NAC is a geocode system for identifying an object anywhere on the Earth.

I am going to assign a unique NAC address for each building in Detroit. But different NAC addressed can be assigned to each building, because the building is an area with a different range of latitude and longitude and so it can be assigned a range of NAC, not just a unique one.

Does any one knows how can I choose a single unique NAC for a building?

Or what software I can use to assign NAC addresses to buildings?

I have read somewhere that you can assign the NAC of the centroid of a building as a NAC of that building. But I do not know how much this is true.

(You can see a house here with different NAC addresses)

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  • @PolyGeo Thanks a lot. I do not have any Idea what software to use and which strategy to choose. This is the issue that I have to solve.
    – elaheh
    Jun 2, 2014 at 10:13
  • So, there are some buildings in Detroit that do not already have a NAC assigned to them?
    – artwork21
    Jun 2, 2014 at 12:03
  • @artwork21, all building can be assigned NAC address easily according to their latitude and longitude, but it is not unique.
    – elaheh
    Jun 2, 2014 at 12:10
  • @martin f it was you can assign the NAC of the centroid of a building as a NAC of that building
    – elaheh
    Jun 3, 2014 at 4:30

1 Answer 1


You appear to be asking two very different questions.

First there is the issue of 'assign it where', as in what software or data are you working with? Is it a building layer that has no NAC attribute and you want to add? Is it a building layer that has two labels already and you want one? Are you creating it from scratch? Is it point labels on a map? What are you doing with this information? Without significantly more information we cannot make any software recommendations or answers.

It's possible there are geocoding locator services that can assign NAC addresses but I don't know, nor do I know what softwares they would be compatible with. A quick Google search on 'NAC locator' found this page. I also note an External Link at the bottom of the Wiki article leads to this page, which lists mapping services, software, and data for working with NAC.

Second, you appear to have an aribitrary rule problem in choosing an NAC address to use. The one with the majority of the building? Majority of the lot? Center of the building? That the building is accessed from? The front door? From the Wiki link now in your question:

An eight-character NAC specifies an area no larger than 25 metres by 50 metres, while a ten-character NAC cell is no larger than 0.8 metres by 1.6 metres.

So if your building is larger than the smaller cell, perhaps you would want to use an 8 instead of 10 character address. This part of your question is the equivalent of 'how many decimal places in a lat/lon coordinate should I use?' The NAC system of using cell addresses means that sometimes a feature will fall in more than one cell (or not completely cover a cell), and you must decide the rules on how to resolve that.

This is fundamentally similar to the issue in a raster representation of data - if a feature falls only partially in a cell, how do you define the value for that cell? You have to make a rule. For example the feature is really important, so whatever it touches is going to be that value; alternatively if it covers half the cell count it as the feature, otherwise don't. Both approaches are valid, you just need to create a justifiable rule and apply it consistently.

  • (+1) This is a good analysis, but I would encourage you to reconsider the final statement. The reason this problem is not fundamentally raster in nature is that buildings can have widely varying extents, unlike the cells of a raster.
    – whuber
    Jun 2, 2014 at 22:29
  • 1
    @whuber Yes, but that was my point - perhaps I have misphrased or was just unclear in my meaning. The NAC addressing system, based on the Wiki entry there, divides everything up into cells - essentially a raster data represenation even if it isn't actually in raster format. The problem with a raster representation is how do you represent irregular features that do not line up to a grid in a regular cell structure, hence my statement.
    – Chris W
    Jun 2, 2014 at 22:42
  • I see. The distinction I am making, which I believe is conventional, is that a raster is a regular division into cells. NAC, as it is discussed here, is much closer to an irregular or adaptive division--it's essentially a quadtree structure.
    – whuber
    Jun 2, 2014 at 22:45
  • @whuber Ah, I think understand the distinction, and recognize we're applying a grid to the globe. I was viewing it from the standpoint of a uniformly applied division level of the quadtree at those two resolutions (and maybe I'm not fully understanding NAC). I'm not really sure how to rephrase my over-simplification though, so feel free to edit if there's a better way to get the concept across.
    – Chris W
    Jun 2, 2014 at 23:47
  • Maybe you could simply replace "a raster representation" with "a raster/quadtree representation". I don't think we need to get too picky; you're talking a general concept.
    – Martin F
    Jun 3, 2014 at 18:59

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