Rendering the animation
Importing the liquid into Cinema4D
Once the simulation is completed and the liquid dance looks good, it is time to render. So we can go back to Cinema4D and finish the scene setup. The scene I used for the movie is available for Cinema4DR10 LINK (right-click). For the front-side of the cube I just selected the polygons and deleted them, the liquid stays inside anyway... The mesh loader plugin from NextLimit will import the meshes created during the simulation. Set the file path for the mesh-bins in the ".bin File Sequence"-setting of the plugin options by selecting the first mesh-file on the harddisc. Maybe you have to adjust the lenght of the animation in the timeline according to the amount of frames created and saved in RealFlow. You can always add more steps in the simulation (simply increase the "Frame End" and continue the simulation) and those new bin-files will be exported with a file name corresponding to the frame number.
The light setup in Cinema4D
I have used two lights in this scene. One is an omni-light called "filling" which is sitting close to the ceiling of the box. And the other one is "caustics" which is a spot light targeted at the center of the box. This light should provide the caustic reflections caused by the surface of the liquid droplets. Actually, you could exclude the Cube in the "scene" settings of this light source, so only the caustics appear but not the reflection of the spot itself at the walls of the box. Caustics require the advanced render module of the Cinema4D-package.
Personally, I like Caustics very much, but they increase rendertime and can create problems, if the settings of materials and lights are not balanced. It can happen, that you see a lot of single spots instead of sparkling lights. In my experience, the most important parameter for good caustics is the number of photons from the light source and the "Radius" setting in the illumination channel of the material that should receive the caustic light. The sampling parameters on the materials are less important. Of course, you have to turn on caustics in the render settings in order to see them (100% surface caustics) and they need to be recalculated freshly for every frame. The volume caustics are meant for visible light. This is not needed here and should be deactivated, otherwise the rendering times explode.
I often apply a "Polygon Reduction" deformer from the objects menu to the imported mesh. This reduces rendering time but it is a pain during the playback of the meshes in the editor. Therefore, I turn it off when working on the scene (as on the picture) and just turn on before rendering. The cube has a standard nukei shader on it. There are some smaller changes, including the illumination setting to make the caustics sharper (smaller caustic radius and more samples):
This is my water material for project (above). I have tried to keep it as simple as possible in order to reduce rendering times. There are many variants of water materials possible, for example with additional wavy-roughness, some percent of fog, HDR-environment, translucent materials or ambient occlusion. It is a wide field of experimentation. In the render settings you can specify a folder where completed images will be stored, or render directly to a movie.
The scene file for C4DR10: scene
An example of many possible project setups for RealFlow4 (without exported data): project
For questions: Email
Have Fun !
Christian Z.
first version January 2006, updated for RF4 June 2007, and for the
latest program versions in August 2008
