Shapefiles projecting incorrectly with local coordinates and combination factor

545
9
06-16-2021 07:50 AM
Labels (1)
KaitlynAbrahamson
Occasional Contributor

I am trying to project several shapefiles created in CAD that show up too far north.  The projection in CAD is North Dakota North, International Foot with County Ground Coordinates. I have them projected in NAD 1983 StatePlane North Dakota N FIPS 3301 (Intl Feet) coordinate system right now and the projection is Lambert Conformal Conic.  I'm not sure why the map has that projection.  The CAD files also have a combination factor of 1.0001075116 and I'm not sure if that is why the shapefiles are not projecting in the correct location.  Does anyone have any suggestions to help me?

0 Kudos
9 Replies
DanPatterson
MVP Esteemed Contributor

is it a meters vs feet too far north, or a small amount that may be datum related?


... sort of retired...
0 Kudos
KaitlynAbrahamson
Occasional Contributor

It is only maybe 50 feet off.

0 Kudos
JayantaPoddar
MVP Esteemed Contributor

Keep a copy of your original data (one with North Dakota North, International Foot ) before moving forward.

Please check what happens if you use Define Projection (instead of Project tool) with NAD 1983 StatePlane North Dakota N FIPS 3301 (Intl Feet) [if the latitudinal extent of the data is between 47.15 to 49.01 DD].

 

Please check what happens if you use Define Projection (instead of Project tool) with NAD 1983 StatePlane North Dakota N FIPS 3302 (Intl Feet) [if the latitudinal extent of the data is between 45.93 to 47.83 DD]



Think Location
0 Kudos
KaitlynAbrahamson
Occasional Contributor

When I use Define Projection instead of Project, the files do not move with either tool.  I'm trying to establish a system to work through this each time it happens.  It happens fairly often when I get shapefiles with local coordinates and combination factors.

0 Kudos
DanPatterson
MVP Esteemed Contributor

50 feet is a datum issue.

To mitigate the apparent non-moving issue, you should add data to a map with no other data because the first layer that is added to a map sets its coordinate system.  Add other data after.

If your data doesn't have a defined coordinate system in the first place or one you are unsure of, then that is an important step.  Examine the coordinate system via its properties.  

Project should only be used once a shapefile has a defined coordinate system... a correct coordinate system, since defining something wrong will only make matters worse.

After using the Project tool, you can compare it to known/trusted data for placement... if it is off by 50 feet then it was defined wrong.


... sort of retired...
0 Kudos
KaitlynAbrahamson
Occasional Contributor

I tried what you described and added the shapefile to a new map.  It came in projected in the correct coordinate system, but the file is still over 50 ft off where it should be.  Is there something else I can do?  I don't want to have to move it manually.

0 Kudos
DanPatterson
MVP Esteemed Contributor

I would call Tech Support.  It still sounds like the file was defined incorrectly in the first place (incorrect datum? ) or an appropriate datum shift wasn't applied during the Project operation.


... sort of retired...
0 Kudos
KaitlynAbrahamson
Occasional Contributor

Do you think the CAD files are off?  This happens quite frequently because the files I'm working with are made with local coordinates that rarely project correctly.  Unfortunately, this happens a lot and I'm forced to move them manually when I can.

0 Kudos
DanPatterson
MVP Esteemed Contributor

If you are doubting the cad files, I would start there.  Nothing is going to go well if you have suspect data going in


... sort of retired...
0 Kudos