diffuse diffuse reflection refraction diffuse mapping diffuse reflection reflection filter mapping mapping reflection

Transcription

1 Matières 1

2 2

3 3

4 mapping diffuse reflection diffuse transparency reflection refraction diffuse mapping diffuse reflection diffuse reflection filter mapping bump mapping mapping mapping diffuse reflection toon mapping reflection mapping reflection mapping reflection displacement 4

5 the materialization process 5

6 0 the Material Editor 6

7 V-Ray Material Editor 1. Material Preview, the Update Preview button allows you to preview the adjusted materials in real time (=no need for rendering). 2. Material Workplace shows all the materials in the scene. > Right click to add, import, export, rename, pack, remove materials, such as assigning a material to layers or objects, or adding layers (such as reflections, refractions) to the materials. 3. Options for material control. Any necessary changes have to be done in this area tip V-Ray automatically updates the changes of materials to the object, is not necessary to apply materials again. 7

8 How to export > Right click on the material you wish to export > select export option to export this material. N. B. The File extension is.vismat, the file is 1 KB. This file can be imported, packed or sent to other users later on. import > Right click on Scene Material > select Import new material to import a saved material file. pack > Right click on the material you wish to pack and select pack. This feature is very useful, because you can save the textures and a preview of your material in a single file, therefore import it. 8

9 1 assigning a material 9

10 Assigning a material Layer It s possible to apply materials by layers, objects, parents or plugin. For a better organization of the Workspace, it s recommended to apply materials by layer (made exception for those cases in which a singular mapping has to be applied to a particular surface). 1. >open the material editor 2. >right click on a material in the scene s materials list 3. >apply the material to a layer tip select all the objects in the scene and checkout Properties > Material > Assign by Layer 10

11 2 creating a basic material 11

12 Diffuse 12

13 Diffuse Layer When you make a material, it s diffuse by default, which means it only contains one diffuse layer. You can select the color of the diffuse layer by clicking on the color picker or you can use a texture by clicking on the m near the color (we ll see this feature later on). 1. Color - used to select the color of the diffuse layer (base color of the material). 2. m (mapping) - used to select a texture or any other type of procedural mapping. 3. Multiplier (numeric slot) - not in all versions of Vray (you can do it better in Photoshop), used to increase/decrease the brightness of the mapping. 4. Transparency - used to add some grade of transparency to the diffuse layer

14 Transparency The Transparency swatch works on a gray scale. When this color is 100% black (RGB value 0), it s 100% opaque. When it s 100% white (RGB 255), it s 100% transparent. [ i.e. If you want the material to be 50% transparent, change the transparency swatch to be medium gray (RGB value 128).] tip N.B. In Max transparency white is opaque, black is transparent. In Rhino, black is opaque and white is transparent. While in the material editor, when the texture editor is open, notice the Invert button under the preview image. Select this swatch when applying the Transparency map and notice the black and white areas have been inverted. 14

15 Transparency channel Diffuse mapping Transparency mapping 15

16 Toon material 16

17 Toon VrayToon is a basic material producing cartoon-style outlines on objects in the scene. Note that VrayToon is not intended to be a full NPR (non-photorealistic rendering) effect. However, it may be useful in many cases. tip toon can be very useful to reproduce the lines of a painting by properly managing the toon settings 17

