The forth lesson covers the wide range of materials and textures that come with V-Ray
- Library Materials – we will see how to fine tune the materials in the V-Ray Materials Library to match our needs
- New Materials – we demonstrate how to setup some of the most commonly used shaders like plastics, metals, glass etc.
- Procedural Textures – we will discover some of the procedural textures that come with V-Ray and see how they can be useful.
- Displacement – we will use displacement mapping to further enhance the way our shaders look
- Export materials to library – we will see how to save and reuse or share materials that we’ve created
You can download the lesson guide here.
Each section is annotated in the video. You can find scene files with the same names in the Lesson 4 folder. These were made so that you can start at any one of these stages and follow the steps in the video to the end.
V-Ray for Sketchup comes with an extensive materials library that can be used directly. Since some of the materials use textures it is necessary for the user to manually set up the tiling of the texture by either adjusting its size or changing the UV tiling as seen in the video. All materials in the V-Ray materials library can be edited which allows us to start with a material that is similar to what we need and then further adjust it to meet our needs.
In this section, we will shade our scene starting from scratch and using the Generic V-Ray material. This is the standard V-Ray Material which allows us to create a wide range of physically accurate shaders. You can use textures to control most of its settings like diffuse, reflection, refraction, glossiness etc. and add bump and displacement mapping. We will create materials like Paint, Metal and Glass and in the process, we you will be able to see how the main parameters of the Generic material work. The commonly used parameters are:
- Diffuse – this is the diffuse color of the material and it is used to create flat non-reflective like walls or carpets. Note that most materials in the real world however have at least a bit of reflectivity
- Reflect – specifies the reflection color of a material. Can be used to create reflective materials like metals.
- Use Fresnel – when this checkbox is enabled the reflections depend on the angle at which we are viewing the surface. This is used in simulating materials that have a thin transparent coat that also reflects, like plastics or varnished wood. Additionally, most refractive objects like glass reflect light in this manner. The effect of this parameter also depends on the Index of Refraction – IOR of a material, which is a physically measured value of how light is refracted by a material.
- Reflection Glossiness – controls the sharpness of the reflection. A value of 1.0 means perfectly clear reflections (like a mirror). Lower values make the reflections blurrier.
- Refract – specifies the color of the refractions. Note that in order to create materials like glass you also need to have Fresnel reflections enabled.
- Fog color – this parameter specifies the color of a refractive object inside its volume. It allows us to simulate the effect where thick refractive objects look less transparent than thin ones.
- Glossiness – specifies the sharpness of refractions. A value of 1.0 means perfect clear glass refractions and lower values make the refractions look blurrier i.e. frosted glass.
Some of the parameters like Diffuse, Reflect and Refraction are controlled by a color swatch. It is a good idea to avoid setting those to completely black or completely white as this is not physically accurate. Setting the Diffuse or Reflect to completely black means that the object reflects no light at all (it is a black hole) and setting those parameters to completely white means that the object reflects all the light back to the environment which is again impossible. Additionally, if you set the Diffuse to completely white this may lead to slow render times when GI with Light Cache is used. You may use black for Reflect and Refract if you want to create a material that is completely diffuse. But those parameters should never be pure white even for very reflective or refractive materials.
The Emissive material is used to shade objects which are supposed to emit light i.e. phone or tv screens, lights with a complex shape etc. The material settings are pretty straight forward but it is important to note that objects with this material do not shine direct light into the scene. This means that if we want the objects to illuminate the scene we require GI with very high settings
- Emissive Color – Specifies the color of the light. A texture can be specified as well.
- Intensity – Controls the strength of the light.
Two Sided Material
The Two Sided material is used to simulate thin translucent materials like paper, fabric, thin leaves etc. The effect of the material can be seen only when we have a direct light source behind the geometry and the geometry doesn’t have a volume i.e. it is a plane. The settings are very intuitive:
- Front – Sets the material to be used for front faces as defined by the object normals.
- Back – Sets the material to be used for back side faces as defined by the object normals.
