithmetic operators.

Reclassification: Assigning new values to cells based on their original values, typically to group or simplify categories (e.g., land-cover types).

Slope: A global derivative of elevation, measuring the rate of change (steepness) of elevation across neighboring cells.

Aspect: The compass direction that a slope faces, derived from the relative elevation of neighboring cells.

Viewshed: A global analysis identifying which cells are visible from a specified observer location based on elevation.

Hillshade: A shaded relief representation of terrain created by simulating illumination of the surface from a light source at a specified angle and altitude.

Focal Variety: A focal statistic that counts the number of unique cell values within a defined neighborhood around each cell.

Distance: A global or local analysis calculating the Euclidean distance from each cell to the nearest cell meeting a specified condition (e.g., water presence).