I'm writing some software which can plot boundaries, similar to the resolution of the 'Coastline paradox'. I have aesthetic solutions for borders over land with variable lengths for straight runs, but was curious if there is some legal pretense or political convention which determines how precisely various types of boundaries (property, county, province, state, national, ...) are measured IRL.
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There are borders that run straight for hundreds of kilometers, others that twist each few metres.. youtube.com/watch?v=gtLxZiiuaXs So I would say there is no standard, maybe the people at geographicinformationsystems can provide more information.– SJuan76Commented Apr 10, 2016 at 2:59
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3I'm voting to close this question as off-topic because it belongs on the GIS stack exchange.– JasperCommented Apr 13, 2016 at 6:37
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1 Answer
Many boundaries are defined using:
- Latitude (in degrees, minutes, seconds) north or south of the equator
- Longitude (in degrees, minutes, seconds) east or west of a prime meridian (such as through the Greenwich Observatory)
- A reference geoid or ellipsoid (such as NAD 83), or the use of local surveying relative to mountains or stars.
Sometimes the boundary is clarified by using a map projection (that is based on a reference ellipsoid like NAD 83 and a UTM zone definition), with units in feet or meters relative to the origin of the zone. For example, the U.S. Supreme Court ratified such an ocean boundary (measured in meters, with a precision of 1 millimeter) between the United States and California. Most of the ruling is a data dump from a GIS system.
In many U.S. states, property boundaries are defined using chains of offsets. Each offset is measured in feet (often to a precision of 0.01 feet), with an angle in degrees, minutes, and seconds.
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1Some also use geographic features, for example the portion of the US-Mexico border that, per the 1848 Treaty of Guadalupe Hidalgo, follows the middle of the Rio Grande "along the deepest channel", and as such is in constant flux per the slowly changing nature of a river. Commented Apr 13, 2016 at 15:42
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@MichaelBroughton -- Correct. My answer focused on "units of measurement", because it seemed (to me) that the original poster was trying to choose the units for a GIS program.– JasperCommented Apr 13, 2016 at 18:33
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@Jasper I've never used GIS and am working on my own opengl app. I was mainly concerned with eliminating floating point numbers from my data. It's a little hard to explain, but boarders are described by sequential points, and as such take only a distance and angle as a parameter, and thus take less space when stored on disk (i8 or i16 instead of f32 or f64). Commented Apr 13, 2016 at 22:51
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@punkerplunk -- The program you are writing is a very specialized GIS app. GIS is short for Geographic Information System(s). You seem to be trying to compress the data using an integer-format polyline. That kind of programming hack is much more on-topic on one of the programming stack exchanges (possibly including GIS.SE) than on politics.SE.– JasperCommented Apr 14, 2016 at 5:20
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@Jasper My curiosity is not about my program, though. It's about more of a vague curiosity out how far is the lowest bound before even an official would consider a measure absurdly precise. Like so many of my questions, probably doesn't really belong anywhere, though. Anyway, I appreciate your answer very much. I find, indeed, 0.01 feet to be quite absurdly precise. I was unfamiliar with the term 'chain of offset' so thanks for that. Incidentally, I always assumed GIS was a specific program, used by college types, geologists and civil engineers and the like. Commented Apr 15, 2016 at 4:07