What coordinate system is this in my .dwg file?

[AwesomeEvan]

I'm working in Orangeville, Ontario, Canada.

We are in NAD 83 UTM Zone 17N, which has coordinates in the center of town at about (572267 E, 4863235 N)

I have CAD drawings where at the same location, coordinates are about 1969257, 4483224, with no coordinate system identified in the .dwg file.

I'm trying to get the line work into arcmap.

Could this be a different coordinate system or perhaps it's completely incorrectly positioned?

Any suggestions of how I can get the line work properly aligned into arcmap would be greatly appreciated.

Cheers.

[ChrisDonohue__GISP]

There are several possibilities:

• Given that the file is AutoCAD and most people in the AutoCAD world don't deal with projected data, it is entirely possible it is a "Local" projection - i.e. the CAD operator set the Southwest-most portion of the site to 0,0 and then worked from there.
• It may be in a commonly-used coordinate system for the Ontario area.  Though the coordinates you posted don't adhere to the best-practice used with established coordinate systems of having the Northings and Eastings values one order of magnitude different so as to allow users to quickly establish which is which from just the numbers should the data header information get lost.  However, just to muddy things up, this best practice is not used by all coordinate systems.

I'd look into the available coordinate systems for your province.

How To: Identify the spatial reference, projection, or coordinate system of data

Also, let me add someone who may know it off the top of his head:

Dan Patterson

Chris Donohue, GISP

[DanPatterson_Retired]

not utm, not mtm

FAQ: What are some common projections and geographic coordinate systems for Canada? is for canada, BUT

being ontario, check for MNR projections.  The east west extent suggests a lambert conformal conic which is used in the place of albers in Canada.  That would be my guess.

If you ever get data, especially old cad data from the ont gov, that seems to be south of georgia, it is UTM with 4,000,000 subtracted from the northing (not a budget cut issue, but an old-day data storage issue).

So  check where you got the data from, if it is in anyway tied to the provincial gov't look on their gis site.  For the feds, likewise... and lest we not forget, esri canada, TO office is closer to you.

[AwesomeEvan]

Thanks, I tried several 'common projections' out with no success . . . I think with the data at hand I'm opting to recreate it manually. It's not the most cumbersome task in this case, and i can create it from parcels... however it just feels wrong 

thanks for the help

[DavidRenaud]

It might be easier to work in Autocad: create a new Acad dwg in the correct system, bring in the old data and move/rotate it (ALIGN) using common points to get it coordinately correct. pretty simple operation to do all the objects at once, but it depends on having good quality common points. also, watch/check the Z values.