Mix of Coordinate System datums

[Mark Wheeler]

We are working on an old army base. The site coordinate system is NAD83/NGVD29. What Geoid should I use for NGVD29?

Mark

 

[Matthew D. Sibole]

NGVD29 does not have a Geoid associated with it. However, I would use Geoid18 and adjust elevations to a known benchmark.

 

[Mark Wheeler]

Matt,
1. In the coordinate system set up, if I selected NGVD29 with no Geoid, would the elevations come in as NGVD29?
2. If Geoid 18 is selected, where do you input the vertical shift between 88 and 29 for that local? Or do you have to localize?

 

[Matthew D. Sibole]

You would have to do a one point localization.

 

[Shawn Billings]

Matt is exactly correct.

 

[Mark Wheeler]

sounds good