![Earth Observatory SG on Twitter: "Apart from helping you find your way, #GPS is also used for measuring changes in land height, #sealevel & water vapour in the air! GPS is one Earth Observatory SG on Twitter: "Apart from helping you find your way, #GPS is also used for measuring changes in land height, #sealevel & water vapour in the air! GPS is one](https://pbs.twimg.com/ext_tw_video_thumb/1530036292691841024/pu/img/mdDLscshDP-NuDl-.jpg:large)
Earth Observatory SG on Twitter: "Apart from helping you find your way, #GPS is also used for measuring changes in land height, #sealevel & water vapour in the air! GPS is one
![The relationship of ellipsoid height (h), orthometric height (H), and... | Download Scientific Diagram The relationship of ellipsoid height (h), orthometric height (H), and... | Download Scientific Diagram](https://www.researchgate.net/publication/268516558/figure/fig3/AS:667665785966597@1536195336261/The-relationship-of-ellipsoid-height-h-orthometric-height-H-and-geoid-height-N-at.png)
The relationship of ellipsoid height (h), orthometric height (H), and... | Download Scientific Diagram
![Determination of Istanbul geoid using GNSS/levelling and valley cross levelling data - ScienceDirect Determination of Istanbul geoid using GNSS/levelling and valley cross levelling data - ScienceDirect](https://ars.els-cdn.com/content/image/1-s2.0-S1674984720300173-gr1.jpg)
Determination of Istanbul geoid using GNSS/levelling and valley cross levelling data - ScienceDirect
![How is a 0' sea level established for GPS measurements? My floating boat is currently reading 141' over sea level! : r/explainlikeimfive How is a 0' sea level established for GPS measurements? My floating boat is currently reading 141' over sea level! : r/explainlikeimfive](http://upload.wikimedia.org/wikipedia/commons/3/3b/Earth_Gravitational_Model_1996.png)
How is a 0' sea level established for GPS measurements? My floating boat is currently reading 141' over sea level! : r/explainlikeimfive
![Coordinates : A resource on positioning, navigation and beyond » Blog Archive » The Missing Observation: Orthometric Height Coordinates : A resource on positioning, navigation and beyond » Blog Archive » The Missing Observation: Orthometric Height](https://mycoordinates.org/wp-content/uploads/2012/04/eleiche2.jpg)
Coordinates : A resource on positioning, navigation and beyond » Blog Archive » The Missing Observation: Orthometric Height
![Modelling of Orthometric heights from Multi-Networks of GNSS / Precise Levelling in FCT , | Semantic Scholar Modelling of Orthometric heights from Multi-Networks of GNSS / Precise Levelling in FCT , | Semantic Scholar](https://d3i71xaburhd42.cloudfront.net/ef05375aab609e04a268d1162e1daad6c837f1c4/2-Figure1-1.png)