# A problem about flat model

**URL:** https://community.cesium.com/t/a-problem-about-flat-model/21818
**Category:** Cesium for Unreal
**Created:** [January 5, 2023, 12:57am UTC](https://community.cesium.com/t/a-problem-about-flat-model/21818 "2023-01-05T00:57:37Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![hio\_wang](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/hio_wang/32/12983_2.png) [@hio\_wang](https://community.cesium.com/u/hio_wang)
#### Post date: [January 5, 2023, 12:57am UTC](https://community.cesium.com/t/a-problem-about-flat-model/21818/1 "2023-01-05T00:57:37Z")

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I tried to unfold the global earth into a flat model by used the GeographicProjection file,just like this.

 ![img1](https://global.discourse-cdn.com/cesium/original/3X/d/4/d42f5e87df12435ebb68c1df7d3005eee1175a37.png)  
But unfortunately, When I try to align the coordinate system with UE’s coordinate system ( by change this function:UCesium3DTilesetRoot::\_updateTilesetToUnrealRelativeWorldTransform) , Terrain tiles flicker very badly and as soon as we select the “World terrain” in editor, flickering stops. (just like two pictures at the end,Reciprocating refresh).  
By the way, If I don’t make changes, it won’t happen.How can I solve this problem? Thanks in advance.  
 ![0F69DF1B-6CAD-4dde-83C2-98D641FD20AA](https://global.discourse-cdn.com/cesium/original/3X/3/7/37b162a2ddb3fb6e5a40fa74e32fdba56bb26e76.png)  
 ![5AAB20A3-0D58-4bcd-968E-FCACECC1D77F](https://global.discourse-cdn.com/cesium/original/3X/d/e/de68c49f0cdfcdee53e2b4b0e1a9efab2fa46d45.png)