# Is there any way to modify the default transformation “TEME \<-\> ECF” of the Cesium

**URL:** <https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390>\
**Category:** CesiumJS\
**Created:** [April 30, 2022, 7:02am UTC](https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390 "2022-04-30T07:02:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Lemonsky](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/lemonsky/32/9119_2.png) [@Lemonsky](https://community.cesium.com/u/Lemonsky)\
**Post date:** [April 30, 2022, 7:02am UTC](https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390/1 "2022-04-30T07:02:01Z")

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Hello，  
Is there any way to modify “TEME \<-\> ECF” transformation to “J2000 \<-\>ECF” transformation ? I’m not familiar with this transformation. But I need “J2000 \<-\> ECF” transformation .

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**Author:** ![Kevin\_Ring](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/kevin_ring/32/2003_2.png) [@Kevin\_Ring](https://community.cesium.com/u/Kevin_Ring)\
**Post date:** [May 2, 2022, 9:01am UTC](https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390/2 "2022-05-02T09:01:02Z")

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Hi @Lemonsky,

I’d suggest taking a look at the ICRF methods. At the risk of oversimplifying, ICRF is like J2000 except more accurate.

For the most accurate transformation, you must supply Earth Orientation Parameters (EOP) by setting `Transforms.earthOrientationParameters`. The documentation for Cesium’s `EarthOrientationParameters` class has an example of the format that is required:  
[https://cesium.com/downloads/cesiumjs/releases/b29/Documentation/EarthOrientationParameters.html](https://cesium.com/downloads/cesiumjs/releases/b29/Documentation/EarthOrientationParameters.html)

You can get updated EOP data from Celestrak:  
[https://celestrak.com/SpaceData/](https://celestrak.com/SpaceData/)

Depending on your application, it may not be worth the trouble as the visualization difference won’t be very noticeable, but I can’t say for sure.

Kevin

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<div class="post-metadata">

**Author:** ![Lemonsky](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/lemonsky/32/9119_2.png) [@Lemonsky](https://community.cesium.com/u/Lemonsky)\
**Post date:** [May 11, 2022, 2:38pm UTC](https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390/3 "2022-05-11T14:38:35Z")

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@Kevin_Ring Thanks，I will do some try.

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**Author:** ![Scott\_Hunter](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/scott_hunter/32/2006_2.png) [@Scott\_Hunter](https://community.cesium.com/u/Scott_Hunter)\
**Post date:** [May 11, 2022, 5:51pm UTC](https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390/4 "2022-05-11T17:51:47Z")

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For future reference, we generate EOP.json data on a daily basis which is available from:

[https://ftp.agi.com/pub/DynamicEarthData/](https://ftp.agi.com/pub/DynamicEarthData/)

specifically [EOP.json](https://ftp.agi.com/pub/DynamicEarthData/EOP.json) and [EOP-All.json](https://ftp.agi.com/pub/DynamicEarthData/EOP-All.json)

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<div class="post-metadata">

**Author:** ![Kevin\_Ring](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/kevin_ring/32/2003_2.png) [@Kevin\_Ring](https://community.cesium.com/u/Kevin_Ring)\
**Post date:** [May 11, 2022, 11:34pm UTC](https://community.cesium.com/t/is-there-any-way-to-modify-the-default-transformation-teme-ecf-of-the-cesium/18390/5 "2022-05-11T23:34:14Z")

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Thanks @Scott_Hunter, that’s good to know!

I just realized I linked to a really old version of the CesiumJS reference docs, but in the latest versions of CesiumJS the EarthOrientationParameters class is marked private. I wonder if we should make it public and also document that the data is available from AGI. Assuming AGI doesn’t mind providing that as a service to the community at large.

Kevin