Seamless texturing: Part 3 of Creating a realistic looking turtle

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Sep 16, 2005

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Intermediate

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Last we will see how important are Bump, Diffuse and Specular maps to make your model look realistic.

BUMP MAP

I used a Blinn shader since it can simulate both matt (thanks to its soft specular highlight) and shiny surface (useful when the tortoise-shell is wet).

In most cases, starting from the Color map we simply get the bump map. But sometimes this is not possible. Why? Look at the example:



Fig. 35



Fig. 36

Remembering that 3D softwares uses black and white colors to determine how light behaves, fig. 35 clearly shows why in this case we can't simply turn the color map in greyscale; if we did that, we would obtain what you can see in fig. 36. This is because the black spot and other black elements are considered as negative and so pushed down. So, to get the right result (fig. 35) you need to draw the bump map, using the color map as reference. Look at the difference:





Fig. 37



Fig. 38



Fig. 39 - a closer view

Fig. 37 shows the bump map used in fig. 36, while fig. 38 shows the correct bump map.

DIFFUSE MAP

With this map we can control the ability of the material to reflect light in all directions. Starting from the color map we can simply obtain the diffuse map by converting it in grayscale and changing the brightness and contrast values in Photoshop:





Fig. 40 - color map



Fig. 41 - grayscale



Fig. 42 - diffuse map

In this case I increased the brightness (otherwise the tortoise-shell would have appeared too dark) and reduced the contrast values (to make the tortoise-shell look not too shiny):



Fig. 43 - Contrast -60



Fig. 44 - Contrast 0

SPECULAR MAP

The Specular Shading attributes control the appearance of specular highlights on a surface. This means that once you have mapped the specular map on the Specular Color, you need to modify the Eccemtricity (Controls the size of shiny highlights on the surface; small values, produce small highlight that simulate shiny surface), the Specular Roll Off (The ability of the surface to reflect its surroundings; use 0.3 to simulate wet surface) and the Reflectivity, too. To create the specular map start from the bump map and increase or decrease the brightness and contrast values to get the effect (shiny or dull) you want. Look at the examples:





Fig. 45 - Bump map



Fig. 46 - Spcular "shiny"



Fig. 47 - Specular "dull"






Fig. 48



Fig. 49

As you can see, fig. 48 (which uses the dull specular map) is less shiny than fig. 49 (which uses the shiny specular map). But, as I said before, you need to adjust some other values, too:





Fig. 50



Fig. 51



Fig. 52




Fig. 53



Fig. 54



Fig. 55

Well, before the final greetings let's see how wolud appear the tortoise-shell whitout all this maps:



Fig. 56 - Only Color map



Fig. 57 - All maps

(Tip: if you want to see the effect using a map or not, hide it during the rendering. To do this left click on the attribute, Diffuse for exsmple, and choose Ignore when Rendering from the pop up menu. To reset, left click and choose Don't Ignore when Rendering):



Fig. 58

The arrow indicates the icon that appears when you choose Ignore when Rendering.

Bye!
Denis Zen

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