

Can You Interpret These Land Survey Numbers?
08252019, 04:15 PM

#1

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Can You Interpret These Land Survey Numbers?
Here are two pages from a survey. Each line of numbers apparently refers to the numbered location on the chart, and seems related to the marker CP101, which I have located.
Does anyone know what these numbers mean? Is there any way to find a given location based on those numbers?
Thanks.
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Al




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08252019, 05:30 PM

#2

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My guess is that they are parameters for Bezier curves.
https://en.wikipedia.org/wiki/B%C3%A9zier_curve
That's all I got.
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08252019, 05:50 PM

#3

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I'd sure hate to pay for a survey and get it back without a map and numbers on it. Unless they're understood, they're worthless.



08252019, 06:09 PM

#4

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Quote:
Originally Posted by Bamaman
I'd sure hate to pay for a survey and get it back without a map and numbers on it. Unless they're understood, they're worthless.

1. Do survey. Charge money.
2. Interpret survey results. Charge money.
3. Profit!
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08252019, 06:17 PM

#5

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Sure looks like latlong for each point.



08252019, 06:26 PM

#6

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My best guess is that these are cartesian coordinates. Units? I'm not sure if feet, yards meters or? I would further guess that CP101 is point 18 on your map. Units can be inferred by finding other iron lot markers and comparing to the chart provided.



08252019, 06:33 PM

#7

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The table looks like a list of the coordinates of the points on the map. The first column is the point number. The second column looks like the northing, and the second column is easting. For example, point 1 has a northing of 2872.8 and point 2 has a northing of 2972.2. That means that point 2 is about 100feet north of point 1.



08252019, 06:40 PM

#8

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Quote:
Originally Posted by MikeWillRetire
The table looks like a list of the coordinates of the points on the map. The first column is the point number. The second column looks like the northing, and the second column is easting. For example, point 1 has a northing of 2872.8 and point 2 has a northing of 2972.2. That means that point 2 is about 100feet north of point 1.

^This is it. Most likely in feet. And they are based on an arbitrary coordinate base. Not latitude or longitude. Disregard the 4th column. It is for elevation, but your surveyor didn't do elevations. So the data in column 4 is null. The 5th column is just the description of the point.
Distance between any 2 points is ((N1N2)^2+(E1E2)^2)^.5. Where N is the north coordinate, and E is the east coordinate. Just subtract the north coordinate from another northing. Square that. Do the same for the eastings. Add the difference in the northings squared to the difference in the eastings squared, and then take the square root. This will give you the distance between the coordinate points. Based on the Pythagorean Theorem.
For example, the difference in the northings of 8 to 2 is 2988.2256 (northing of 8) minus 2972.2426 (northing of 2) is 15.983'. Easting difference is 4495.46024644.6062 or 149.146. Square the northing difference of 15.983 is 255.46. Square the easting difference of 149.146 is 22244.53. Add 22244.53 and 255.46 to get 22499.99. Take the square root of that to get 150.00' between points 2 and 8.
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08252019, 08:21 PM

#9

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Quote:
Originally Posted by Ronstar
^This is it. Most likely in feet. And they are based on an arbitrary coordinate base. Not latitude or longitude. Disregard the 4th column. It is for elevation, but your surveyor didn't do elevations. So the data in column 4 is null. The 5th column is just the description of the point.
Distance between any 2 points is ((N1N2)^2+(E1E2)^2)^.5. Where N is the north coordinate, and E is the east coordinate. Just subtract the north coordinate from another northing. Square that. Do the same for the eastings. Add the difference in the northings squared to the difference in the eastings squared, and then take the square root. This will give you the distance between the coordinate points. Based on the Pythagorean Theorem.
For example, the difference in the northings of 8 to 2 is 2988.2256 (northing of 8) minus 2972.2426 (northing of 2) is 15.983'. Easting difference is 4495.46024644.6062 or 149.146. Square the northing difference of 15.983 is 255.46. Square the easting difference of 149.146 is 22244.53. Add 22244.53 and 255.46 to get 22499.99. Take the square root of that to get 150.00' between points 2 and 8.

This is spot on. Survey worksheet with a coordinate list.



08262019, 03:15 PM

#10

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Thanks.
Something doesn't add up. The numbers say that point 17 is 13 feet north of Point 18 (and about the same amount north of CP101). But it can't be more than a few feet.
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08262019, 03:21 PM

#11

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Quote:
Originally Posted by Ronstar
^This is it. Most likely in feet. And they are based on an arbitrary coordinate base. Not latitude or longitude. Disregard the 4th column. It is for elevation, but your surveyor didn't do elevations. So the data in column 4 is null. The 5th column is just the description of the point.
Distance between any 2 points is ((N1N2)^2+(E1E2)^2)^.5. Where N is the north coordinate, and E is the east coordinate. Just subtract the north coordinate from another northing. Square that. Do the same for the eastings. Add the difference in the northings squared to the difference in the eastings squared, and then take the square root. This will give you the distance between the coordinate points. Based on the Pythagorean Theorem.
For example, the difference in the northings of 8 to 2 is 2988.2256 (northing of 8) minus 2972.2426 (northing of 2) is 15.983'. Easting difference is 4495.46024644.6062 or 149.146. Square the northing difference of 15.983 is 255.46. Square the easting difference of 149.146 is 22244.53. Add 22244.53 and 255.46 to get 22499.99. Take the square root of that to get 150.00' between points 2 and 8.

