I have heretofore been using Ashtech Solutions but have been toying around with GNSS Solutions with some old files and see one obvious difference in respect to heights.

In AS you could specify orthometric heights on your control points. In GNSS, it appears the software is automatically assigning that when you specify a preset coordinate system, in my case Illinois West. When you use the define control points from the pull down menu, it asks for an ellipsoid height but I'm pretty sure it's really asking for an orthometric height because when the control tab is clicked after entering it, it shows orthometric and ellipsoid heights as the same.

If I accept that the control point elevations are indeed really orthometic heights and not ellipsoid heights it processes elevations nearly the same as the receiver files did in AS.

There is however, a check box for changing the vertical offset under the coordinates pull down, which implies that you could do that, but I am having trouble doing that however because it sets up a new system and won't let you delete the old one.

I need some verification that when you use the preset coordinate system wizard that it assigns the elevations as orthometric heights if you choose a state plane coordinate system – even though in the define control points interface it's asking for ellipsoid heights.

Leaves me a little bit confused.

Thanks.

Way back when I set it up, I added SPC Ellipsoid and SPC Ortho to my systems list. It is inconvenient to add new systems and I generally have to resort to the manual.

I would never rely on any automatic setup wizard.

Calculating with ortho elevations will throw a lot of poo in your results. Ortho elevations are often based on leveling. Please stick with the ellipsoid then convert to ortho elevations.

There is an application note named

GNSS Solutions - customizing the coordinate list

you can find it on the ftp server at

ftp://ftp.magellangps.com

It will help you figure this out.

Worked like a charm.

I like how you can setup different coordinate systems and save them for future use.

Nice feature...