Elevation error

There are lots of reasons this could have occurred. I don't see any account for you in the system so please either share the link to the map, the name of the map, or your username so we can take a look. 

If you break your data collection up into 4 separate sections with 4 different takeoff locations you are going to have a hard time getting accurate elevation results. All efforts should be made to do all of your data collection with the same takeoff location. Otherwise it might be best not to upload any ground reference images at all and just let the system use the GPS derived numbers. 

This is in follow up to my previous post, above. (yes, different usernames, it's complicated!)

Over the past summer I have been flying a 2.5 by 3km block. due to other commitments, weather and other air traffic in the area my images were collected over a period of several months. Because of terrain potentially blocking the signal from the remote, and to minimize the distance flown to starting points I used several launch points for this project and had several ground images, at different elevations, different days, different barometric pressure...

I was not surprised when my DEM came out strange.

I ran the project again without the ground images, but the result was identical. I also had gaps in the image where I know I had images.

Any suggestions on how to resolve this this and get useful elevation data would be greatly appreciated.

The only real way to get good elevation results is to run the images from each takeoff separately. There is a reason we jump through all the hoops to correct for this using the ground reference images: the GPS altitude is totally unreliable. When you mix the unreliable numbers you get bad results. Once the error gets too high images get dropped.