Not all questions with that tag refer to raster data though that does seem to be the most common thread. Perhaps the Wiki should just be edited to something like 'the granualarity of data samples' or 'the smallest distinguishable unit of measure in data' (expanded on both counts). I'm just wondering if generalizing the existing tag definition would be better than creating additional more specific tags. And whether current or potential future frequency of application of those tags would warrant their creation or reservation now.
I do note a map-resolution tag (x9) that seems fairly synonymous - in fact both are applied to about half the questions.
So I would propose that map-resolution be made synonym of resolution, and the Wiki of that be changed to something like:
Resolution is a measure of the smallest unit or sample in data that
can be distinguished from any other, and/or the number of samples for a
In GIS this often refers to spatial or ground
resolution of raster cells or pixels. For example SRTM data can be
available at resolutions of 90m or 30m, where one cell with a single, constant
elevation value is assigned to a square on the ground 90m or 30m on a
side. Satellite imagery is often discussed in terms of resolution, where one image pixel represents 0.5m (high), 15m (mid), or 30m (low). Descriptors such as 'high' and 'low' are somewhat arbitrary, but demonstrate resolution values have a range or spectrum similar to map scales ('large' and 'small').
However resolution also applies to the values measured for that ground
distance. In the case of SRTM there is also a vertical resolution
since that data measures elevation. Contour lines can easily
demonstrate this - each line in the data may represent a difference of
1m, 5m, or 100m. Other resolution type examples include spectral
(width on the EM spectrum covered by a single band), temporal (time
between samples - minutes, days, or years), or radiometric (the
strength or magnitude of a signal).
Note that resolution applies to vector data as well as raster or
value. The same section of sinuous river could be represented with a
dozen points or a hundred. The more samples along the line, the more
detail or resolution with which that feature can be represented in the
With the first sentence being the Wiki excerpt as well.