creatIng volumetrIc fIRE
In this section we will produce a fire simulation and show how to shade using Octane volume medium. You will see practically how both volumes work and what kind of settings are made when shading. We gave you a link below so that you can follow and practice.
Download the scene from here
IMPORTANT NOTE: The following example uses the TurbulenceFD plugin to simulate fire. However, you can also use other simulation softwares. For example, you can simulate fire in Houdini and export to Octane as VDB file. What matters is the shading settings you'll make in Volume Medium. First you need to make a good simulation. It is difficult to simulate a fire and fire is a very complicated phenomenon. To simulate this you need to advanced solver and options. So do not expect to generate realistic fire using Noise from the Generator.
MAKING FIRE WITH TURBULENCE FD
In this mini tutorial we will create a volumetric fire effect using TurbulenceFD. First, install TurbulenceFD in your system before opening the scene. Turbulence FD is a Cinema 4D plugin for fluid simulations. It produces realistic and beautiful results. You can buy it by going to Jawset's site. After installing the plugin, open the "fire_01" scene. You will not see any simulations because the fire cache file you see in the picture below is huge (124 GB) , so you have to generate this cache file yourself. Therefore, during the explanation we will show the fire setup then you will only cache. If you know Turbulence FD, you know how to cache it. If you are new to Turbulence FD, there are both commercial and free tutorials on the Web. You can watch and learn. However, free tutorials do not fully explain such a complex simulation software. So, we recommend you buy and learn from a professional tutorial. It's worth it.
Now we will produce the fire setup you see in the picture below. We will not explain the other cosmetic factors because they are already there. If you're ready, let's start:
01- Open the "Fire_01" scene. Create a container from Plugins / Turbulence FD and change the location and size as you see in the picture below. So we set the size of the voxel grid and placed it in the head of the Dragon. to fire the dragon's mouth and place it in the head of the dragon. You can increase the Voxel size to 7-8 instead of 3, at least make the TFD run faster for preview simulation until the final cache. Then you can go back to value 3 again. The quality of the simulation increases as you decrease this number. However, you spend a lot of simulation time and huge cache files. You can also crash the software at very low numbers. Be careful.
02- Now let's assign the Emitter object to Turbulence FD, which stands in Dragon's mouth. To do this, select the "Emitter" object from the Object manager, right click on "Turbulence FD tags" and select "Turbulence FD Emitter". Change the parameters as you see in the picture below. We will spread fire from this emitter object. For now, we will not use collision for the Dragon head.
03- Set the Timeline duration to 300 frames and select "TurbulenceFD container" from the object manager. Now that there are a lot of settings here, change the parameters as you see in the pictures below.
04- Now that we've done these settings, let's look at how the dragon fire from the viewport. To do this, first select TurbulenceFD container from object manager and go to the cache tab from the container tab. From here, press "New" and select a fast hard drive (SSD if possible) to save the cache file. Then go to TurbulenceFD from the plugins menu and select "Simulation Window". If you click the cache button you can see the other options. You can use CPU or GPU for caching. Choose one. After making the settings here, press "start" and wait for it to finish.
05- Once the simulation is finished, you can easily play it in the viewport. If your settings are correct, the result will look like the picture below.
06- Go to the desired frame (eg 265) and select "TurbulenceFD Container" from the object manager. Right click and assign an Octane Object tag. Go to the Particle rendering tab in the Object Tag settings. If it is not active, select "Voxel" from Enable. The "Voxel" option here is written to work only with Turbulence FD. There are a few options here. "Voxel size" is for to set the voxel quality again. "Abs / Sct." channel will be used in the Volume medium, therefore the Absorption and Scatter properties will be used for which channel in the simulation. "Use motion blur" is for simulating blur. But for that you need to cache the velocity channel in Turbulence FD. Without Velocity, motion blur does not work. "Velocity scale" increases motion blur effect.
Volume medium is the part we are mainly interested in. From here we will make the Dragon fire shading. Now, set the Voxel size to 2, abs / sct and the emission channels to "temperature".
07- Now click on Volume Medium and change the parameters as you see in the pictures below.
08- Now run Live Viewer. If you have done everything right, you will get the following result. As you can see in the picture, it has been given a relatively low density to make the fire bulky. You can also make this fire thin by playing with the density setting in the same way. Volume Step lenght is the most important setting. Here you determine how much of the distance between voxels can be covered. In the event of a fire, you can lower the value to make it more detailed. Do not decrease too much because you can get a solid look. Of course, all of these settings work in conjunction with all other settings. So make a lot of practice.