I think I recall doing this in 3rd grade...right after learning cursive.
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08262019, 04:19 PM

#12

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Quote:
Originally Posted by TromboneAl
.....But it can't be more than a few feet.

I assume you found survey stakes about a few feet apart. And you think that those points are 17 and 18. They probably are not. One may be cp #101. Are something else. Usually when the survey point list has “calc” in the last field for a description, that means that there is no stake at that coordinate point  it’s a calculated point that the surveyor calculated based on dimensions on the subdivision plat.
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08262019, 06:06 PM

#13

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Quote:
Originally Posted by target2019
Sure looks like latlong for each point.

That's what I thought at first, but it would put it in the middle of the Atlantic Ocean. Or if they're really both positive numbers, probably Saudi Arabia.
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08262019, 06:11 PM

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Al, I think you need to find the index diagram for your town or county's plat or master index. I think it's something like the "index" part of this tutorial for searching historical land records: https://www.blm.gov/or/landrecords/f...structions.pdf
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08262019, 06:34 PM

#15

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Ronstar,
I found your expertise with surveying quite amusing after noting your location description
LOL
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08262019, 07:26 PM

#16

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Quote:
Originally Posted by Ronstar
I assume you found survey stakes about a few feet apart. And you think that those points are 17 and 18. They probably are not. One may be cp #101. Are something else. Usually when the survey point list has “calc” in the last field for a description, that means that there is no stake at that coordinate point  it’s a calculated point that the surveyor calculated based on dimensions on the subdivision plat.

Well, there are no stakes. I'm just looking at the diagram.
That CP#101 looks very official, and is a few feet from the edge of the road.
If 17 was 13' north of that, it would past the midpoint of that driveway.
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Can You Interpret These Land Survey Numbers?
08262019, 07:46 PM

#17

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Can You Interpret These Land Survey Numbers?
You really can’t do much analysis with the diagram if you don’t have the coordinates of cp 101. CP101 is not a lot corner, it’s only a temporary survey point used to measure to other points. I don’t see how you figure that 17 is 13’ north of cp101 if you don’t have coordinates of 101. Don’t confuse 18 with 101. Even though they look close on the diagram, you really need the coordinates of 101 before analyzing this with any kind of precision. And it would help to know for certain that the nail in your photo is 101. Maybe there’s another nail in the area.
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08262019, 11:36 PM

#18

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Yes, the pairs of numbers are Cartesian coordinates, and the unit of measurement is in feet because if in meters the lots would be quite large.
I wonder if the northing and easting are arbitrary or if they are based on a transverse Mercator projection such as used in the UTM (Universal Transverse Mercator) map system and the MGRS (Military Grid Reference System) by the military. In the UTM and MGRS systems, the northing and easting coordinates are not arbitrary, but rather an absolute Cartesian XY coordinate pair that corresponds to a particular latitude/longitude pair.
I have read that in the civilian sector, states or counties have their own State Plane Coordinate Systems. If the numbers that TAl has are in such a coordinate system, then the "arbitrary axis system" is not something that the surveyor made up, but is already defined by the local government. Then, there is certainly a way to reference to a local datum in the area, which defines the origin of this "arbitrary coordinate".
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08272019, 04:57 AM

#19

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^ the coordinates in the list could be from a defined regional coordinate system (state plane, utm) but the list shows truncated values if they are from a defined system. There would be negative coordinates about a half mile away if they were true defined coordinates. That doesn't happen. Usually coordinates from a defined regional system have values in hundreds of thousands or millions of feet so as to not have negative coordinates within the area covered by the coordinate system.
They could be based on a local datum, but even then there would be negative coordinates about a half mile away. Not likely. IMO, the coordinates are either truncated values from a local or regional mapping system, or are from an arbitrary system.
The survey drawing and coordinate list shown is not something that is usually given to a property owner. It is for the surveyor's own use  a record of how he/she did their survey  just for their files
Normally the lot corners are staked and a drawing (plat) is made and given to the client. If Al hired the surveyor, I recommend that he ask for a Plat of Survey. Or at least ask the surveyor how he can figure out where the lot corners are based on the diagram and coordinates that were provided.
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08272019, 08:46 PM

#20

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Quote:
Originally Posted by Ronstar
... They could be based on a local datum, but even then there would be negative coordinates about a half mile away. Not likely. IMO, the coordinates are either truncated values from a local or regional mapping system, or are from an arbitrary system.
The survey drawing and coordinate list shown is not something that is usually given to a property owner. It is for the surveyor's own use  a record of how he/she did their survey  just for their files

Yes, usually a bias value is added to the mathematical projected northing and easting so that the coordinates are always positive. And yes, truncation of a very large coordinate number would make sense if it does not cause confusion when the leading digit overflows into the higher significant digit to the left.
I don't know about the customs used by surveyors, but the coordinate specification to the 0.0001 ft is peculiar. That's 1.2 mil (1/1000 of an inch)! For comparison, a piece of paper is usually about 4 mil thick.
Obviously, no surveyor can measure anything down to less than a paper thickness. It would be most likely that these numbers are the results of a calculation to convert from something else, such as geodetic latitude and longitude, into this "unknown" coordinate system. And a computer can carry out any formula to an arbitrary very fine resolution, even though the inputs entered to the formula are not that precisely known.
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