Step 9: Setting up Caustics in mental ray
- Return to the top viewport and make sure you have a good view of all of your spherical objects and light. First, we're going to tell mental ray which of our objects will be producing caustics. Using your Select Tool, select mr Area Spot01, right click on it to call up the Quad Menu, scroll down the lower right Transform panel to Properties and click. This will call up the Object Properties panel. Click the mental ray tab, and in the mental ray Rendering Control area enable the Generate Caustics checkbox, see images below:
Now, repeat this step with the four remaining objects, Sphere01, Sphere02, Sphere03 and GeoSphere01 (Plane01 and the camera are not a part of the caustics setup, so ignore these objects). You can also do this in a group by hitting H and selecting these objects all together, then right clicking anyone of them in the top view to set them to generate caustics as outlined above. The last part of setting up mental ray for our project is to instruct mental ray to render caustics. Hit C to return to your camera view. Hit F10 to call up Render Scene: mental ray Renderer dialogue. Open the Indirect Illumination tab, and in the Caustics area of the Indirect Illumination rollout, click the checkbox to Enable caustics. Leave all other settings to their defaults for now. Click the Render button. If followed carefully, your scene should look like the image below:
Save your file.
Step 10: Realism in Caustics
- Before getting into this step, it's important to know what caustics truly are. Caustics is what happens to light/photons after being subjected to either refraction through an object or reflection off of an object. Case in point, note the refraction AND reflection of light of and through GeoSphere01. Shouldn't this object also be reflecting tiny shards of light onto the plane surface? And what about the refraction of light through it? Shouldn't tendrils of light be in the shadow field? Actually, it IS there, but with our default settings these are not going to be so readily visible. Let's correct that now. Our default settings are good enough to give us a fairly good render without having to wait an unusual length of time for the render process to complete itself. To pull that lost information into the visible world, we will need to increase the number of photons being used. Increasing caustic photons improves the definition of the caustics. Hit F10, open the Indirect Illumination tab and slide down to the very bottom. In the Global Light Properties area, increase the number of Caustic Photons to 50000 and Render. See below: