# Issue processing OBJ in Cesium ION when filenames .obj and .mtl filenames are not aligned

**URL:** <https://community.cesium.com/t/issue-processing-obj-in-cesium-ion-when-filenames-obj-and-mtl-filenames-are-not-aligned/44949>\
**Category:** Cesium ion\
**Created:** [January 23, 2026, 3:43pm UTC](https://community.cesium.com/t/issue-processing-obj-in-cesium-ion-when-filenames-obj-and-mtl-filenames-are-not-aligned/44949 "2026-01-23T15:43:03Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![DigitalFBX](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/digitalfbx/32/32828_2.png) [@DigitalFBX](https://community.cesium.com/u/DigitalFBX)\
**Post date:** [January 23, 2026, 3:43pm UTC](https://community.cesium.com/t/issue-processing-obj-in-cesium-ion-when-filenames-obj-and-mtl-filenames-are-not-aligned/44949/1 "2026-01-23T15:43:03Z")

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Dear community,

Uploading OBJ data, when the main .obj filename is not aligned with the .mtl material filename, CESIUM.ION is not able to process the 3D Tiles and fails.

This comes as a surprise, as the **material filename is usually included inside the .obj** as below.

 ![image](https://global.discourse-cdn.com/cesium/original/3X/f/8/f8f449afa5eda69978a406b24fcbc4cb21ac0649.png)

Using the same data but renaming the main .obj file, one succeeded and the other failed.

 ![image](https://global.discourse-cdn.com/cesium/original/3X/8/5/85a19fe4f4b7ca9a3709e9449c6402dfb1bce1a4.png)

If any restrictions applies regarding naming conventions, please let us know.  
Thanks for your amazing work!