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title: "VRayMtl Refraction"
canonical: "https://documentation.chaos.com/space/VMAYA/111738896/VRayMtl%20Refraction"
format: markdown
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> Macro (anchor)



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### **Example: Refraction IOR**


This example demonstrates the effect of the Refraction **IOR **parameter. Note how light bends more as the IOR deviates from 1.0. When the index of refraction (IOR) is 1.0, the render produces a transparent object. Note, however, that in the case of transparent objects, it might be better to assign an opacity map to the material rather than use refraction.



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> ⚠️ V-Ray provides several other ways to achieve sub-surface scattering, for example the **VRayFastSSS2** and **VRayALSurfaceMtl** materials. These materials use various approximations for the sub-surface scattering effect in order to speed up the calculations. In many cases they produce a decent result. However in more complicated scenarios, the approximations may be inaccurate.
> ⚠️ 
> ⚠️ ![alSurface_example_Fog.png](media://a6897531-1fb7-49b5-a053-957203dae48e)
> ⚠️ 
> ⚠️ ![alSurface_example_Fog2.png](media://bad7bf07-72b0-4d8b-a2e2-b4fa8403697e)
> ⚠️ 
> ⚠️ The approximation used in the VRayAlSurfaceMtl assumes a mostly flat surface, therefore in areas of high geometric detail and relatively large scattering radius it tends to produce inaccurate results that don't capture the details very well. In addition, the Directional mode of the VRayAlSurfaceMtl material may introduce unwanted color shifts.


> Macro (anchor)



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### **Example: Fog Color**


This example demonstrates the effect of the **Fog color** parameter. Notice that we are changing  
the hue value of the Fog color. Translucency is set to **None**.



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### **Example: Scale (cm)**


This example demonstrates the effect of the **Scale (cm)** parameter. Translucency is set to **SSS**.



> Macro (anchor)



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### **Example: Refraction Depth**


This example demonstrates the effect of the refraction **Max depth** parameter. Note how too low of a refraction depth produces incorrect results. Also, in the last two examples, note how areas with total internal reflection are also affected by the Reflection **Max depth**.