Which type of model is composed of a grid of cells, each with an attribute value?

A raster model is composed of a grid of cells, where each individual cell (or pixel) holds an attribute value that represents information about the specific area that the cell covers. This grid structure is particularly effective for representing continuous data, such as elevation, temperature, or vegetation density, where variations occur across a landscape.

This model format allows for the efficient processing and analysis of spatial data, as operations can be applied across all cells in a uniform manner. For instance, in the case of operations like overlays or surface analysis, the cell-based structure simplifies the computation of results based on the attributes of neighboring cells.

In contrast, a geodatabase is more of a storage structure for various data types, including both vector and raster data, and does not inherently utilize a grid format. Vector models consist of points, lines, and shapes to represent discrete features and their attributes; they do not use a grid of cells. Lastly, network models are specifically designed to represent interconnected systems, such as transportation networks, where the focus is on analyzing flow or connectivity rather than continuous spatial extents like those represented in raster models. Hence, identifying the right structure and functionality of raster data emphasizes why it is the correct choice.