The default adjustment in LGO will be holding the WGS 84 positions of the control points, i.e. Latitude, Longitude and Ellispsoid Height. Below we see the values provided by such an adjustment.

To compute orthometric heights (elevations), the geoid separation is simply added to the adjusted ellipsoid height in Tools | Compute Geoid Separations. This may or may not provide good elevations on your points, depending on the accuracy of the model.

If you wish to hold the orthometric heights, we need to do a local adjustment. In order to do a local adjustment, you need to have a coordinate system attached to the project. In our example we are using MI S (Michigan South NAD83).

The first thing we need to do is configure the adjustment for a local adjustment.

Right-click on a blank area of the adjustment page, and select Configuration | General Parameters...

Select the Coordinate System tab and choose Local Geodetic for the coordinate system.

Select the Height Mode as Orhtometric.

If you do not have sufficient control, you may need to disable the computation of the rotations and scale. To do so, right-click on the YES for the value(s) you don't want to compute and double-click on NO to disable it as seen in the following two images.

However, two horizontal and three vertical controls are sufficient to solve for all the values.

Click OK to save your configuration.

Now, we need to modify our control values and specify that we want to use the local position and its orthometric height and, if needed, we will also enter the correct orthometric height.

Right-click on a control point on the adjustment page and select properties. Make sure the Control class is selected.

Click the radio button in front of Local.

Click the radio button in front of Orthometric.

Enter in the correct elevation in the height field.

Note: If you want to hold the local grid coordinates (i.e.. the state plane coordinates) instead of the latitude and longitude, change the Coordinate Type to Grid instead of Geodetic and verify or enter the correct values.

Click OK to save the changes.

Repeat the editing for each of the control points.

Re-adjust the network.

Re-compute the geoid separations. (LGO does not do this automatically).

Our local values are seen below.

You will see that the orthometric heights have been adjusted to the orthometric heights of the control, and the ellipsoid heights have been re-computed by applying the geoid separations to the orthometric heights.

In this example I held 300.00 meters at 54102, 296.63 meters at BULLDOG, and 292.02 meters at NORM.

Your project is now adjusted to the local orthometric heights, and in the adjustment results output you will have a new section of additional parameters shown below.

Below we have two projects. The one on the right is the primary control survey from which we want to copy our control. The three points were surveyed in from HARN stations. In this case no adjustment was done. The three points were simply averaged using the measurements from the three HARN stations and we are going to use these averaged positions as control for our densification project. In this example station 54102 already has been fixed as control for a free adjustment and now we want to fix the other two stations for a constrained adjustment.

In the old project, right-click on the control station you want to copy to the new project and select Properties from the pop-up menu.

Select the Point Class you want to copy. In this case we've selected the Average point class of BULLDOG.

Click on the Copy Triplet button in the lower-left corner of the Point Properties dialog box as seen below:

Click the OK button to close the dialog box.

In the new project, right-click on the appropriate point (BULLDOG in this example) and select Properties from the pop-up menu.

Select the Control point class.

Click the Paste Triplet button in the bottom-left corner of the dialog box and you'll see the values change.

Click the Ok button to close the dialog box and your point will now have a control symbol shown in the View/Edit page.

Repeat the copy and paste for all the control points you need.