Are there any scientific approaches for defining the smallest recognizable object? For example, a lake has a complex shape, and at a certain scale it is impossible to distinguish its characteristic features and so it doesn't makes sense to display on the map. How to define this scale?

  • Resolution is related more to the smallest distance between two (point) features that are distinguishable - if you consider just one feature, you can't have a definitive answer because you could still render a lake as a single point, if its existence and location are important part of the information that the map represents. Maybe there are specific rules for a specific types of maps (e.g. lakes on topographic maps), but those are probably chosen empirically rather than defined scientifically. – mkadunc Oct 18 '16 at 0:34
  • e.g. from OS mastermap (1:1250 scale): Buildings are defined as roofed constructions, usually with walls and being permanent. This includes permanent roofed-constructions that exceed 8.0 m2 in area (12.0 m2 in private gardens). Exceptions are made to this area rule for smaller buildings that, due to their detached position, form relatively important topographic features. These are shown at minimum size as stated above. ordnancesurvey.co.uk/docs/user-guides/… – mkadunc Oct 18 '16 at 0:58

There is a good article on ESRI Blog: On map scale and raster resolution which answers your question. I will quote the rule here:

The rule is: divide the denominator of the map scale by 1,000 to get the detectable size in meters. The resolution is one half of this amount.”

So here is the appropriate resolution for a select set of map scales, as mentioned in the article:

enter image description here


There is something the US developed long ago, primarily for intelligence images I think, called the National Image Interpretability Rating Scales (NIIRS). While scale is a major part of NIIRS, the 'Interpretability' was a somewhat subjective base upon whether the interpreter could see certain features in the image. For example, NIIRS 2 - can detect large aircraft hangars, NIIRS 3 - can identify wing configurations on aircraft, NIIRS 4 - can identify fighter plane by type, etc.

Maybe search engine around and see what NIIRS stuff is out there.

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