# Cesion Ion does not generate watermask for my uploaded DEM in GeoTIFF format

**URL:** <https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069>\
**Category:** Cesium ion\
**Created:** [August 22, 2022, 9:09pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069 "2022-08-22T21:09:22Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![0x974](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/0x974/32/3476_2.png) [@0x974](https://community.cesium.com/u/0x974)\
**Post date:** [August 22, 2022, 9:09pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/1 "2022-08-22T21:09:22Z")

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Hello,

Cesion Ion does not generate watermask (nor bvh) for my uploaded DEM in GeoTIFF format.

Is it an expected behavior?

Thanks.

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**Author:** ![Shehzan\_Mohammed](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/shehzan_mohammed/32/2002_2.png) [@Shehzan\_Mohammed](https://community.cesium.com/u/Shehzan_Mohammed)\
**Post date:** [August 23, 2022, 1:57pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/2 "2022-08-23T13:57:02Z")

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Can you elaborate on your issue? All assets uploaded as terrain always have watermask generated if the source indicates no-data over a water body. Have you turned on the watermark in CesiumJS to be sure? See [Cesium Sandcastle](https://sandcastle.cesium.com/index.html?src=Lighting.html).

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**Author:** ![0x974](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/0x974/32/3476_2.png) [@0x974](https://community.cesium.com/u/0x974)\
**Post date:** [August 23, 2022, 7:24pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/3 "2022-08-23T19:24:06Z")

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Sure, I can elaborate:

The source is a custom source (GeoTIF) I uploaded via Cesium Ion.  
I tried of course to enable the watermark option in Cesium for Unreal, in vain. Maybe I did it the wrong way.  
Then I looked at the `layer.json` of my data source, which does not contain `watermark` in `extensions`.

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<div class="post-metadata">

**Author:** ![Shehzan\_Mohammed](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/shehzan_mohammed/32/2002_2.png) [@Shehzan\_Mohammed](https://community.cesium.com/u/Shehzan_Mohammed)\
**Post date:** [August 24, 2022, 4:27pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/4 "2022-08-24T16:27:58Z")

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Hi

Are you able to share the link from the “Open complete code example” from the Cesium ion Asset?

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<div class="post-metadata">

**Author:** ![0x974](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/0x974/32/3476_2.png) [@0x974](https://community.cesium.com/u/0x974)\
**Post date:** [August 25, 2022, 10:33am UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/5 "2022-08-25T10:33:54Z")

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Sure I do (in DM because of access token)!

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<div class="post-metadata">

**Author:** ![Shehzan\_Mohammed](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/shehzan_mohammed/32/2002_2.png) [@Shehzan\_Mohammed](https://community.cesium.com/u/Shehzan_Mohammed)\
**Post date:** [August 25, 2022, 2:21pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/6 "2022-08-25T14:21:46Z")

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Thanks for sharing that.

The reason there is no watermask is because you did not select a base terrain (like Cesium World Terrain). When you upload a “regional” terrain raster and want the watermask to be turned on, anything that isn’t part of the terrain will also be considered water, and hence not the desired effect. Watermask is set based on the “no-data” or negative height values, and anything beyond the terrain you have uploaded will be considered as nodata automatically.

The way to solve this would be to upload the terrain and select CWT or other base terrain that has a water mask.

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<div class="post-metadata">

**Author:** ![0x974](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/0x974/32/3476_2.png) [@0x974](https://community.cesium.com/u/0x974)\
**Post date:** [August 25, 2022, 8:51pm UTC](https://community.cesium.com/t/cesion-ion-does-not-generate-watermask-for-my-uploaded-dem-in-geotiff-format/20069/7 "2022-08-25T20:51:32Z")

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Thank you very much for that explanation!