# Detect Terrain and Line intersection point

**URL:** <https://community.cesium.com/t/detect-terrain-and-line-intersection-point/15751>\
**Category:** CesiumJS\
**Created:** [October 18, 2021, 1:21pm UTC](https://community.cesium.com/t/detect-terrain-and-line-intersection-point/15751 "2021-10-18T13:21:41Z")\
**Posts on this page:** 1\
**Showing post:** 2

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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:** [October 18, 2021, 7:19pm UTC](https://community.cesium.com/t/detect-terrain-and-line-intersection-point/15751/2 "2021-10-18T19:19:07Z")

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@Hazel-Leylak

Thank you for bringing this question to the community! Intersection detection is a very common CesiumJS question. What kind of objects are you looking to detect the intersection of? In the meantime, I recommend checking out these community forum threads. I believe that they address similar questions.

> [@I want to find the intersection points where a polygon intersects a terrain](https://community.cesium.com/t/i-want-to-find-the-intersection-points-where-a-polygon-intersects-a-terrain/8046):
>
> Hi there, Is there any way to find the intersection points where a polygon(having height) intersecting terrain. The Cesium version you're using, your operating system and browser. Cesium 1.52, Win 10, Chrome

> [@How to get intersection of a ray from the camera and 3d terrain?](https://community.cesium.com/t/how-to-get-intersection-of-a-ray-from-the-camera-and-3d-terrain/8646):
>
> 1. A concise explanation of the problem you’re experiencing. I need to get the intersection point of a ray from the camera to 3d terrain. Cesium.IntersectionTest() seem to use only the ellipsoid, 2. A minimal code example. If you’ve found a bug, this helps us reproduce and repair it. var intersectionPoint = function(){ var ellipsoid = viewer.scene.mapProjection.ellipsoid; var windowCoordinates = new Cesium.Cartesian2(elmnt.offsetHeight / 2, elmnt.offsetWidth / 2); var ray = viewer.camera.…

Please let me know if you have any other questions or concerns. I am looking forward to learning more!

-Sam

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