The Material Editor in Vue dEspirit

June 29, 2007 12:00 am

I first tested Vue dEsprit while trying to reproduce the dirt and stickiness of an oil spill for one of the Renderosity challenges. The Materials Editor in Vue 4 exceeded my expectations so much that I have used Vue ever since.
Rather than summarizing the User Manual dedicated to the Material editor, I will take a pragmatic approach to discussing which aspects of the Vue Materials are key to creating interesting textures. Building Blocks The Material Editor is laid-out in a series of tabs depending on the type of material you are editing. Each of these tabs allows you to edit certain attributes and view the result in a preview window. The Material Editor is based on two building blocks 2D functions and filters. Understand these and you will be creating rich materials in no time. 2D functions define a value between 0 and 1 for a certain position in space. Consider them as a way to create an infinite black and white image. They are represented in the interface by spheres covered with the black and white image generated by the 2D function. Try editing one using the Material Editor. Right click on one of the previews and select Edit Function. Then make sure Procedural values is selected and expand the Type in the Details of layers box. You will find a list of more than 40 procedural functions with exotic names like Noise, Null, or Chipped. These functions can be blended into multiple layers to form complex textures, from repetitive patterns to the aspect of sand or stone. Another alternative is to use a Mapped Layer, which requires you to provide an image. Watch out for the scale of your image and how it is repeated. If you dont want seams to show, you may have to adjust the object. Another often-overlooked aspect of mapped layers is Over-sampling, which smoothes the image when the material is enlarged. The second cornerstone of Vues Material Editor is its system of filters. Filters are a way to control how a certain parameter of the editor will be expressed in your material. For example, if a 2D function has black and white stripes, the default filter will transform black into black, white into white. The inverse filter will inverse the stripes, transforming black into white and white into black. Filters are used to control the expression of colors on a surface or to define the profile of altitudes in a terrain. With these tools in hand, you are now ready to use the Material Editor and the three types of materials available in Vue. Simple Materials Simple materials can be surprisingly complex. They are simple only because they are composed of a single material. The number of options they provide can be intimidating at first, but this material is actually the easiest to edit. The Color tab defines how the material emits colors. Procedural colors are a mix of 2D function, gradient of color and a filter. One end of the gradient corresponds to the value 0 (black) of the function; the other end corresponds to the value 1 (white), with shades of grey in between. The filter is used to modify the behavior of the 2D function. Alternatively, a mapped picture can be the source of colors. This is particularly useful to edit materials of objects that have been mapped in advance, as it is the case of most Poser objects. The Bump tab defines how smooth the surface looks. The 2D function represents bumps (1) and dimples (0). The magnitude of the bump is controlled by the Gain. A Gain of 0 makes the surface flat and a value of 1 creates a strong bump effect. Negative values reverse the effect without having to reverse the 2D function. If an image is used for the Color tab, try applying the same image for the bump map. Improved results can be obtained by editing the bump image to give it a higher contrast or to add noise. The Highlight tab defines how light bounces away from the material. It allows you to make an object look wet, shiny or dull. You can play with the color of highlight to simulate iridescence (try Red highlights on a Blue surface). Since a surface is rarely perfectly smooth, use variable highlights for added realism. The Transparency tab defines how light is allowed to go through your material. This complex tab gives control over special effects such as Fuzziness, Murkiness or Refraction and Caustics. You can use a 2D Function to control how transparency will be distributed across your material, allowing the creation of lace or dirty glass. The Reflection tab defines how the material reflects the environment. Reflectivity can be set to a constant value, defined by a 2D function or by using a Reflection map, if you want to impose a particular reflection in a very complex environment. For example, a multicolored rainbow reflection map can easily create iridescence on the surface of an oily liquid. Finally, the Effects tab defines the global properties of your material, such as brightness and contrast using the Ambient, Diffuse or Luminous values. This tab also allows you to create a glowing halo around your material. Image 2 shows two views of the same object with different values of bump, highlights and reflections.
Mixed Materials Mixed materials are also the key to very complex effects, blending two simple (or mixed) materials into new combinations. It is possible to combine as many materials as you want, although it is rarely necessary to go beyond two or three. The main controls for this material are located on the Material to mix tab. The Mixing proportions slider controls the proportion of each material. The distribution of both sides of a Mixed Material is a combination of a 2D function and a filter. Values of 0 and 1 refer to the materials on the left and right, respectively. The Smoothing Strip allows you to set how smoothly one material turns into the other. The Material Mixing method allows you to control how the materials are blended together. The Simple blend method looks flat and only replaces one material by the other. The Full blend method preserves the bump values of each material, allowing you to fully benefit from the Mixed material. The Cover method is a variation that entirely covers the underlying material. The Influence of environment tab allows you to control the effect of slope, altitude and orientation on the mixed material. For example, use Influence of altitude to create a snow covered terrain or Influence of orientation to add moss on one side of a tree. Image 3 shows an example of mixed material. It also illustrates how important it is to choose the appropriate material scale for the object.
Volumetric Materials The last type of material is defined inside of a volume instead of a surface. This material provides fewer controls than the other two types, but it is also the most difficult to use correctly. This type of material is mostly used for smoke or cloud effects. The Color & Density tab defines the main properties of the material. A bright color and dense setting usually work better. The fuzziness of the material defines how transparent the edges of the material inside the object will be. The Lighting & Effect tab controls how the light interacts with the material. Use a shaded lighting model if you want to give volume and shadows to the material. Unfortunately, volumetric materials are not used a lot in Vue. There remain some problems with transparent parts of a volumetric material, especially when used in a volumetric atmosphere. Also, volumetric materials cannot be mixed. Now What? Once you create and save your material, the last step is to apply it to an object. There is always a list of current materials used in your scene in the Material Summary (under the Display menu or by pressing F6). The Summary of Materials box allows you to edit part of an object or all objects (useful for objects with multiple material groups such as Poser characters). If you are using Vue Pro, the Material browser will allow you to manage your materials more efficiently by displaying mixed materials in a tree structure (enabling direct editing of any sub-material included in a complex material). The Material browser also provides a direct access to all texture maps used by imported objects. Figures 4 and 5 are examples of the flexibility of the Material Editor. Starting from simple geometric shapes, a good mix of scale, bump, color and highlights can dramatically transform a scene.
file_252946.jpg file_252943.jpg
Conclusion Between the sample scenes provided with the software, and the libraries of presets available from e-on, you should have no shortage of useful materials, from rocks and metals to liquids, clouds, woods and special effects. Dont let yourself be intimidated by the apparent complexity of the Material Editor. Just remember to experiment; try different variations of 2D Functions and Filters and soon, your library of Materials will be filled with amazing textures.
file_252945.jpgagiel is not only an amazing artist, but also a member of the Renderosity Team, as Moderator of the Vue dEsprit Forum We invite you to visit agiel's:
January 12, 2007

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