18 Toon settings Line color, width, Opacity - determines color, the width of the outlines. Distortion - This will be used to distort the outlines. Also a texture can be use to distort the outlines. This works similar to bump-mapping and will take the gradient of the texture as direction for distortion. Note that high output values may be required for larger distortion. Overlap threshold - this determines when outlines will be created for overlapping parts of one and the same object. Lower values will reduce the internal overlapping lines, while higher values will produce more overlap lines. Don t set this value to pure 1.0 as this will fill curved objects completely. Trace bias - this parameter depends on the scale of your scene, it determines the ray bias when the outlines are traced in reflections/refractions. Do secondary - this will cause the outlines to appear in reflections/refractions as well. Note that this may increase render times. Normal threshold - this determines when lines will be created for parts of the same object with varying surface normals (for example, at the inside edges of a box). A value of 0.0 means that only 90 degrees or larger angles will generate internal lines. Higher values mean that more smooth normals can also generate an edge. Don t set this value to pure 1.0 as this will fill curved objects completely. Do Silhouette Mult - this option enables and disables the Silhouette Multiplier. Silhouette Mult - this value will multiply the silhouette effect. Divide By Distance - when this option is enabled toon lines on objects that are closer to the camera will be thicker. Toon lines will be thinner the farther away the objects are from the camera. Maps There are four parameters that allow the user to control the outlines using various texture maps. Line Color map - a texture map for the outline color. Screen-mapped maps will work best. Maps with World XYZ mapping are also supported, but may not work very well. Line Width map - a multiplier texture for the outline width. Screen-mapped maps will work best. Maps with World XYZ mapping are also supported, but may not work very well. Opacity map - a texture for the outline opacity. Screen-mapped textures work best, although World XYZ mapping is also supported. Distortion map - a texture that will be used to distort the outlines. This works similar to bump-mapping and will take the gradient of the texture as direction for distortion. Note that high output values may be required for larger distortion. Screen-mapped textures work best, although World XYZ mapping is also supported. 18

19 2 creating layers tip start from creating a standard material and go on adding layers to it (avoid Vray materials for now) 19

20 Reflection VS Refraction 20

21 Reflection Refraction lightwave lightwave angle of incidence angle of incidence material thickness angle of reflection angle of refracrion The light wave comes from the light source and makes contact with the front face of the material at a given angle. This is known as the angle of incidence. The light wave then bounces off the material at the exact same angle, known as the angle of reflection. Refraction is the way that that the light wave travels through the material. Because of specific thickness and density, it is refracted in the thickness of the material as bounces off of the substance. The angle of the light coming out of the material isn t the same as the angle of the light entering the material. This difference is measured by the Index of Refraction (IOR). 21

22 Reflection layer 22

23 Reflection Layer creation / settings 23

24 Reflection Map By Default the reflection layer has a fresnel map which varies the amount of reflection based on the viewing angle - this is why the edges of the preview sphere seem to give the material a distortion that we come to expect from a reflective sphere. If that map is removed then the reflection is constant over the whole material. Since the reflection color is set to white this leads to complete reflection on the whole material ( ok for chrome/mirror; see the bunny in the previous slide). 24

25 Fresnel IOR Fresnel IOR (Index Of Reflection) is to control the reflection intensity. The Fresnel reflections are a naturally occurring phenomenon that states that an object becomes more reflective the greater the angle at which it is seen ( i.e. think of how the reflection changes moving around a window ) Each material owns its own Fresnel value High IOR > smaller angle needed > less reflection [ A higher Fresnel IOR means that at a slight angle, you can see reflections. At a lower IOR at the same angle, you might not see the material as reflective.] i.e. #BlackBunny has an IOR of

26 Reflection Glossiness Similarly to the IOR, Glossiness is a parameter in both Reflective and Refractive layers. The difference between the two is that the Reflective Glossiness deals strictly with the amount of reflection dealing with the surface (while the refraction glossiness will have an effect on what happened inside the material, therefore having and effect on the transparency). It s through this parameter that the materials can appear frosted. The refraction will become more blurry as the Refraction Glossiness decreases. The control over the uneven nature of a reflective material can be controlled with this parameter. The amount of reflection glossiness is actually a two-part equation that deals with the Highlight Glossiness number and the Reflection Glossiness number. When these are both set at 1, the material will be mirror like. As these numbers are reduced, the material s reflections become much more blurry ( >see next slide) N.B. Don t reduce these numbers to below 0.5/0.6 >>> HIGHLY increased render times and almost no reflections tip You can increase the glossiness subdivision to improve the quality of the glossiness and remove the noise. This option will increase the rendering time on this material. A good value for the subdivision could be something between ( 32 is recommended) 26

