In this Tutorial We are going explore some of the essential things when it comes to creating V-Ray materials , what we going to be discussing here is hopefully going to get you started making V-Ray materials and again , some more in depth tutorials are going to be available for specific parts that are not covered in this series
V-Ray materials are not as simple as the standard materials , the way they behave is more physical ( as surfaces can absorb light , refract it , reflect it .. etc ) and for that reason , each parameter is tight another and colors play a huge role in this regard .
VRay has a number of material types which can be used in combination or separately to produce high quality renders . The main materials that we are going to be working with is the V-Ray Advanced Material .
V-Ray Advanced Material
The Advanced V-Ray material is arranged in layers , each layer has its own options and most of them have a transparency option ( or a mask ) that can be used to mix between the layers , and just like in photoshop , we need a gray map or shader to be used as a mask .
General Options :
- Gamma : adjusts the gamma of the material preview but has no effect on the actual material
- Overridable : you can uncheck this option if you don’t want a specific material to be overtaken by the override option in the general options ( render settings )
- MltID Color : define the color ID of each material , will appear when using the material ID with the multipass
– Material Weight
This is the alpha option in the vray advance material , you can use gray shaders or textures to delete specific parts from an object in the render time
The options for this layer are fairly easy to work with , the Invert option will invert the blacks and whites of your textures or shader , and the Mix Strength defines the amount of this material when it’s combined with other materials ( when mixing materials with the blend material for example )
- Notes : Any invert option in other layers is going to do the same thing . and its only meant to work gray textures so its best not to be used with normal maps
Bump and normal maps add sense of depth to renders on individual objects , both can be used via this layer by changing the type .
- Bump Shadows : Enabling this parameter is going to provide better looking shadows . its recommended to keep it off ( especially when using V-Ray dirt )
- Bump Delta Scale : This parameter can be decreased to sharpen the bump and Increased to blur it
- Bump amount : The bump amount in scene units
– Luminosity Layer
The luminosity layer can be used to make an object ( polygonal surfaces ) emit light , it works with the default color or with textures and shaders it also has the transparency slot so we can mix it with all of the layers beneath it ( tested with v22.214.171.124 and it seems that it doesn’t work , all other layers transparency options work just fine ). lets explore some of its options
- Color : When there is no texture being used , this is going be used as solid color for the light
- Color Amount : This is the intensity of the illumination for the color ( ignored when direct light is enabled )
- Texture Amount : When a texture is being used this defines the illumination of it ( also ignored when direct light is enabled )
- Double Sided : This option determines whether the light is going to be on each side of a normal or not
- Compensate Exposure : This option adjusts the intensity when using a Physical Camera , its ineffective when using the direct light option but very useful the majority of the time so keep it on .
- Direct illumination : Converts the objects of the material into actual lights with area shadows , the parameters of direct light are similar to an area light ( then intensity will be overridden by the direct light intensity so adjust that instead )
– Reflection Layer
The reflection layer is like simplified version of the specular layer , without any specular option it can only be used to provide sharp reflection , the recent versions have added a fresnel option to so it has its applications sometimes but most of the time , we use the specular channels with high fresnels for sharp reflections and over time you will use this layer less . will discuss the options of the specular layer since they very similar and the concepts can be similar in regards of the options .
Before we talk about the specular layer , the transparency option for this and other layers after it work fine so this an example of how the transparency solution should work with gray shaders or textures ( note the slight reflection in the orange area is specular layer reflection )
– Specular Layer
In the real world , the majority of surfaces have ceraint a amount of reflections in them , the reflection however is much more visible with non-glossy ( or non blurry ) surfaces such as car paints and mirrors and other types of optics / surfaces . There is also to a high degree that all reflective surfaces have also fresnel , and it is the amount of reflections can be seen from an angle , Very reflective surfaces ( like mirrors ) have a high fresnel numbers and the therefore the reflection visibility is the same from any angle the surface is viewed from .
Highlights on the other hand are the reflection of the illuminations source whether its small bulb light or a large window on a bright day , the size of the them depends on the size of the light source , V-Ray also however provides another non real ( fake ) highlights ( named specular highlights ) . We have the choice of keeping everything physical and only depend on reflections on for the highlights or we can use the specular highlights to speed things up or make a mix of both !
With all this in mind , the real question we need to ask is really what are we after ? , The simpler answer is that if you have have time to render high quality physically accurate images then that is possible and also you can go non physical and still get a similar enough ( to the physical one ) result that you can work with at the end with specular highlights . Keep in mind that vray is actually is very fast in calculating rough reflections and also has some good interpolation methods to speed things up even more , and as a general advice try to minimise the the use of the fake highlights .
Before we look at some of parameters and what they do in the specular layer with some samples , you probably noticed that we have not one , but 5 layers of the specular layer and that is one of the advantages of VRayforC4D in our opinion because we can mix different layers to produce some specific materials .
- Specular Type : lets keep it simple and say use only Blinn and Ward , Blinn is for glossy ( very reflective ) surfaces and Ward is for more rough surfaces
- Specular Color ( and Texture ): defines the color or texture of the specular ( it does not control the intensity of the reflection , it only changes the color , unlike other v-ray versions the intensity is either controlled by fresnel or the Transparency options )
– Specular Layer Parameters
Lets talk about the options in the lower section first
- Glossiness Subdivs : sets the quality of the glossiness or blurry reflections , higher values will render slow but with great quality and vise versa . you can leave at the default value of 8 and relay on the dmc for better quality or just edit it individually here
These test renders really show how the subvids parameter can improve the quality of blurry reflections , but as you can see , the increasing render time was a big factor too , so in the last image you can see that we are saving a lot time by using the light cache ( Interpolation ) to solve the blurry surface , the only disadvantage tho is small artifacts caused from that . These can be solved by using the Fixed filter type and use 3-4 times the light cache sample size as the filter size !
