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How do you identify an unknown coordinate system?

29 REPLIES 29
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Message 1 of 30
Anonymous
4008 Views, 29 Replies

How do you identify an unknown coordinate system?

I have to identify a point on my drawing.  My drawing is in US Survey Foot, Saint Louis County Transverse Mercator 96. 

In that coordinate system I have a point Northing of 3594314.418, Easting of 4658283.683.... the unknown coordinate system for that same point is x= 2,059,371.27 and y= 355,911.69.    I'm trying to figure out the northing easting point in US Survey Foot, Saint Louis County Transverse Mercator for x= 2,058,119.17 and y= 355,921.19.

 

Can anyone figure that out? 🙂

 

 

29 REPLIES 29
Message 21 of 30
Neilw_05
in reply to: Anonymous

Are you sure the mystery coordinates are in a defined projection? How do you know?

Neil Wilson (a.k.a. neilw)
AEC Collection/C3D 2024, LDT 2004, Power Civil v8i SS1
WIN 10 64 PRO

http://www.sec-landmgt.com
Message 22 of 30
Anonymous
in reply to: Neilw_05

@Neilw_05   the mystery point came from a PDF from the MnDot website and the points that aren't matching also came from MnDot and the other came from St.Louis County.  

Message 23 of 30
ChicagoLooper
in reply to: Anonymous

Thank you so much for posting the aerial picture and survey. I appreciate it. It has cleared everything up for me. I hope I can now clear everything up for you.

 

For the 3 pairs of coordinates you provided in your original post, only the second and last pair are relevant. The first pair doesn't do anything to solve this grand riddle, What is the Mysterious coordinate system. The coordinate system you are looking for is MN-N NAD27-US feet, EPSG 26791.

1-Modelspace set to MN-N. The survey has been scaled, rotated, made slightly transparent, then superimposed onto Bing imagery.1-Modelspace set to MN-N. The survey has been scaled, rotated, made slightly transparent, then superimposed onto Bing imagery.2-MAPCSASSIGN on commaand line. Search for MN-N. Select EPSG 26791.2-MAPCSASSIGN on commaand line. Search for MN-N. Select EPSG 26791.

 

The point you have highlighted with the red revision cloud is describing a point in PLSS, Public Land Survey System, an old, obsolete, drive you nuts, system used to divide and plat real estate. The system began in the 1700's prior to the invention of double AA batteries, Trimble handhelds and steel toe boots worn by field personnel who must comply with OHSA. Although absolutely archaic, it is still in service today (I wish the system would bye-bye, for good). It's immortality is phenomenal. It's probably because no matter what CS you use, it still holds sway.  

 

All you gotta do is scale the  your survey, perhaps rotate it a little too, then plop both the survey and the point in the rev cloud onto your x,y coordinates in modelspace. Then turn on Bing imagery. You should try, and use, different CS's that are applicable to your site, e.g. MN State Pln NAD 83, UTM83 zone 15, St Louis County system, MN-N NAD27. The last one worked (it's always the last one, I should've run through the list in reverse:). can also try different units, feet, meters, international feet, inches, etc. Since there are only a finite number of CS's, you are bound to 'hit it' especially when you use MAPCSASSIGN as opposed to establishing your CS from the  Civil Toolspace.

 

The key to this entire exercise is the first point from the opening post which is using St Louis County transverse Mercator 1996, it must be ignored. It has nothing to do with the price of tea in China nor this riddle. 

 

 

Chicagolooper

EESignature

Message 24 of 30

Oops! Sorry. Typo error.

The coordinates shown in magenta in the previous post were not correct. 

 

It should be like this.

 

Typo error, the x,y coordinates in magenta have been corrected.Typo error, the x,y coordinates in magenta have been corrected.

 

 

 

 

 

Chicagolooper

EESignature

Message 25 of 30
Anonymous
in reply to: ChicagoLooper

Ok, so I'm completely messed up...the two points that I said should match aren't even the same points (You were right since they obviously didn't match up upon converting)  SO, long story short, I have no points to compare... I do however still need the point converted that  is bubbled in red.   When I take that point and try and convert it to

NAD 27 Minnesota State Plane North Zone Coordinate System, the point comes in way off my map.    So NAD 27 Minnesota State Plane North Zone CS is not the correct CS.......  

 

Message 26 of 30
Anonymous
in reply to: ChicagoLooper

@ChicagoLooper   Because I'm sure I totally lost you by now.  I need x = 2058119.17 y = 355921.19 converted to US Survey Foot -  Saint Louis County Transverse Mercator 96.    I don't think the x, y was shot in

NAD 27 Minnesota State Plane North Zone Coordinate System.  So I don't know what CS it was shot in.....

 

 

Message 27 of 30
ChicagoLooper
in reply to: Anonymous

Haha, funny, but I am not lost. I'm still with you.

 

Image 1 shows coordinates in US-feet referenced to St Louis County Trans Merc 1996. Image 2 shows the same point described in image 1 against an aerial image using Global Mapper program..

 

(Just wondering, for the B&W survey you attached earlier with the red rev cloud, it was cropped. I dying to see the other survey notes on that page, footnotes and all. Is it possible to upload?)

 

1-Above are coordinates referenced to St Louis County Minnesota Trans Merc 1996, USft.1-Above are coordinates referenced to St Louis County Minnesota Trans Merc 1996, USft.2-This is same point described in image 1 with aerial image background in Global Mapper. The Coordinate sytem in St Louis County TM96, USft.2-This is same point described in image 1 with aerial image background in Global Mapper. The Coordinate sytem in St Louis County TM96, USft.

The geographic Lat/Long coordinates for the same point is 47.47551221, -92.86516291, degrees, LL84 (WGS84). I have also attached a kml file which you can open in Google Earth Pro (pls don;'t confuse this with Google Maps). While in Google Earth Pro, right click on the icon, then select 'Properties' to view the Lat/Long (Note: GE Pro allows you to input only 6 decimal places, if you input more, like I have, rounding will occur). 

 

 

Chicagolooper

EESignature

Message 28 of 30
Anonymous
in reply to: ChicagoLooper

@ChicagoLooper  I put in these points you just gave me and they seem to be correct!!!!! Easting: 4654532.01853501, Northing: 3594373.70787325

Message 29 of 30
Anonymous
in reply to: ChicagoLooper

@ChicagoLooper  The original B&W survey file is too big to attach 😞  But THANK YOU THANK YOU for helping me with this!!!

Message 30 of 30
Anonymous
in reply to: Anonymous

ขอบคุณนะคะKM

https://betufa.net/

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