27 Reflection Glossiness + Fresnel IOR Fresnel IOR Reflection Glossiness 27

28 Filter While, by default, the color of the reflection is white, But you can tint the reflection using the reflection Filter. This option allows you to change the color of the reflection producing different metals color. It s extremely useful when you want to achieve a precise chromatic result without changing the lighting parameters of the whole scene. i.e. #CellometalBunny has a yellowish reflection filter, in order to reproduce the effect of the cello in Vermeer s Music Lesson. 28

29 Making Metallic Materials To create a generic metallic material you have to add a reflection layer and to manage the reflection amount using the reflection IOR. (The reflection IOR value is located in the Fresnel effect inside the reflection layer mapping) Basic Chrome Material Recipe: 1. Create a diffuse layer with color/map 2. Add a reflection layer 3. click on the M near the Reflection color. You will see the fresnel effect enable by default. 4. Increase the IOR value 20. tip A metallic reflection has an IOR value between 6 to 26. A plastic reflection has an IOR value between 1 to 5 29

30 Refraction layer 30

31 Fresnel IOR Refraction is the way that that the light wave travels through the material. Because the material has a thickness and a density, the light wave is refracted in the thickness of the material as it bounces off of the substance in the material. The angle of the light coming out of the material isn t the same as the angle of the light entering the material. This difference is measured by the Index of Refraction (IOR). [think of an object bending underwater]. The IOR of air in a vacuum is 1.0 (meaning the angle is the same coming in the material as exiting the material). As the IOR number increases, the more refraction occurs. IOR 1.0 IOR 2.0 tip avoid refraction unless you really have no choice, it significantly slows down rendering time. 31

32 Fog The Fog parameter allows you to give a refractive surface a tint of color. This can be useful when attempting to create a tinted glass, adding a lot of realism because it takes care of smoothing effect of refraction through the thickness of the object in which it is applied. 32

33 Textured 33

34 Textured material To create a textured material, you just have to: 1. create a standard material 2. add a mapping channel to the diffusion layer 3. apply a texbitmap to the mapping 4. upload the.jpg file of the texture you want to use in your scene 34

35 Mapping channel 1. Each object in the scene owns its own mapping channel (you can check it from the object properties). 2. Each mapping channel is identified by a number. 3. A mapping channel holds a set of texture mapping parameters. 4. An object can have any number of channels and therefore can hold any number of texture mapping types. 5. When the textures are applied to an object, the texture is applied using the matching channel number on the object. (If an object has no applied texture mapping, by default a surface mapping is used to map the texture.) tip if you want to transfer all the informations about mapping from an object to another use the MatchMapping tool 35

36 UVW mapping Normally you need to adjust the way in which the map (jpeg image) is applied to the plane on which the material is applied. To do this you need to adjust the UVW map of the plane. N.B. UVW map is a coordinate system that is relative to the object that it s applied to, NOT world coordinates. XYZ coordinates refer to the way in which an object is situated in world space, hence UVW are similar coordinates, but relate to the way the material is applied to the object, having nothing to do with the way that the object is situated in world space The projection literally manages the projection of the texture 2 (imagine this really like a video projector casting an image on an object) UVW Offset determines the position of the texture. 3. UVW Rotation: Adjust the degree of rotation of the Bitmap 4 4. UVW Repeat: Controls how many times a map is repeated within a given space (>therefore, the scale) 36

37 Projection ( Mapping types) The default behavior in Rhino is to treat each surface as a separate object, stretching and orienting the assigned texture to fit. This is almost always wrong. Surface Box Box sides only Surface mapping stretches the texture over the object. Planar mapping projects a 2-D plane onto the side of an object. Box mapping projects a 3-D box onto the sides and top of an object. Box (sides only) mapping sides of an object only, does not cap the mapping to the top and bottom surfaces. Cylindrical Planar Spherical Spherical mapping wraps the object around a sphere. The top edge of the texture shrinks into the top pole and the bottom edge into the bottom pol Cylindrical mapping an image around an object like a cylinder the left and the right edge will join each other. if none of these mapping projections fits on your item, try the Unwrapping or the CustomMapping tools 37

