Just found this and started using it to help myself to be able to eyeball the height of different objects. Not something to rely on for setting RTH or waypoint heights, more to help train the brain to recognize different heights. I use it even when not flying and just around town.
EasyMeasure - Measure with your Camera! on the App Store
You do have to pay for the ability to measure heights, the usual $.99.
EasyMeasure - Measure with your Camera! on the App Store
You do have to pay for the ability to measure heights, the usual $.99.