When I take off with my Phamton 4  and hover or fly about 6 - 8 feet off the ground the reading on my display says around 51 feet?  As I go higher it shows higher also. What should I be calibrating on the drone to correct this problem? I was under the impression that the height mesurement would be based on the distance from your take off point?

The height measurement is based on height above the launch point.
If the barometer is giving false altitude readings, you should recalibrate the IMU.
You can do that anywhere as long as it is in a perfectly level surface.

What is the VPS reading showing when the Altitude shows that high and you're much closer to the ground?  Just curious if the VPS cameras are also out of whack on your P4

Hi, I'm sorry to hear about the issue that you are experiencing. Please recalibrate the IMU and try it again, if still no good luck, please show us some photos of the problem, we'll look into it, thanks!

I had the experience of the drone displaying a higher than actual altitude.  I landed manually, shut down, restarted and it displayed correctly during subsequent flights.  Go figure.....