Some textures can work a lot of concepts widely used in the synthesis imaging. The seeing practically introduce some illustrative examples, but we can go making classifications to help us structure this rich variety of possibilities offered.
After add a texture, we adjust the various parameters that govern to fit the object to which we have assigned. This is called “editing process” of textures.
The parameters affecting the textures may relate to various aspects of the same:
- Family textures: The algorithms that generate parametric textures patterns can be grouped into families, and within these new subclassifications are made. For example to produce a grained wood appearance model is used to simulate different marble necessary. Within the family of the woods is not the same cost as the trunk along or perpendicular and of course there is the same vein of a slow-growing tree fast growing one.
- Color Texture: The texture may have two or more colors. A green wood has less red component that we would apply to dry wood. The color of the texture is superimposed or mixed with the material which has the object to obtain the final color. This is one of the most complex rule parameters, due to the wide variety of fusion techniques colors.
- Mode of application: The simplest idea to assimilate the concept of texture is to imagine a skin or “Sticker” we took al object. The texture however is more complex, and can be interpreted as a “mask” that can serve to “add” color, but also to subtract. Really changing the properties of the light on the object surface, may even change how it, “elevating” and “lowering” Texture according to, in what is known as “bump mapping“.
- Additional effects: There are other effects like “type of shadow” cast by an object, flare occurring in water (“Subsurface scatering”) when light passes through different layers and projected onto the bottom…which can be approximated by textures.
- Spatial position: By imagining the texture as a skin is easy to understand that must be positioned with some guidance, stretched or scaled and rotated on the surface. The texture may be repeated, as a brick wall, or adapted to the object (as a ground plane on a sphere). The “mapped” the texture is to establish the manner in which it is “magpie” on the object
Each of these issues deserves careful analysis. Our initial goal is to see globally the usefulness of the textures, leaving the reader to experiment with different types
In the speech that we have been developing wood texture taken as a reference to analyze different control parameters. In this family, you can opt for a model of parallel bands or round (concentric rings)
Will enter the “edit mode” of textures to choose the desired type or family within the possibilities open to us.
By deploying the selection menu the type of textures (Texture type) disponddremos Wood and automatically select a new panel of options for this texture.
Supports two groups: Brands y Rings, representing the two main directions for the grain, extended in the form of anillo.
To give greater realism is often introduce variations to these patterns randomly, avoiding straight lines remaining credibility.
We say that we introduce “noise” creating the pattern of the texture. The more noise, greater complexity in the form that it acquires texture.
Here are some examples of the distortion introduced patronescomo noise about bars and rings of wood texture.
Brands y BrandNoise
Rings y RingNoise
The texture may have two or more colors, exist a menu to define them by color ramps.
Initially texture is a monochromatic range, using the add button add new color ramp gradients are replaced by monochromatic
The preview window will show an approximation of what we get when rendering the texture on the object
Mode of application
We have seen how the texture is applied as if it were a skin. This mode of application is referred “Color Mode”, since the color of texture blends with the color of the material of the object.
To set the application mode select the menu item icon. We defined the texture in the “Mood of texture editing” and had to indicate how we apply it to “material”
To do this we look at the set of windows that are grouped with the window “channels” Texture (Texture). The selected channel in this case is unique, but you can have more channels in the “pile textures”.
How to apply the tab is “Map to”. A set of buttons to add or subtract an effect. Pressing the button once will activate the mode “add”, Press again to change the text color to indicate that the mode is “subtract”. By pressing the mouse off the effect.
Color Mode (Cabbage)
It is interesting to think about the texture like a “mask to apply to the object” with a specific light overlay effect.
When we use the texture to “cover” the object as a skin, use mode “color” (Cabbage).
Each texture can have one or more effects active, and each material can contain multiple textures simultaneously.
Normal Mode (Nor)
Another way out is the way “Normal” (Nor), in which we used to simulate a rough texture of the object, altering the direction of the surface normals.
The shading effect that occurs on the plane of the sample appears on a surface with a series of waves. Modifies visually roughness where applicable.
Fashion Alpha (Alpha)
Alpha channel is what defines the transparency of an image. Textures can change the channel on the object, increasing or decreasing the transparency of the effect.
In-depth study of the translucency or transparency (Contrary to the opacity) and its effects on the synthetic image is beyond the initial goal of this article; later devote a monograph detailing specific and technical possibilities, but we can not textures without highlighting the important role they can play in this regard.
Need to indicate that the object is transparent, for this, in the window that defines the color of the material will reset the alpha channel.
Below we indicate that this effect should be calculated, either by a z-buffer technique in window “Material” or through the window raytracing “Mirror-Transparency” (be specified later what these calculation modes).
Mode “Ray Transp” allow for better outcomes from the graphic point of view, but calculation times can rise substantially, so it is recommended to use “ZTransp” for the first tests so that waiting times are relatively short and quickly observe the effects of the variation of each parameter.
The preview window will reflect our changes immediately, is especially useful in the case of the transparencies.
Our mask therefore present this new look:
If we add a new plane and reconfigure the lighting, observe a new phenomenon. The shadows cast should include the use of transparencies. In the picture below the new object does not receive shadows. The image shows that however if you have reflective properties of the object.
By adding shadows appreciate the relative distance between objects, being helpful for the correct interpretation of the relative positions in space. The shadow cast may correspond to the object that has the texture or the texture itself and transparencies:
When mixed with new semi-transparent objects should be merged correctly. We will see how “raytracing” correctly solve these cases, while the “Z-buffer” curious ambiguities occur which can be used as a dominant effect when.
The application of a fund may further influence on global illumination because it adds light that can be reflected by the mirror surfaces
The use of transparencies to create interesting effects, such as the atmosphere of a planet. It is an interesting exercise in applying textures and transparencies.
To conclude this introduction I leave a few simple examples that motivate the creation of these and other scenes that use these possibilities.
Tutorial made for version 2.49b
- Subsurface scattering (Wikipedia)
- Subsurface scattering Introduction (Blender.org)
- Texture Mapping (Wikipedia)
- Teaching Texture Mapping Visually
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