- Translucency – Controls the transparency of the material. By default, this color is black (0.0), which means that only the Front material will be visible. Setting this color closer to white makes the material more transparent – more of the Back material is visible.
- Multiply By Front – When enabled, the Translucency is multiplied by the Front material.
Subsurface Scattering Material
The Subsurface Scattering Material is used to simulate materials like skin wax fruit etc. It has Diffuse, Sub-surface scattering and Specular (reflections) layers. This material is greatly affected by the scale of the geometry. That is why it has a Scale parameter which allows us to adjust the way it looks without having to scale our scene.
- Scale – allows us to adjust the scale of the shader so that we do not need to adjust the scale of the geometry. Increasing this value increases the SSS effect making the object more translucent.
- Index of Refraction – controls how light is bent as it enters the surface. The default value of 1.3 is suitable for water based materials like skin or fruit
- Overall Color – a multiplier that allows us to tint the material without adjusting its other settings
- Diffuse Color – specifies the color of the diffuse portion of the material.
- Diffuse Amount – a value to control how much the Diffuse Color affects the look of the material. When it is set to 0.0 the Diffuse Color has no effect and the look of the material depends only on the Subsurface Color and Scatter Color parameters.
- Sub-Surface Color – specifies the color of the material beneath the surface.
- Scatter Color – specifies the color of the scattered light inside the volume of the material. Brighter colors cause the material to scatter more light and to appear more translucent; darker colors cause the material to look more diffuse-like.
- Scatter Radius (cm) – specifies how deep into the object the light is scattered. Larger values make the material more translucent.
- Phase Function – controls the direction in which the light is more probable to scatter. Positive values make the light scatter forward into the volume of the geometry and negative values make the light scatter backwards. Forward scattering happens in water based materials like skin or fruit, while backward scattering happens in hard materials like marble.
The options in the Specular layer are the same as in the Reflection layer of the Generic material with the only difference being that you have a Specular Amount parameter which allows us to control the strength of the Specular layer.
This section covers the usage of procedural textures to control some of the parameters of the V-Ray Material. Procedural textures are textures that are generated using a mathematical description or algorithm.
Color Correction Map
The Color Correction Map allows us to color correct a texture (bit map or procedural) inside SketchUp. This can be useful when we need to fine tune the colors of a texture and we do not want to constantly switch between photoshop and SketchUp. Using V-Ray Interactive rendering and the color correct texture we can quickly get the result we need.
Noise Map and Bump
The Noise texture is commonly used in CG. It allows us to add some randomness to a parameter. In this case we use it as a bump map to add small detail to the wall. Bump mapping is a shading technique to fake small bumps and dents on the surface of our geometry.
In this section, we use Displacement mapping instead of Bump mapping. The difference between the two is that bump mapping is a shading effect - it changes the surface normals of the shaded point so that it looks as if there are dents and bumps but the original geometry remains unchanged. This is clearly visible if you look at the geometry at a steep angle, you will see that the surface is actually flat. Displacement on the other hand subdivides the original mesh into much finer mesh and then displaces the new faces based on the texture. This creates brand new geometry. The effect is much more accurate and looks much better than bump mapping but it is also harder to calculate as it requires more RAM (to store the new geometry) and more raytracing for all the new faces in the scene.
Export Materials To A Library
In this section, we cover the process of exporting a material to a library. This allows us to store materials that we often use or to share materials with coworkers.
This lesson comes with 2 Extra modules - Advanced Materials and Advanced Textures. For each module, you can find a scene file with the same name.
You can download the lesson guide here.
1. Advanced Materials
In this module, we go over some of the less commonly used materials:
Car Paint Material
Car Paint Material - created to simulate car paints the material can be used to simulate a wide range of metallic surfaces that have a clear coat on top of them. It has three layers - Base, which gives the base color and reflectivity of the material, Flakes which allows us to add tiny flakes on top of the base layer and Coat which adds a clear coat layer over the bottom two layers.
- Base Color – controls both the Diffuse and Reflective colors of the base layer.
