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Papa-Bear-NYC

Convert from "North American Datum" (around 1900?)

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I have a report of a survey done around 1915 which specifies the "North American Datum" as their control. It includes points in both Canada and the US (It's a boundary survey).

 

I'd like to convert some of the coordinates from the report to NAD83. Can someone tell me if conversion software is around for this datum? I could always assume it is close to NAD27 and convert from that but I'd rather do it right.

 

Thanks

Papa Bear

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I don't know of any software, and rather doubt that there is any, or any with a reliable degree of accuracy. The software that converts between NAD27 and NAD83 depends on large interpolation tables. I've never heard of any similar software or tables for earlier datums.

 

At best you might be able to find the old U.S. Standard/North American Datum coordinates of some nearby stations that also have modern coordinates, find a least squares transform, and then use that. Not something I would want to attempt, but it might the the best solution.

 

Otherwise, most GIS packages can take a map sheet image and georegister it to a current projection. If you have a map sheet from that period in the old North American Datum, that might be your best bet. Having said that, I have to warn you that the older maps are often not very accurate. I've done that kind of transform from some the the 1925 USGS quads to modern quads and orthophotgraphs, and there are often fairly large errors in some of the older maps.

 

If you are looking in the NYC area, take a look at the Maptech site to see if they have a pre-1930 quad for the region of interest. It should be in the old North American Datum, since the East Coast wasn't adjusted until the 1930's. You may be able to eyeball the location and find it on a current quad, and do a rough coordinate conversion that way.

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I don't know of any software, and rather doubt that there is any, or any with a reliable degree of accuracy. The software that converts between NAD27 and NAD83 depends on large interpolation tables. I've never heard of any similar software or tables for earlier datums.

 

At best you might be able to find the old U.S. Standard/North American Datum coordinates of some nearby stations that also have modern coordinates, find a least squares transform, and then use that. Not something I would want to attempt, but it might the the best solution.

 

Otherwise, most GIS packages can take a map sheet image and georegister it to a current projection. If you have a map sheet from that period in the old North American Datum, that might be your best bet. Having said that, I have to warn you that the older maps are often not very accurate. I've done that kind of transform from some the the 1925 USGS quads to modern quads and orthophotgraphs, and there are often fairly large errors in some of the older maps.

 

If you are looking in the NYC area, take a look at the Maptech site to see if they have a pre-1930 quad for the region of interest. It should be in the old North American Datum, since the East Coast wasn't adjusted until the 1930's. You may be able to eyeball the location and find it on a current quad, and do a rough coordinate conversion that way.

Thanks Holograph. This is the Canadian border in the northeast. There are old maps of the region online from the U of NH so that's a start. And furthermore I have the old and new coordinates of the major monuments on the border (the actual boundary monuments) so I can see the shift for those. Maybe for things within a few miles a straight linear shift may be sufficient for my needs. I just want to plot them on a map which has plenty of room for error anyway.

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I would echo some of the previous comments. The first thing I would try is to see if you can find any horizontal control stations in common between the old datum and NAD27 or NAD83. There are then programs that you can feed two sets of coordinates into and get an analysis and least squares coordinate transformation. Of course to do that would require listings of the old coordinates. It used to be such data was housed on sets of 5x7 cards. I would presume that NGS would still have that data somewhere, or you might find it in some local agency where some old surveyor likes to hang on to things like that.

 

Since you may not need a rigorous result, even one point would be a help and over a local area you could assign a simple shift. That could be done by finding even one point from your survey and putting a new coordinate on it with your GPS.

 

Some old C&GS publications may give some history of NAD27 and indicate regional shifts from the previous NAD.

 

-jlw

 

I have a report of a survey done around 1915 which specifies the "North American Datum" as their control. It includes points in both Canada and the US (It's a boundary survey).

 

I'd like to convert some of the coordinates from the report to NAD83. Can someone tell me if conversion software is around for this datum? I could always assume it is close to NAD27 and convert from that but I'd rather do it right.

 

Thanks

Papa Bear

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Have you tried downloading Corpscon, from the Army Corps of Engineers? It is good for converting between 1927 and 1983 datums. I'm not familiar with a North American Datum before 1927. Could the 1915 map have been revised at a later date to include the 1927 datum?

 

The website is http://crunch.tec.army.mil/software/corpscon/corpscon.html

 

I would recommend corpscon_base_conus.exe if you aren't interested in Alaska, Hawaii or vertical conversions.

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As a clarification, I have an old report that lists the Lat and Lng in the old datum. Some of the points are NGS stations for which I can look up the coordiantes in the current datum.

 

I guess the consensus is with that data, I can get a transformation of sorts for other points (for which I don't have mordern locations) near these particular points.

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Have you tried downloading Corpscon, from the Army Corps of Engineers? It is good for converting between 1927 and 1983 datums. I'm not familiar with a North American Datum before 1927. Could the 1915 map have been revised at a later date to include the 1927 datum?

 

The website is http://crunch.tec.army.mil/software/corpscon/corpscon.html

 

I would recommend corpscon_base_conus.exe if you aren't interested in Alaska, Hawaii or vertical conversions.

USACE's Corpscon (or NGS's NADCON) use the same interpolation tables that I mentioned. They can't do the first U.S. Standard / North American Datum (1913). For a brief history of the U.S. national datums, see this wiki page.

 

In the course of researching that page, I found that some of the old CGS annual reports contain published U.S. Standard / North American Datum (1913) coordinates for a limited set of locations. Usually the datums were realized by publishing books of coordinates as special CGS publications. Some of those publications are available online in Google books.

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Papa-Bear - There is no program that performs the transformation from NAD or the previous U.S. Standard Datum to either NAD 27 or NAD 83. Send me some detailed info about the area of your NAD survey and I will research the original control data that we maintain in the archives and I might be able to generate a local transformation.

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Papa-Bear - There is no program that performs the transformation from NAD or the previous U.S. Standard Datum to either NAD 27 or NAD 83. Send me some detailed info about the area of your NAD survey and I will research the original control data that we maintain in the archives and I might be able to generate a local transformation.

Thanks Dave. I'll email you the areas of interest.

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