Caustic sampler tutorial

[3dpoder]

caustic sampler tutorial
Daniel labarge


[fig. 5] author: Daniel labarge [prince]
Website: id Studios [www.intellidesign.org]
Email: labarge@intellidesign, org.

Occupation: graphic artista & web programmer.

In this tutorial we are going todo experiment with Yafray and Blender and learn how they interact together. We Will create a simple caustic effect using default settings. Further experimentation can be used todo create breath taquíng imagery.
getting started.

First, we Will ned todo have the latest versións of Blender [blender 2.41] and Yafray [Yafray 0.7] both installed on your computer. You can get these from www.blender.org and www.Yafray.org respectfully. Once installed you Will be ready todo begin rendering your first Caustics.

Using Caustics.

The setup of the scene is very simple. We Will be using the default scene with some Lamp placement changes.
1. Launch Blender.
2. Go todo the render buttons [f10] and switch the renderer from Blender internal todo the Yafray renderer.

This Will create some new panels in the render buttons, edit buttons, material buttons, and the Lamp buttons. We Will get todo these new panels shortly.
3. In the 3d window select [RMB] the default Cube. Go todo the material buttons [f8]. The Raytracing panel introduces for available Yafray features. We Will be making a clear Glass using default settings for Glass in material panel. Select clear Glass from the drop down menú. Set the remainder of your material settings todo fig. 1. You might want todo bevel the edged of the Mesh. For this object i used subdivide multi 3x and then added a 0.100 bevel 2x and then applied set smooth. A basic bevel would work just as well.


[fig. 1].
4. In the 3d window switch todo top view [num7] and add [spacebar] a plane [add>>Mesh>>plane] todo the scene, this is going todo be the flor in the scene, exit Edit Mode [tab]. You Will ned todo move [g] it down along the z-axis [z] one grid unit [hold Control] so that it is Flush with bottom of the Cube. Open the transform properties panel [nkey] and scale the plane todo 50 units or Simply press [s] and scale it todo spread up to the Camera view. Go todo the material buttons [f8] and add a new material. Make sure todo have the traceshadow característica enabled in this material. You can Even apply a texture if you like. I used a light blue solid color for this material.
5. In the 3d window switch todo top view [num7] and select [RMB] the default Lamp and deleete [del] it. Now place your 3d cursor at appróximately 0,4,2 XYZ global coordinates. Press [spacebar] todo add an área Lamp add>>Lamp>>área. The Lamp should be automátically selected but if not select it and then bring up the transform properties panel [n]. Set the location XYZ coordinates todo 0,4,2 respectfully in the transform panel. Set the rotation XYZ coordinates todo 65,0,180 respectfully. In the material/Lamp buttons set the power todo 0.250. Give it a shape of square 3.0. Set the shadow samples at 10 or greater.
6. Duplicate [shift+d] the área light then cancel [RMB] the auto-Grab function. This Will place the duplicated área light at the exact location of the original área light. In the material/Lamp buttons change the Lamp type todo Photon Lamp. In Blender only bien todo generates Caustics in the scene is using this Lamp. Change the Photon settings as in fig. 2.


[fig. 2].
7. Now switch over todo render buttons [f10] and change these settings as shown in fig. 3.


[fig. 3].
8. Render [f12] the scene.


[fig. 4].

Your results should be similar todo fig. 4. If your render doesnt match it try todo match closely the settings as given earlier in the figures. For you r help you can a los look at the example Caustics, blend file if you cant figure it out.
what just happened? .

Now that we have generated a god example of Caustics, now we are going todo look at how did the caustic worked in this scene and what else option s are available in the Blender interfaz. There are thre panels in Blender interfaz that contain settings for caustic:
The first one is the Yafray panel itself. This panel allows you todo control the Yafray renderer settings. Normally it god enough todo just disable xml so that you can se the interactive rendering. Alos you can leave auto-a enabled todo let Yafray automátically control the anti aliasing option. For detailed control of Caustics you Will have todo switch todo manual anti aliasing setting though.

The second panel is the Yafray GI panel. Gi stands for global illumination. Global illumination is the effect that light is being emitted from a global light source. For this experiment we used the full type GI and set the quality todo high for better results. The other settings and are depth and cdepth. Depth is the distance that Yafray calculates a single ray during Raytracing. The smaller the value the quicker but less accurate the Raytracing Will be. Cdepth is similar but it is for Caustics Photons in the scene. Again the smaller the value the quicker but less accurate the Caustics in the scene Will be. We a los enabled Photons in this panel. This Will enable GI Photons which are a los referred todo as helper Photons. They then are emitted from all of the lights in the scene. The more Photons (we used 100,000) better the results, but this Will a los exponentially increase the rendering time.

The last panel is the Lamp panel[f5]. This is located in the material/Lamp buttons. You Will ned todo select the Photon Lamp in the scene todo se the Yafray shadow and Photon tab. By enabling Photon Lamp we enable the use of Photons for the Caustics from a direct source. Here the power setting is like any other light and tells how bright the Caustics Will be. This Photon Lamp allow us todo direct the direction of caustic and optimize the Caustics results nicely. We used about 100,000 Photons here. For some complex scene it can go all the bien up to a million. It just depends on how much computation you want todo do. You can experiment with the other settings as they usually require some testing but default settings Will usually achieve god results regardless.
extending Caustics.

Caustics are not restricted todo transparent materiales either. You can use Caustics for metallic materiales to, just remember that two metallic materiales Will a los reflect the Photons so they generally Will not show up some times.

To finish up this tutorial ill give you some suggestions todo play around with:
Try adding a texture or a color todo the Cube and giving it some Nor or displacement, replace the Cube with a sphere or another Mesh, use several Photon lamps. Have your super clúster handy, use an HDR global texture, email me your experiments. Id love todo take a look at them.

Daniel labarge.
www.blenderart.org.
.