---
title: "GPU Caustics"
canonical: "https://documentation.chaos.com/space/VMAX/113586778/GPU%20Caustics"
format: markdown
---
This page provides information on the Caustics  rollout under the V-Ray GPU Settings tab . Overview V-Ray supports the rendering of Caustics effects based on Photon mapping method. It is still a work in progress and has a few limitations(see below). The supported lights are V-Ray Plane/Disc lights, VRaySun and 3ds Max Direct and Spot lights. Known limitations: From file mode (saving and loading) is not supported. Textured lights are not supported. Motion-blurred lights are not supported. Projector maps for 3ds Max standard lights are not supported. Reflection glossiness and Refraction glossiness are not supported. Translucent materials - VRayAlsurfaceMtl, VRayFastSSS2 and VRayMtl with translucency set to SSS are not supported. IPR doesn’t update Caustics changes Parameters Caustics  – Turns rendering of caustics on and off. Search distance units  –  Specifies the caustics' photon lookup radius units between World (default) and Pixels. When V-Ray needs to render the caustics effect at a given surface point, it searches for a number of photons on that surface in the area surrounding the shaded point (search area). The search area is a circle. Its center is the original photon and its radius is equal to the Search distance value. Search dist  –  Specifies the photon lookup radius in pixels. Max photons  – Specifies the maximum number of photons that is considered when rendering the caustics effect on a surface. Smaller values cause fewer photons to be used, and the caustics are sharper but noisier. Larger values produce smoother but blurrier caustics.  Multiplier  - Controls the strength of the caustics. It is global and applies to all light sources that generate caustics.