Cinema 4D + VRAY Tips and Tricks #2

C4D + Vray ANTIALIASING (Chaos Group)

Antialiasing is one of the most important things for good digital produced images or animations.Vray has one of the best and most robust AA solutions available. In VRAY the antialiasing again is not just a thing that gets applied after shading but the whole engine is connected to the image and DMC Samplers.

The same power that gives the GI engine its quality is also used for Images sampling. Therefore sometimes image sampling (Antialiasing) is used in vray also to support GI and glossy reflections. so all setup is party connected, specially the adaptive DMC method.

Why do we need AA in renderings? - in real word cameras or in the human eye the light goes through more or less perfect lenses. those lenses and also the air filter the light and compensate extreme contrast between near points. also analog methods are not bound to pixels and therefore do not have to problem of pixel stepping when images do not have enough resolution or of very tiny and fine structures have to be rendered.

Vray can render ultra fine lines, by oversampling an image in an intelligent and still fast way. for areas that don`t need much antialiasing vray can use under sampling - negative values - at the same time, depending on the method, this highly adaptive AA can give ultra crisp and still still soft results at reasonable render times. i believe one aspect of the high image quality in vray is not only the great GI engine but also the wonderful AA quality.

In vray you can use values like 100x AA with Adaptive DMC Sampling (with universal setting p.e.) and still get ok render times. such extreme values wont be used all time, but they show the power behind. still high settings like 4x16x can be used at ultra high speeds for superb image quality. also i noted that images with good AA can be scaled up much better than “normal” 3d images, so it might pay to invest in learning the AA engine and use good quality settings.

In VRAYforC4D, an image sampler refers to an algorithm for sampling and filtering the image function, and producing the final array of pixels that constitute the rendered image.

  

VRAYforC4D implements several algorithms for sampling an image. You can choose between Fixed rate sampler, Adaptive DMC sampler and Adaptive subdivision sampler. Which is the fastest depends very much on the scene and on the settings of GI, Materials etc.

Parameters

Image sampler

Type - specifies the image sampler type:

Fixed - this sampler always takes the same number of samples per pixel;

Adaptive DMC - this sampler takes a variable number of samples per pixel depending on the difference in the intensity of the pixels;

Adaptive subdivision - this sampler divides the image into an adaptive grid-like structure and refines depending on the difference in pixel intensity.

Antialiasing filter

Various filter can be applied, there are sharpening methods and blurring filters, depending on what you need. for still images you might want to use sharpen filters,for animation make sure to use soften filters!

Fixed rate sampler

This is the simplest image sampler, and it takes a fixed number of samples for each pixel. 

Subdivision - determines number of samples per pixel. When this is set to 1, one sample at the center of each pixel is taken. If this is greater than 1, the samples are distributed within the pixel. The actual number of pixels is the square of this parameter (e.g. 4 subdivisions produce 16samples per pixel).

Note:  that due to clamping of samples to the [black, white] range for the RGB color channel, sometimes this sampler can produce darker results when used with blurry effects. The solution in this case is to increase the subdivisions for the blurry effect, or to use the Real RGB color channel..

Adaptive DMC sampler

This sampler makes a variable number of samples per pixel based on the difference in intensity between the pixel and its neighbors. 

This is the preferred sampler for images with lots of small details and/or blurry effects (DOF, motion blur, glossy reflections etc). It also takes up less RAM than the Adaptive subdivisionsampler.

Note:  that due to clamping of samples to the [black, white] range for the RGB color channel, sometimes this sampler can produce darker results when used with blurry effects. The solution in this case is to increase the subdivisions for the blurry effect, or to use the Real RGB color channel..

Min subdivision - determines the initial (minimum) number of samples taken for each pixel. You will rarely need to set this to more than 1, except if you have very thin lines that are not captured correctly, or fast moving objects if you use motion blur. The actual number of pixels is the square of this number (e.g. 4 subdivisions produce 16 samples per pixel).

Max subdivision - determines the maximum number of samples for a pixel. The actual maximum number of sampler is the square of this number (e.g. 4 subdivisions produces a maximum of 16samples). Note that VRAYforC4D may take less than the maximum number of samples, if the difference in intensity of the neighboring pixels is small enough.

  

Threshold - the threshold that will be used to determine if a pixel needs more samples.

Adaptive subdivision sampler

This is an advanced image sampler capable of under sampling (taking less than one sample per pixel). In the absence of blurry effects (direct GI, DOF, glossy reflection/refraction etc) this is the best preferred image sampler in VRAYforC4D. On average it takes fewer samples (and thus less time) to achieve the same image quality as the other image samplers. However, with detailed textures and/or blurry effects, it can be slower and produce worse results than the other two methods.

Also note that this sampler takes up more RAM than the other two samplers - see the Notesbelow.

Min. rate - controls minimum number of samples per pixel. A value of zero means one sample per pixel; -1 means one sample every two pixels; -2 means one sample every 4 pixels etc.

Max. rate - controls maximum number of samples per pixel; zero means one sample per pixel, 1 means four samples, 2 means eight samples etc.

Jitter - displaces the samples slightly to produce better antialiasing of nearly horizontal or vertical.

  

Threshold - determines the sensitivity of the sampler to changes in pixel intensity. Lower values will produce better results, while higher values will be faster, but may leave some areas of similar intensity under sampled.

