This time I will first explain a few useful tricks to seamless texture your models and then we will see how to do to make the texture maps look realistic. Since I will refer to examples and tecniques I explained in the other two tutorials, I suggest you to take a look at them).

Well, let¡¯s start.

First, we will see how simple is to draw a seamless texture map for different part connecting in the model (for example arms and legs connecting to the character body) using the convert to File Texture command (see previous tutorial in the texture section). As reference we will use Greg, a simple monster I will use to explain how to draw a scar that runs along one side of the character, from the chest down to the leg.



Fig. 1 Greg, our reference model (click to enlarge)

As you can see in the picture below, the part of the model I have underlined is formed by 3 different parts that are in contact:



Fig. 2

So, what you have to do is to take a snapshot of the right or left side of your model (View > Predefined Bookmarks > Right Side/Left Side) and paste it in a Photoshop new document. Cut the image as explained in the previous tutorial, draw the texture and the scar, of course; when you are done go back in Maya. It¡¯s time to project the texture, but this time yuo will project it onto 3 parts at the same time:



Fig. 3



Fig. 4

Fig. 3 shows the result of the side projection.

Fig. 4 underlines the 3 different parts and the scar running over them (since we projected the texture, we applied it in the same way to the left and the side part of the body and to the interior of each leg as well (A) )

Now, to have complete control over the scar, simply use the convert to File Texture command for each part and modify them as you did in the previous tutorial:



Fig. 5 Body (1)



Fig. 6 leg (3)



Fig. 7 "Connection" (2)

It's time to draw the front texture map for both the body and the "connection". So, as you did for the tortoise-shell, render Greg's front view and use it as reference:



Fig. 8



Fig. 9



Fig. 10

Fig. 8 shows the front texture map with the "new" part of the scar: to clearly see the new part in the "converted texture", draw it in a different color). In this picture the arrows show the "connection zone". As you can see I have drawn the scar in thiszone, too, but I won't use it to adjust the texture map of this part of the body. In fact, for a good result it's better to zoom to the "connection zone" and take a snapshot only of it (fig. 9) (Tip: it's better to draw and convert very large texture maps (2048x2048 or so); this way the final map will be more detailed, sharp and you can zoom very closely to it). Fig. 9 shows the scar coming from the body (A) and the new part (B). Fig. 10 shows the final front texture map we will use for the projection onto the "connection zone". Once you are ready project and convert them:



Fig. 11 Body



Fig. 12 "connection"

Finally, using the previous converted maps, draw a new (for both the body and the "connection zone") texture map with the red and the blu part of the scar:



Fig. 13





Fig. 14

+



Fig. 15

=



Fig. 16

(Tip: when converting to file texture, use values such as 256x256 or 512x 512 or 1024x1024 instead of casual values; this way Maya will calculate the map faster and more accurately).

Fig. 13 shows which part of the texture you have to keep to build the new one. Next, fig. 14 to 16, are shown the 2 maps you got before and the final result you will use as color map for the body shader.

Now you must do the same for the connection zone:





Fig. 17

+



Fig. 18

=




Fig. 19

Applying the 2 new texture maps you will get what you can see below:



Fig. 20



Fig. 21

Fig. 21 underlines the connection zone, and in the picture below you can see a closer view of it:



Fig. 22

In fig. 22 you can see that the scar is not so good; it seems to be blurred. This is because you have to change the Filter value (default value is 1) in the Attribute Editor window of the thexture map:



Fig. 23

Changing this value to 0.1 you'll get the right image:



Fig. 24

Obviously you have to do this for all the other texture maps.

Note: if you use a projection map, change this value in its Attribute Editor, too.

The second tip is very quick and simple, but it's extremely useful when you want no seam between 2 connecting parts. Let's see how.

We will consider the neck connecting to the frontal skin which is attached to the tortoise-shell.

After you created the color, specular and diffuse maps, you have to add the Trasparency map, too. The good thing is that for this map you can use a Ramp and you don't need to convert it and do all the huge work you did for the other texture maps. So, double click on the head shader of your turtle and hit the icon just after Trasparency. In the Create Render Node window hit the Textures tab and choose Ramp:



Fig. 25

In the Attribute Editor delete one of the 3 default colors (simply hit the square on the right) and change the others to black and white (this is because Maya, and all the other 3D softwares, uses this 2 colors in the trasparency channel to show or hide the shader); change the value of the 2 colors untill the border of the turtle head connecting to the neck disappears. To change the color values click on the white or black circles on the right and move them up or down:



Fig. 26

After some attempts the result should be similar to what you see below:



Fig. 27



Fig. 28

Now we will see how to create different texture maps (for the Diffuse, Bump and Specular color) and how they affect the quality of the shader.

The first is the Bump map.

As you probably noticed, every surface in real world (even the smoothest) is irregular. For this reason this map is extremely important and lets you "draw" instead of modelling. See below:



Fig. 29



Fig. 30

As you can see above, using a Bump map you don't need to model complex patterns. These images are very simple, but you use the same "tecnique" to simulate the most complex surfaces (the folds of the skin, the cracks in the walls, ecc¡­). As you surely know, the Bump map looses its effects along the borders of the object (fig. 29), so pay attention whith your camera or use a Displacement map which really modify the object geometry (fig. 30).

(Tip: if you use an Environment texture, such as Env sky, as color map for the Reflected color, Maya will not calculate it correctly if there is a Bump map, too. The result is what you see in the image below:



Fig. 31

As you can see, the arrow indicates how the Reflected color (blu) isn't calculated on the relief. To solve the problem just connect the Out Normal of the bump node to the Normal Camera of the Environment texture. To do this:

Window > General Editors > Connection Editor¡­

Open the Multilister and click the arrows of your shader untill you see the bump2d icon:



Fig. 32

Now, drag the bump2d icon to the Left side of the Connection Editor and the EnvSky icon on the Right side:



Fig. 33

Render the scene and note the difference:



Fig. 34

This and many other interesting tricks can be found in the/art/of/maya, Alias/Wavefront.

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

discuss this topic to forum