# ThinInstances Render different Visually than Instances? **URL:** \ **Category:** Questions\ **Created:** [September 18, 2023, 12:06am UTC](https://forum.babylonjs.com/t/thininstances-render-different-visually-than-instances/44213 "2023-09-18T00:06:52Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Pryme8](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/pryme8/32/7212_2.png) [@Pryme8](https://forum.babylonjs.com/u/Pryme8)\ **Post date:** [September 18, 2023, 12:06am UTC](https://forum.babylonjs.com/t/thininstances-render-different-visually-than-instances/44213/1 "2023-09-18T00:06:52Z")
> **[Babylon.js Playground](https://playground.babylonjs.com/#FIXETD%232)** > > Babylon.js playground is a live editor for Babylon.js WebGL 3D scenes If you comment out line 65 you will see what I mean. Thin Instances: ![image](https://us1.discourse-cdn.com/flex024/uploads/babylonjs/original/3X/5/6/5632a68dab4f9ec314e79edec9f7b9beb562a6a5.png) Instances: ![image](https://us1.discourse-cdn.com/flex024/uploads/babylonjs/original/3X/c/9/c94339800201e718501e72265eb10cab01258089.png) Its like the specular is borked? ---
**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\ **Post date:** [September 18, 2023, 8:23am UTC](https://forum.babylonjs.com/t/thininstances-render-different-visually-than-instances/44213/2 "2023-09-18T08:23:48Z")
For performance reasons (to avoid calculating the inverse of a matrix per thin instance), we use a simplified normal calculation in the case of thin instances that does not support non-uniform scaling, only uniform scaling. We could add a flag to switch to the exact calculation, if you need it (the best solution would be to avoid non-uniform scaling altogether, though 🙂)?