- Base Reflection – controls how reflective the layer is. Lower values make the layer more diffuse and higher values make it more reflective
- Base Glossiness – controls how blurry the reflections in the Base layer are. Higher values make the reflection more clear and lower values make them blurrier.
- Flake Color – controls the color of the metal flakes. Usually this color is very similar to the Base Color
- Flake Glossiness – controls the glossiness of the metal flakes and works like any other glossiness parameter. It is not recommended to set this above 0.9 as it may produce artifacts.
- Flake Orientation – controls the orientation of the flakes relative to the surface normal. When it is set to 0.0, all flakes are perfectly aligned with the surface. When it is set to 1.0, the flakes are rotated completely randomly with respect to the normal. Usually this parameter should not have values larger than 0.5
- Flake Density – controls the number of flakes for a certain area. Lower values produce less flakes and higher values produce more flakes. Setting this parameter to 0.0 completely removes the flakes
- Flake Scale – controls the scale of the entire flakes texture. Increasing this parameter increases both the size of the individual flakes and the distance between them.
- Flake Size – controls the size of the flakes relative to the distance between them. Higher values produce bigger flakes and lower values produce smaller flakes.
- Flake filtering – controls how V-Ray is going to filter the flakes so that there is no noise in the final image. You can choose between Simple – a fast but less accurate method and Directional – a more accurate method that needs more RAM and is a bit slower.
- · Flake map size – determines the resolution of the Flakes texture. This value should be close to the resolution at which you will render the final result. This map is kept in the memory and can get very big if the Flake map size is set to a very high resolution, especially when the Flake filtering is set to Directional
- Flake seed – a random seed number from which to generate the Flakes texture.
- Mapping Type – Specifies the method for mapping the flakes. Explicit Mapping Channel is used when your geometry has proper UV coordinates. In most cases however you will use Triplanar Projection in Object Space which allows V-Ray to automatically compute the mapping coordinates.
The Coat layer is similar to the Reflection layer of the Generic V-Ray Material but with Fresnel Reflections always enabled. This allows us to quickly add a thin reflective coat over our Baseand Flakes layers:
- Coat Color – controls the color of the coat layer.
- Coat Strength – controls the strength of the coat reflections when the surface is viewed directly from the front.
- Coat Glossiness – Controls the glossiness of the coat reflections.
Blend material – A special material that allows us to combine multiple materials and blend them together using a grayscale value (color or texture).
- Base Material – specifies the material that is used as a base and over which we will add Coat materials
- Add Coat – clicking this button adds a new Coat material to the stack
- Coat – specifies a material to be used as a Coat layer
- Blend – controls how much of the final result is contributed by the corresponding coating material. If the Blend amount is white, the final result is comprised of the coat material only, and other materials below it are blocked. If the Blend is black, a coat material has no effect on the final result. Gray scale values blend between the current Coat material and all the materials bellow it. This parameter can also be controlled by a texture map.
Bump material – allows us to add a bump map to any material we have in the scene - some materials do not have a bump map slot in their settings and this material is the only way to add bump to them. Stacking multiple Bump Materials together can create a more complex surface material by allowing the use of several bump maps together easily
- Base Material – specifies the material to which we are going to add a Bump Map
- Map – specifies the map that is going to be used to generate the bump effect
- Bump Mult – controls the strength of the bump effect
Hair material – a material designed for shading of hair specifically. It has a Diffuse component, two different reflective components and a Transmission (translucent) component. The Diffuse, Primary and Secondary Specular layers contribute to the way the hair looks when illuminated from the front. The secondary reflection layer represents the part of the light that enters the hair strand and is reflected back to the camera, that is why it depends on the transmission color. The Transmission color contributes to the way the hair looks when it is illuminated from behind.
- Overall Color – a multiplier for all color components in the material used to easily change the look of the entire hair material. It doesn’t affect the Transparency color.
- Diffuse Color – specifies the color of the diffuse component of the shader. This is used for materials made out of cloth threads or other non-translucent fibers, as well as for dirty hair. Note that clean hair or fur does not normally have a diffuse component. We can remove the diffuse component by setting the Diffuse Amount parameter to 0.0.
