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What is a raster resolution?
The spatial resolution of a raster refers to the size of the cells in a raster dataset and the ratio of screen pixels to image pixels at the current map scale. For example, one screen pixel can be the result of nine image pixels resampled into one—a raster resolution of 1:9.
What is raster extent?
The spatial extent of a raster, represents the “X, Y” coordinates of the corners of the raster in geographic space. This information, in addition to the cell size or spatial resolution, tells the program how to place or render each pixel in 2 dimensional space.
Why are rasters resampled to a common resolution?
When performing analysis between rasters of different cell sizes, the rasters are resampled to a common resolution, typically to the coarsest unless otherwise specified, before performing the function. The major disadvantage of cell representation of map data is the loss of resolution that accompanies restructuring data to fixed cell boundaries.
How big does a raster surface need to be?
The cell must be small enough to capture the required detail but large enough so computer storage and analysis can be efficient. The more homogeneous an area is for critical variables, such as topography and land use, the larger the cell size can be without affecting accuracy.
The higher the resolution of a raster, the smaller the cell size and, thus, the greater the detail. This is the opposite of scale. The smaller the scale, the less detail shown. For example, an orthophotograph displayed at a scale of 1:2,000 shows more details (appears zoomed in) than one displayed at a scale of 1:24,000 (appears zoomed out).
What do you mean by spatial resolution in GIS?
In a GIS, you are most often concerned with the spatial resolution of a raster dataset, especially when displaying or comparing raster data with other data types, such as vector. In this case, resolution refers to the cell size (the area covered on the ground and represented by a single cell). A higher spatial resolution implies