38 Bump 38

39 Bump Maps Visually, a bump is a part of surface owning a slightly different orientation in space than it s neighboring surface. Instead of modeling a bulge in the geometry - which would require a bunch of polygons for each bump, slowing down all related operations - you can reach the same result through the bump layer. Changing the bump and displacement maps will help you add depth and texture to your materials. Bump maps will create the illusion of depth while displacement will actually create a 3D geometry. Displacement maps will take longer to render but will create much better shadows for close up renders. The texture maps are generally black and white, high contrast images that you will add as a separate layer to a given material. 39

40 Bump channel Diffuse mapping Bump mapping 40

41 Displacement 41

42 Displacement map Displacement mapping is a technique for adding detail to your scene geometry without having to model it first. The concept is very similar to bump mapping. However, bump mapping is a shading effect that only changes the appearance of a surface, while displacement mapping actually modifies the surface. You can use your current bump b/w map as displacement maps. In the Maps rollout of the material options there will be an option for Displacement. Enable displacement by clicking the check box on the left, and then proceed to click on the m to add a displacement map. The multiplier determines the final size of the displacement; this will reference the Amount value in the Displacement rollout. N.B. In the V-Ray Options there is a rollout which contains the parameters for displacement. It is important to note that these are global controls for all of the displacement throughout the scene. Currently, there are no individual controls on a per object or material level. This means that you must be aware of the settings within this rollout when adjusting an individual material s displacement. 42

43 displacement parameters Override on : when active, V-Ray will render objects with displacement materials using its own internal micro triangle displacement. When off, the objects displacement will be rendered on a per material basis. Edge length : determines the quality of the displacement. Each triangle of the original mesh is subdivided into a number of subtriangles (more sub-triangles = more detail > slower rendering time >> more RAM usage). View-dependent : a value of 1.0 means that the longest edge of each sub-triangle will be about one pixel long when projected on the screen. When View-dependent is off, Edge length is the maximum sub-triangle edge length in world units. Max. subdivs : controls the maximum sub-triangles generated from any triangle of the original mesh. The value is, in fact, the square root of the maximum number of sub-triangles. (i.e. if Max sub = 100 it means that at most 100 x 100 = sub-triangles will be generated for any given original triangle!) >>> Don t keep this value too high! Amount - this is a scaling parameter for the default displacement. (1.0 = 100%). it is recommended that to leave it constant and that the texture multiplier is used to adjust the displacement of an individual material. Relative to bbox - if on, the actual displacement amount is based on the bounding box of the objects. Tight bounds - when on, V-Ray will try to compute the exact bounding volume of the displaced triangles from the original mesh. This requires pre-sampling of the displacement texture. N.B. : the rendering will be faster if the texture has large black or white areas (no smooth transitions). When it is off, V-Ray will assume worst-case bounding volumes, and will not pre-sample the texture. 43

44 Emissive 44

45 Emissive Layer: The emissive layer allows the material to emit light. These types of material can be used to create effects such as a neon sign, a glowing lamp shade, or a tv/computer screen. These materials will increase render times, possibly to extreme amounts (potentially substantially i.e times). N.B. Do not use these materials as the sole lighting for a scene. It s suggested instead, for best results, to use a light in the scene and only use emissive materials for the glowing that they re meant for. The changes that you make in the Emissive layer will affect the light emitted from the material, not the underlying color itself. The Transparency parameter controls the transparency of the light emitted from the material. tip The physical camera reacts differently to light than a regular camera does. Because of this, you may have to make your light emitting materials significantly brighter. 45

46 Stanford Bunny 46