**Update : Use the light cache retrace with lower thresholds to solve the artifacts !
- Back side : when its on , it will calculate the specular layer on the other side of the polygons ( normals ) as well
- Cutoff : the threshold number for tracing the specular layer , best not to be set to 0.0 or kept on 0.01 , lower values like 0.003 are recommended to prevent the harsh cutoff of reflection when its very minimal
- Trace Reflections : determines whether reflections will be traced or not .
- Trace Specular : determines whether speculars will be traced or not.
- Trace Depth : the number of times the reflections and specular will bounce
- Exit Color : the color represented after the reflections stop bouncing
- Refl Dim Distance : this determines whether to use the dim distance or not , its basically killing the reflection tracing based on certain distance
- Dim Distance : the distance until the tracing is topped
- Dim Falloff : a fall off radius for the dim distance
Now lets talk about the some of the more main settings for the specular layer, the best way to look at them is to treat them as three separate categories . The first is the specular highlights options , the second is for the reflections , the third is for the special effect Anisotropy . Keep in mind that Each parameter can be controlled by a pre-calculated textures or shaders for the reflections ,highlights or with a straight given value or even with both .
- Highlight Glossiness : determines the shape of the highlights , higher values will produce smaller highlights and the other way around .
- Reflection Glossiness : detriments the blurriness or sharpness of the reflections , higher values will produce sharp reflections and the other way around .
Next : What is Anisotropy ?
There is really extensive articles about the thing itself in very technical manner , but it propply easier to understand if we knew how does it comes to be in real life .
Anisotropy occurs with brushed surfaces finished in a particular way . some special materials ( or tools ) are used to create either a clean and straight brushed surfaces or a circular ones with more effort . ( Image source link , Image source link 2 ) .
In v-ray we can tell our reflection material about the brushing using the reflection textures ( brushed ) and we can also define how an entire surface is brushed and or only some areas using the rotation parameter ! ( this paragraph in short : it can be done with v-ray :) )
so hopefully this makes sense , now we need two things to simulate this effect , a brushed surface and another texture to define the pattern . making these textures can be easy using photoshop , but will cut through to material part using the already made textures ( both brushed and rotation patterns ) .
To make a brushed surface , simply apply the material in each of the glossiness parameters ( reflections and highlights ) and adjust the mix strengths for the desired look , NOTE : that this not a procedural texturing and therefore make sure the have good UV’s and best if you used a standard Cinema 4D material to see how the brushed texture is going to look like and then apply the vray material on top of the texture tag .
The brushed metal look effect can be achieved by increasing ( or decreasing ) the Anisotropy Parameter
Now lets define the pattern for vray , and these particular shapes can by brushed in total so a simple gradient will do for it ( added in the rotation slot )
Lets do some more complicated patterns , as the gentleman above ( links ) did , we also have create the rough reflection maps for the patterns and also the rotation maps for the Anisotropy effect . take a look at those examples and experiment with provided files
As mentioned before , the fresnel is one of the essential properties for nearly any surface in real life , this means that we should enable and use the fresnel for any material , alternately using a fresnel shader is also an option but its not recommended since the vray version of it is more accurate and provides a great deal of control too .
In the specular layer , the fresnel IOR value is used for the reflectivity curve and we can also adjust the reflectiveness of both 0 and 90 viewing angles using the colors , the black and white colors represent the transparency at which then the layer after the specular layer appears ( thats why when using the fresnel , the transparency is going to be disabled )
This is just simple representation of what the fresnel effect look like with different viewing angles
– Diffuse Layer
This is the base color or texture of the material . there is two of this layer so it can be useful to mix between them with transparency option , also with layer we can use V-Ray dirt which we are going to talk about in further tutorials .
Using this layer is in general pretty straight forward . use colors or shaders or textures as base color and/or mix between them if desired
– Refraction Layer
Refractive and translucent surfaces can be simulated using this layer , we can create glass , frosted glass , ice , water and others with this layer . lets explore some of the everyday-use parameters or options for this layer
- Index Of Refraction ( IOR ) : each type of translucent objects is a different medium in which the light passes through it , the Ior is the value that comes out of dividing the speed of light in vacuum by the given medium . here are some values for different kinds of objects ( mediums )
- Water at 20 C = 1.33
- Ice = 1.31
- Crown glasses = 1.52-1.62
- Diamonds 2.13
Use Exit Color : This option determine whether to use a custom color or not when the maximum reflection or refraction is reached , could be useful if wanted to use a custom color for some glass edges for example .
- Use Dispersion : enables or disables dispersion , this a more recent feature that has been added to vray , the effect can be seen in diamonds for example and its controlled by the abbe number . you can use this database to get the number for different types of objects .. as a general rule of thumb , the lower the abbe , the more the dispersion . here is an example ( click to enlarge the image )
- NOTE : Disable the sub-pixel mapping when using Dispersion !
Another example with caustics made a while back ( animation )
- Glossiness : this is the glossiness of the refraction , can be controlled by a value or shader/textures .. you can combine a colored textures with its roughness map ( gray ) in this slot to create interesting surfaces .
Some surfaces in real life have different a appeal to them because of the they are created , grown .. etc . like tree leafs , papers , and some fabrics . Replicating these types of surfaces in v-ray can be done with two sided materials because it gives the translucency feel to the surface . so use them whenever you are using thin surface similar to the mentioned
Hopefully this short intro to the v-ray materials can make it a little easier when creating v-ray materials , some parameters where overseen on purpose but feel free to ask or respond to this tutorial as always in the comments section or on facebook or twitter .
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