- Diffuse Amount – a multiplier that controls how much the diffuse component affects the final look of the shader.
- Primary Specular – specifies the color of the primary specular component, which corresponds to light that is reflected off the outer surface of hair strands (see the image above).
- Primary Amount – a multiplier that controls how much the primary specular component affects the final look of the shader.
- Primary Glossiness – controls the glossiness for the primary specular component. Values closer to 1.0 make the hair shinier and sleeker. Lower values give it a matted look.
- Lock to Transmission – when enabled (the default), the Secondary Specular color is derived from the Transmission color. Having this option enabled is the physically accurate way of controlling the secondary specular component and the hair color is mostly determined by the Transmission Color component. You can disable it and manually set the Secondary Specularcolor to get more artistic control over the way the hair looks.
- Secondary Specular – specifies the color of the secondary specular component, which corresponds to light that is reflected off the back surface of the hair strands (see the image above). If Lock to Transmission is enabled, this value is ignored and the Secondary Specular color is derived from the Transmission color.
- Secondary Amount – a multiplier that controls how much the secondary specular component affects the final look of the shader. If Lock to Transmission is enabled, this value is ignored and the Secondary Amount is derived from the Transmission Amount.
- Secondary Glossiness – controls the glossiness for the secondary specular component. Values closer to 1.0 make the hair shinier and sleeker. Lower values give it a matted look
- Transmission – specifies the color for the transmission component, which corresponds to light that goes through the hair strands. This value greatly affects the way hair looks whet it is illuminated from behind.
- Transmission Amount – a multiplier that controls how much the transmission component affects the final look of the shader.
- Transmission Glossiness Length – controls the glossiness of the transmission along the hair strand length.
- Transmission Glossiness Width – controls the glossiness for the transmission component across the hair strand width.
2. Advanced Textures
Dirt Map – a V-Ray specific map that is procedurally generated during rendering. It returns one of two colors (occluded or unoccluded) or a blend between the two depending on whether or not there is geometry close to the shaded point. This allows us to simulate effects like dirt gathering in crevices or wear on edges of the geometry. However, the texture is mainly used to create an ambient occlusion pass. The AO pass darkens the image where the objects are close together in a way fake-simulating contact shadows.
- Unoccluded – specifies the color that will be returned by the texture for unoccluded areas. A texture map can be used for this parameter.
- Occluded – specifies the color that will be returned by the texture for occluded areas. A texture map can be used for this parameter.
- Radius – specifies the amount of area (in scene units) where the Dirt effect is produced. A texture can be used to control the radius. The texture intensity is multiplied by the radius to calculate the final radius at a given surface point. If the texture is white at a given surface point, the full radius value is used. If the texture is black, a radius of 0.0 is used.
- Distribution – controls how the dirt effect is distributed in relation to the contact edges. Larger values concentrate the Dirt effect closer to the contact edges. To generate proper Ambient Occlusion this value should be kept at 1.0
- Falloff – controls the speed of the transition between occluded and unoccluded areas. Larger values make the occluded color fade out faster.
- Bias X/Y/Z – These parameters force the dirt effect to those directions. Negative values can be used for inverting the direction of the effect
Curvature - the curvature texture is somewhat similar to the Dirt Map. It allows us to sample a geometry and detect its curvature. The texture will then return dark values for areas that are dents or holes and lighter values for the peaks. We can then use this texture to shade these areas differently by using it to control a Blend Material and blend different shaders. Setting up this texture requires a bit of experimentation because it greatly depends on the scene scale.
Edges texture - returns one color for the faces of a mesh - Background Color and another color for its edges – Edges Color. The texture can be used in a Bump map slot of a material which will smooth out the sharp edges of the geometry. It is important to note that this is only a shading effect and the original geometry will not be smoothed.
TriPlanar - this texture allows us to assign bitmap or other 2d textures to objects that do not have proper UVs. The texture projects (one or more) textures along the local axes of the object.