Redshift for Cinema 4D: TFD fluid rendering
Redshift for C4D
Cinema 4D is also very powerful in producing TFD fluids. Below Fox Renderfarm, the powerful and affordable render farm in the CG industry, will show the effect of Redshift rendering TFD fluids.
In Redshift 2.6.43, when performing real-time preview and TFD calculation, sometimes Cinema4D software crashes. One solution is to restart Cinema 4D software. To adjust and solve the fluid in the default state without Redshift preview. When done, open Redshift Preview again. If you want to resolve the fluid during this period, to avoid Cinema 4D crashing, you must restart Cinema 4D.
Because TFD (Turbulence-FD) is compatible with Cinema 4D and can preview the fluid and model interaction in real-time, TFD is almost the first choice for fluid simulation in Cinema 4D. With Redshift, the smoke of the TFD can be illuminated by the scene light, and if it is a simulated flame, the flame itself can provide a true global light illumination effect as a light source.
Lighting smoke requires adding Redshift lights and increasing the Contribution Scale in the Volume tab of the lights. At the same time, add the Redshift Volume material to the TFD Container.
To render a flame with smoke, you need to set the Scatter and Emission channel sources in the Volume material.
How to render TFD smoke fluid
As shown above, there is a solved TFD Container in the scene. Because it is only intended to simulate smoke, only the Temperature channel is opened in the TFD. And the whole scene only uses one Dome Light for lighting. If you want the smoke fluid to be illuminated by the same light source, then you need to increase the value of Contribution Scale under the Volume tab of Dome Light. The higher this value, the more the fluid is affected by the light source.
Create a new Redshift Volume material and point it to the TFD Container. Volume material is also very simple to take, no additional nodes are needed, all settings can be done in Redshift Volume.
For smoke (non-luminous), the most important are Scatter and Absorption. These two parameters need to be adjusted at the same time.
Comparative image of 2 parameters in the official document
In the Volume node's Advanced tab, you can adjust the overall transparency and projection of the fluid.
In this case, if you want to simulate the light and thin smoke, so lower the New Max in the Density Remap Range, the following is a comparison chart.
During real-time preview, the fluid is displayed as dots. It is recommended to perform regional rendering and bucket rendering to observe local fluid details. The parameter that affects the noise of the fluid is mainly the light source that illuminates the fluid (you need to increase the Samples under the Volume label). Therefore, you can increase the sampling of the light source.
If you render the fluid separately, you can use the Denoise noise reduction that comes with Redshift, which will be faster.
How to separate smoke fluid
Unlike ordinary materials and models, Redshift cannot separate fluids through direct AOV. However, the separation effect can be achieved indirectly by separating the lighting effect of the fluid or rendering the fluid alone on a black background.
Add Volume Lighting to AOV Manager so that the lighted part of the fluid can be output separately.
Volume Lighting effect, the disadvantage is that if there is occlusion in front of the fluid, the resulting smoke effect will be incomplete. It is recommended to render the fluid separately.
Separate rendering method: Group other models except fluid, add Redshift Object tags to the group, check Override in Visibility, cancel Primary Ray Visible. This can hide other models, and retain the scene model's interaction with the fluid.
Render smoke effects separately
How to render flames and smoke
A simple burning effect was made using TFD. Because the flame and smoke are to be rendered at the same time, both Temperature and Density in the TFD Emitter must be given certain values.
On the left is the Temperature channel and on the right is the Density channel
The scene has a special area light to illuminate the smoke part of the fluid.
Scatter and Absorption mainly control the smoke part, and Scatter's Channel is set to TFD Density. Emission controls the flame part, and Channel is set to TFD's Temperature. Scatter controls the flame brightness, the bigger and brighter. Emission Remap Ramp maps the specific color of the flame, and the left side of the gradient bar corresponds to the low temperature. Click to adjust the prefab, there are common flame swatches.
Because the flame itself is a light source, this flame also produces a global light effect.
How Redshift for C4D to accelerate rendering while noise reduction
Redshift for C4D
Noise reduction has always been a problem in rendering, so how to use the Redshift for C4D to denoise while speeding up rendering. As the leading cloud rendering service for 3D Animation and Visual Effects, Fox Renderfarm brings tips, hope to help you accelerate your rendering while noise reduction.
The principle that Redshift can denoise and render faster is that the number of samples can be increased in places with more noise, and the number of samples can be reduced where it is not important or not easy to generate noise. And this sampling allows the user to customize, which is also the origin of the name of the biased renderer.
The most powerful part of Redshift is the ability to speed up rendering while reducing noise, which is difficult for most renderers. However, Redshift acts as a slightly deviating renderer, allowing the user to adjust the sampled values of various effects (such as reflections, SSS, lighting), and with Unified Sampling (let the renderer determine if it needs to sample more) to avoid wasting resources. But the disadvantage is the same: if you don't adjust the parameters, the advantages of Redshift will not work.
The graphics card used in this article is the RTX 2080TI XTREME, and the scene shown in the rendering case, it is 1920*1080 pixel format. using this method has cost 10 minutes and 57 seconds, also has a lot of noise. After 9 minutes and 15 seconds of improvement, the noise was significantly improved.
Overall conclusion: Turn off special effects such as depth of field and motion blur, reduce the total sampling, and adjust the sampling values according to the possible positions of noise. Check the noise distribution with the AOV layered channel for a clean picture and fast rendering.
AOV layered channel checks for noise location，
Before adjusting, just adjust the Samples Max to 2080 in Unified Sampling. On the final picture, you can see significant noise on the windows and the ceiling.
Now start to denoise. First reduce the Samples Max of Unified Sampling to 16, so that you can see the effect of modifying the parameters more intuitively.
This is the GI setting unless the scene is very complex, the Primary GI Engine has chosen Cache, and the noise is relatively less.
In the AOV panel, the above items have been added to check for noise. Note that the lights need to be set in the Light Groups. The red box above shows the Dome light channel.
Beauty channel, a lot of noise
GI channel has almost no noise
Reflections reflection channels are all noise
Reflections refracting channels with very much noise
Dome light channel, all noise
The layer of noise is now checked and can be debugged separately. Mainly reflective material, transparent, and lighting. After the adjustment, use Bucket Rendering to output the final image quality and render again. After watching the effect, adjust the effect again.
The material's reflection sample is adjusted to 256 or 512, visible in the Reflections channel, and the reflection is significantly cleaner. There is noise on the glass and you can continue to increase the sampling.
Next, the Reflections transparent sampling is increased by 2048. Although there is noise, it has been significantly improved.
All the values are debugged, return to AOV to check the noise, and then final rendering.
If there is blurry depth of field and motion blur, Samples Max needs to be a little bigger, because the two blur effects have no special sampling parameters, and blurring requires more light to reduce noise. This is adjusted to 2048.
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