OpenStreetMap

Wrote Matlab code for plotting a boundary described by metes and bounds.

Posted by BaddDadd on 11 September 2020 in English (English)

Well, really just metes

Anyway, I had a description of the property, which can be hard to follow for most of us. Here’s an example description of part of Buttonbush Nature Area:

Commencing at the South ¼ corner of Section 10, T2S, R6E, City of Ann
Arbor, Washtenaw County, Michigan; thence N01°57’53”W 60.00 feet
along the North-South ¼ line of said Section 10 and along the East line of
Foxfire Condominium, Washtenaw County Condominium Subdivision Plan
No. 136 for a PLACE OF BEGINNING; thence continuing N01°57’53”W
2208.89 feet along said North-South ¼ line and along the East line of
Foxfire Condominium, Washtenaw County Condominium Subdivision Plan
No. 136 and along the East line of Fox Ridge Commons Condominium,
Washtenaw County Condominium Subdivision Plan No. 176; thence 96.56
feet along the arc of a 7442.41 foot radius circular curve to the right, chord
bearing N81°07’45”E 96.56 feet along the South right-of-way line of US-23
(variable width); thence S07°00’18”E 195.59 feet; thence S48°50’07”E
5.51 feet; thence S01°57’53”E 2022.40 feet; thence S88°16’54”W 117.07
feet along the proposed north right of way line of Dhu Varren Road (60
feet proposed half width) to the Place of Beginning, being a part of the
Southeast ¼ of said Section 10 and containing 5.90 acres of land, more or
less.

My eyes glazed over the first time I read that. But after looking at it for a while, I realized that i only needed a little bit of that to figure out the boundary. Most of it was just prose.

To get the data I needed, the first step was to eliminate all the prose, and put it in a standard form that could be more easily read in. I copied the text and just started deleting the extra words. This became:

# Commencing at the South 1/4 corner of Section 10, T2S, R6E,
# City of Ann Arbor, Washtenaw County, Michigan
# Containing 5.90 acres of land
N01,57,53,W 60.00 feet
PLACE OF BEGINNING
N01,57,53,W 2208.89 feet
Arc 7442.41 foot radius
N81,07,45,E 96.56 feet
S07,00,18,E 195.59 feet
S48,50,07,E 5.51 feet
S01,57,53,E 2022.40 feet
S88,16,54,W 117.07 feet
Place of Beginning

This is almost entirely just deleting unnecessary parts of the description. It’s easier to do that manually than to write a program that does it. What’s left is the description of the starting point in comments in the first couple lines, a pair of lines specifying the starting/ending corner of the boundary, and one additional line where the boundary is a circular arc rather than a straight line. I did change the degree, minute, and second symbols to commas [Edit: No longer necessary!], just so I didn’t have to search for each symbol separately. (Using spaces would also work.)

The comment lines at the top aren’t used. I kept the description of the starting location, and also moved the “Containing 5.90 acres” description there, because I like keeping that information.

When I read in the data, I look at the first character of each line to determine what the line is. N, S, A, P, and # are recognized, and a line beginning with any other character is ignored. N or S means that line is one part of the boundary, usually a straight line. A for Arc means the following line is a circular arc, and gives the radius of the circle. I report the maximum deviation from a straight line. P for Place of Beginning denotes the beginning/ending corner of the property boundary. Any lines prior to the first Place are just to get from a known reference location to a corner. The segments between the two Places should form a closed loop, with only a tiny error. If they don’t, something is wrong in the description, either in the source document, or in the process of converting it to the standard form.

I should add the caveat that I don’t know if the way the prose is written is fairly standard, or if it varies between jurisdictions. For example, Place of Beginning might be a different term elsewhere.

I’ll post the code in the following entry.

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