Object outline - this will cause the image sampler to always super sample object edges (regardless of whether they actually need to be super sampled). This option has no effect if DOF or motion blur is enabled.

Material ID - uses the material id pass (change of material) to antialiasing the transition from one to the next material on surface.

Normals - this will super sample areas with sharply varying normals. This option has no effect if DOF or motion blur is enabled.

Normals threshold - this will super sample areas with sharply varying normals. This option has no effect if DOF or motion blur is enabled.

Z-Value - uses the z-depth pass (change of depth) to super sample the areas where a sudden depth change occurs.

Z-Value threshold - adjusts the threshold of the above depth sampler.

 Notes

• Which sampler to use for a given scene? The answer is best found with experiments, but here are some tips:
  
  • For smooth scenes with only a few blurry effects and smooth textures, the Adaptive subdivision sampler with its ability to under sample the image is unbeatable.
    
  • For images with detailed textures or lots of geometry detail and only a few blurry effects, the Adaptive DMC sampler performs best. Also in the case of animations involving detailed textures, the Adaptive subdivision sampler might produce jittering which the Adaptive DMC sampler avoids.
    
  • For complex scenes with lots of blurry effects and/or detailed textures, the Fixed ratesampler performs best and is very predictable with regards to the quality and render time.
    
• A note on RAM usage: image samplers require substantial amount of RAM to store information about each bucket. Using large bucket sizes may take a lot of RAM. This is especially true for the Adaptive subdivision sampler, which stores all individual sub-samples taken within a bucket. The Adaptive DMC sampler and the Fixed rate sampler on the other hand only store the summed result of all sub-samples for a pixel and so usually require less RAM.

Cinema 4D + VRAY Tips and Tricks #1

Hello dear readers. In rendering, the most crucial part of it is how to put up your rendering settings with all the right amount so your 3D models would look realistic (since that's the goal here). :-)

First and foremost we will define each and every single term here (Vray : Chaos group), so you may understand sometimes most of what I'll be talking about.

Geometry 

Displacement - enables (default) or disables VRAYforC4D's own displacement mapping. 

Scene units - here you can setup scene units, it madded for quick setup, and to save parameters with file. 

Lighting

Lights - enables or disables lights globally.

Hidden lights - enables or disables the usage of hidden lights. When this is checked, lights are rendered regardless of whether they are hidden or not. When this option isoff, any lights that are hidden for any reason (either explicitly or by type) will not be included in the rendering.

Shadows - enables or disables shadows globally.

Show GI only - when this option ison, direct lighting will not be included in the final rendering. Note that lights will still be considered for GI calculations, however in the end only the indirect lighting will be shown.

Photometric scale - this parameter allow to compensate exposure for non physical camera renders.

Indirect illumination

Don't render final image - when this option is on, VRAYforC4D will only calculate the relevant global illumination maps (photon maps, light maps, irradiance maps). This is a useful option if you are calculating maps for a fly-through animation.

Materials 

Reflection/Refraction - enables or disables the calculation of reflections and refractions in VRAYforC4D maps and materials.

Max depth - enables the user to limit globally the reflection/refraction depth. When this is unchecked, the depth is controlled locally by the materials/maps. When this option is checked, all materials and maps use the depth specified here.

Maps - enables or disables texture maps.

Filter maps - enables or disables texture map filtering. When enabled, the depth is controlled locally by the settings of the texture maps. When disabled, no filtering is performed.

Max transparency levels - this controls to what depth transparent objects will be traced.

Transparency cutoff - this controls when tracing of transparent objects will be stopped. If the accumulated transparency of a ray is below this threshold, no further tracing will be performed.

Glossy effects - this option allows the user to replace all glossy reflections in the scene with non-glossy ones; useful for test renderings. 

Override material - this option allows the user to override the scene materials when rendering. All objects will be rendered with the chosen material, if one is selected, or with Default surface color materials if no material is specified.

 

Overriding material- this option allows to choose material that will be use for overriding scene materials. Just drag and drop here vray material from Materials Manager.

Default surface color - color that replace all the scene materials when rendering.

Raytracing

Secondary rays bias - a small positive offset that will be applied to all secondary rays; this can be used if you have overlapping faces in the scene to avoid the black splotches that may appear. 

Geometry back face cull - enables or disables (default) back face culling for camera and shadow rays. When this option is on, the surfaces of objects which are turned away from the camera (or the light source, when tracing shadows) will appear fully transparent. This allows to look inside closed objects when the camera is outside.

Cinema4D Volumetrics Effects

Volumetric Effects (experimental) - turning this option on will allow you to use Volumetric Effect on Lights in VRAYforC4D. For use it you must also enable it in Cinema4D Light Common Options. 

  

Miscellaneous options

Optimized atmospheric evaluation - turning this option on will cause VRAYforC4D to first evaluate the atmospheric effects, and shade the surface behind them only if the atmospherics are sufficiently transparent.

Low thread priority - turning this on will cause VRAYforC4D to use threads of lower priority when rendering.

Stamp Vray informations - the frame stamp is a convenient way to put some short text over the rendered images. It can be useful in many ways - for example, in network rendering, to quickly determine which frames were rendered by which machine. The frame stamp is one line of text, which appears at the bottom of the image.

Total Triangles - the number of unique intersectable primitives, such as a triangle, generated for the current scene.

Label - here you enter the text you wish to appear in the images.