# Correct elevation above sea level

**URL:** <https://community.cesium.com/t/correct-elevation-above-sea-level/15880>\
**Category:** CesiumJS\
**Created:** [October 27, 2021, 10:37am UTC](https://community.cesium.com/t/correct-elevation-above-sea-level/15880 "2021-10-27T10:37:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![QuartzReservoir](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/quartzreservoir/32/4081_2.png) [@QuartzReservoir](https://community.cesium.com/u/QuartzReservoir)\
**Post date:** [October 27, 2021, 10:37am UTC](https://community.cesium.com/t/correct-elevation-above-sea-level/15880/1 "2021-10-27T10:37:54Z")

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I know this has been discussed before, but is there any further information about how to obtain the correct elevation (height) above sea level?  
For example when digitising points on the terrain or ensuring sea level is zero?  
I have used the example “Drawing on Terrain.html” that was posted on Github, using Cesium terrain.  
var earthPosition = viewer.scene.pickPosition(event.position);  
Cesium.HeightReference.CLAMP\_TO\_GROUND.

Anything built-in or are there any approximations that can be used?

Any help appreciated.

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**Author:** ![sam.rothstein](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/sam.rothstein/32/6584_2.png) [@sam.rothstein](https://community.cesium.com/u/sam.rothstein)\
**Post date:** [November 1, 2021, 12:24am UTC](https://community.cesium.com/t/correct-elevation-above-sea-level/15880/2 "2021-11-01T00:24:30Z")

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@QuartzReservoir

Thank you for your question! I recommend checking out the following two community forum threads for more information and context about how CesiumJS handles elevation.

- [Elevation off by 30m?](https://community.cesium.com/t/elevation-off-by-30m/14130)
- [Elevation data from Cesium Terrain Providers is wrong?](https://community.cesium.com/t/elevation-data-from-cesium-terrain-providers-is-wrong/1654)

As always, let me know if you have any other questions or concerns!

-Sam