CAD to feature class produces identical feature class when using NAD27 and NAD83 State Plane Coordinate Systems

Question

I have a georeferenced CAD file that I imported into ArcGIS Pro v2.4. I had initially imported the CAD file into a map with coordinate system NAD 1983 StatePlane New Mexico West FIPS 3003 Feet.  I later learned the coordinate system the CAD file should actually be in was NAD 1927 StatePlane New Mexico West FIPS 3003.  In both cases, I converted the CAD file using the Feature Class to Feature Class tool, selecting the appropriate coordinate system. The result was two feature classes that were exactly on top of each other. I expected to have the feature classes be slightly different from one another.

Can someone explain what is going on here? I've attached a portion of the CAD file and the feature classes.

CAD_file.zip

SHPs.zip

DA28D13A-2F4C-4324-9378-5CCFCC8814CC.jpeg

ShengdiZhang_0-1720510595305.png

DanPatterson · Answer

No clue at this point, ... unless it was wrongly correctly defined 😉

MeganKrajewski · Answer

Thanks Dan. So that's not quite the issue because one of the CAD files was incorrectly defined in the first place (the 1983 version was incorrect).  I expected defining the CAD file with the correct 1927 version would shift the CAD file slightly, but it didn't.

The problem is that when I bring the CAD file into two different maps with different coordinate systems and define the coordinate system for the CAD file in those maps, I get the CAD file to land in the same location. So it's not really an issue with on the fly projections, but rather defining a CAD file with two different projections and getting the CAD file in the same location.

Hopefully that better explains the issue I'm having and you or someone else can help me understand. Thanks!

DanPatterson · Answer

Properly defined coordinate systems will project-on-the-fly to match the coordinate system of the map.  Nothing is wrong.  Featureclasses with different datums and coordinate systems can be mixed in one map... that is the purpose of the on-the-fly projection.  It provides a mechanism for people to view data without having to project to a common coordinate system first.