What does the following sentence mean, especially "in extent"

Two final reasons for a feature-based approach arise from its inherent discretization of the environment. First, Features are localized in extent, and feature size can be matched to sensor footprint.

I know the meaning of extent but I'm not able to comprehend its meaning in the aforementioned sentence. Features here mean landmarks or physical objects in the field of mapping and navigation (e.g. a tree).

  • What is the source of your example?
    – user3169
    Jul 26, 2015 at 22:56
  • @user3169, what do you mean? Do you want the actual paper?
    – CroCo
    Jul 26, 2015 at 22:59
  • 1
    If the example sentence came from a document or online source, you should credit it or add a link to it. In any case, I think a couple of sentences before and after might help with understanding the context of usage. I wonder if it is technical in nature.
    – user3169
    Jul 26, 2015 at 23:08
  • 2
    @CroCo: You can still give a citation (author, title, journal where published, date, etc). Please do. Jul 27, 2015 at 0:58
  • This is the link marinerobotics.mit.edu/sites/default/files/Smith97oceans.pdf. It seems accessible from this website.
    – CroCo
    Jul 27, 2015 at 17:39

1 Answer 1


Extent means "the area covered by something".

Localized means "restricted to a particular place".

So "Features are localized in extent" says "The areas covered by features are restricted to particular places". In other words, a feature exists within a specific geographical area, and does not extend outside that area.

The construction "X is Y in Z" is often used to say that a particular attribute Z of an object X can be described as Y. A simpler example would be "My car is blue in color".

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