Any Surveyors Here. ?

[bluff]

Hi all. Frequent lurker new poster.

I have a survey map and I am having trouble figureing out the map datum. I did a search and didn't see the info I'm looking for.

There are several points on the map that look like this:

 

N892920.67928

E2298666.44300

 

How do I convert this to something I'm familiar with?

There is nothing on the map to indicate format or datum except the letters DGN.

Any help is appreciated.

 

Bluff

[+geckoee]

Since 2002... Welcome to the realms of the posting side of the forums. Hopefully this will be a pleasant experience

 

Looks like UTM to me. aka Universal Trans Mercator. They are distances measured north and east of a center. There should be a zone on there some where, like 19T or 11S. The united states covers about 18 grids, so it should be pretty easy to figure out what center you are in even if it's not on the map.

 

DGN is a rectangular grid file format used by mapping software. Maybe this is the source of the map data?

 

Unfortunately this tells you nothing of your datum, just your grid system.

Edited March 17, 2004 by geckoee

[Curious George]

Yup looks like UTM to me as well - you can get some good information about UTM on this site. Also check your GPS manual, you can swith the co-ordinate system to UTM and enter the numbers, then change back to the familiar lat/long and your GPS will do the conversion for you. But you do need to know what UTM zone you are in.

[+Waterboy]

Without more information I would guess this is in State Planar Coordinates. Most likely the numbers are in feet, since there are seven digits easting coordinate.

 

There are over 120 different state planar coordinate systems used in the USA. Each state has at least one system, with larger states have more. I just checked your home state of Illinois, it uses two systems. Now the problem is to figure which of these coordinate systems it is. Please tell us where you think the map is located.

[+Renegade Knight]

I'll second Waterboy if you know where the maps is at you can determine which State Plane Coordinates to use. It's the best guess you can have. A good map would provide the information needed to nail down what coordnates are used so another surveyor can come up with the same map if needed.

[+geckoee]

....Most likely the numbers are in feet, since there are seven digits easting coordinate.

On a second look: If those were meters, it would put you 3 zones away from the grid center! If the East coordinate is in feet, that's about 435 miles from the grid center. That's pretty big even for Texas. Although most large states have several zones. Maybe it's a more national grid, or some other country?

 

what about the precision of the numbers? 5 digits for meters would be 1/10ths of millimeters. For feet it would be smaller! Is that something you see on survey grade benchmarks?

Edited March 17, 2004 by geckoee

[bluff]

Thank you for the welcome. Although I have been a member since 2002 I'm still relatively new to this sport ( basic cache stuff) and I knew I could come here for good information. I was not disappointed.

Geckoee it is in feet to 1/100 of a foot.

Waterboy and Renegade my general location is: (no cruise missiles please )

 

39.1029N

90.4977W

Again thanks. Anymore info is greatly appreciated. I'm going to walk the property of interest this coming weekend if possible.

 

Bluff

Edited March 17, 2004 by bluff

[Kerry.]

Without a Datum then one is a little lost. I do find it strange that a survey map has coordinates to 5 decimal places, that's a bit over the top really.

 

"DGN" is a Intergraph/Bentley (mapping) file format but has no bearing on the particular units used in the file, and what they mean on this particular map, not sure.

 

Cheers, Kerry.

[+Waterboy]

This appears to be using the Illinois West State Planar coordinate system NAD83. Still the figures are off. The coordinates:

N892920.67928

E2298666.44300

 

And the coordinates

39.1029N

90.4977W

 

The first set (State Planar) when converted to NAD83 is equal N 39º07’07.9” W090º09’33.6” or N 39º07.130’ W090º09.559’ or N 39.11883º W 90.15932º. This is a distance of about 18 miles from the second set of coordinates. Bluff, is this 18 mile distance reasonable?

 

I considered the possibility of these State Planar coordinates being in NAD27 datum. The result was a longitude of W083º, clearly out of western Illinois.

 

The conversion from State Planar coordinates was done using a free download program made available by the Army Corps of Engineers named

Corpscon.

 

Note on five decimal places – Although the least significant figures are meaningless, they will occur on survey maps. Sometimes it is a reference telling you that it was converted from another system/datum. Sometimes it is for legal reasons.

[+wolf452]

Bluff, since you are in West Illinois, I converted these from West Zone State Plane to Nad 27 and located on a Quad sheet. They appear to be on the north end of a pond in Section 24, T8N, R10W of the 3rd PM, in Jersey County, IL. Correct?

As a Surveyor we report numbers like these on DOT drawing mostly.

[Kerry.]

As a Surveyor we report numbers like these on DOT drawing mostly.

What! too five (5) decimal places

 

Cheers, Kerry.

[+Cache Viking]

Without a Datum then one is a little lost. I do find it strange that a survey map has coordinates to 5 decimal places, that's a bit over the top really.

 

"DGN" is a Intergraph/Bentley (mapping) file format but has no bearing on the particular units used in the file, and what they mean on this particular map, not sure.

 

Cheers, Kerry.

I seem to recall with the first release of Intergraphs MGE product it defaulted to UTM Grids and was dificult to use with secondary units such as our State Plane Coordinates.

 

I agree 5 places is a strange number to stop at. We generally never wrote down more than 2 and left the rest to reside on the computer for future calculations.

 

Are there any other marks on the map to show if it is filed with a government agency that may be able to say what they used?

[bluff]

Well it appears you guys are really close. I have not been to this property yet.

I found a survey document from a place I know, that is around 10 mi. S. and around the same E. of this property that has info I think would help.

 

State Plane Coordinate Position - NAD 27

Illinois Coordinate System Zone: West

X: 463,327.9 Y: 830,049.0

Coordinates derived by adjusted traverse from COE

hoizontal control station K210.9L, 1983

edit: Sec 24 T6N R11W of 3rd PM. Jersey Co. Il.

 

Here is a GPS coordinate from this area. N38.94254 W90.29059

I have a yellow Etrex. My main question would be. Can I set my GPS up and plug in some numbers and convert?

 

 

thanks

Edited March 19, 2004 by bluff

[bluff]

Thanks for your help guys. I'm going to walk this property in the morning.

With the info and links provided I think I can muster my way through it. I definately need to learn how to decipher a survey map and learn UTM.

 

Bluff

[bluff]

Walked the property, found the survey marks, created my own waypoints and made a map.

[+Waterboy]

Thanks for your help guys. I'm going to walk this property in the morning.

With the info and  links provided I think I can muster my way through it. I definately need to learn how to decipher a survey map and learn UTM. 

 

Bluff

The first thing to learn about UTM is that you are not using them in your example, you are using a completely different system called “State Planar Coordinates”.

 

State Planar, UTM, and Lat/Long are three different systems. All are currently used and have advantages and disadvantages. Some states require that surveys be performed using the applicable State Planar Coordinates. I do not know if Illinois requires its use.

[bluff]

I'm learning.