Chapter 22
Wood Surfaces
Wood surfaces are one of the surfaces that I am generally quite lazy with. Ordinarily I love painting textures, but wooden surfaces are just a pain because the burls and knots are tricky details to paint. So I always tend to use photographs to create them instead. What’s the point in struggling with painting textures when a photograph is perfectly adequate? And the cool thing about wood is that there are loads of photos available, and, like rusty metal, many are highly suited to being used as textures since they don’t tend to have lighting information in them, especially in the case of finished woods such as wood parquet and other household woods that tend to be smooth.
Most texture CD-ROM collections have hundreds of great high-resolution wood images that you can incorporate into your textures with the greatest of ease. I have a couple of texture collections that contain loads of fantastic wood images that I use all the time while creating wood textures and will be using in these tutorials. Since I cannot redistribute these images, you’ll have to locate wood images of your own, but they are relatively easy to find for free if you are not in a position to purchase a texture collection.
Depending on the type of wood, the shading of the surface can differ rather vastly. Finished woods can be very reflective and smooth, while older wood or untreated wood, such as raw planks, crates, etc., can be very dry and sometimes quite rough.
Wood Tutorial 1: A Guitar
This tutorial covers the very quick and easy process of creating a suitable wood image for a guitar, specifically a detailed Gibson Les Paul guitar model.
We will only be creating a color map for this particular model, since the wood is varnished and totally smooth. For the varnish, I have created an actual layer of polygons surrounding the body of the guitar that we’ll shade as a lacquer to add a great shine to the wood beneath. Doing the lacquer as a separate layer of polygons creates a far better effect than simply trying to create a two-layer effect by shading.
Figure 22-1
1. Open the 7.2-LesPaul.lwo model from the companion CD in Modeler. Go to your Front viewport, zoom into the body part of the guitar, and take a screen shot of it.
2. Open up your paint program and paste the image from your computer’s clipboard into a new document. Crop the image to the size of the model so that the edges of the model’s body touch the edges of the image. This is to ensure that we can use the Automatic Sizing option to fit the texture to the model once it is done.
Figure 22-2
3. Size the image up to at least 1000 pixels in width before continuing. This is to ensure that the texture will look right when viewed up close.
Figure 22-3
4. Find some images of wood that are large enough to be used in a texture. Do a Google image search or look through web sites such as www.imageafter.com to find loads of images that are suitable.
These particular guitars are often made from maple, so I found an image of maple to use. I specifically wanted something with a bit of a pattern in it, since it makes the guitar a little more interesting to look at. If the image you have found is not large enough to cover the guitar body, then clone it around a bit to cover it all. Make sure that you don’t clone any small details too many times, since that can be a dead giveaway that it is fake.
The grain of wood on a guitar runs along the length of it, not across the width. So make sure that any visible grain in your wood image is vertical in your texture.
Figure 22-4
5. If your wood is relatively plain, try to find an image of a wood knot to add to your texture. I found the image shown in Figure 22-5.
6. Mixing a detail like this with the rest of your texture is simple. Start off by desaturating it to gray and place it over the rest of the wood that you have so far to position it where you would like it to be. Don’t place it too near the edge because you’ll be doing some spray painting there in a moment. Erase the edges so that you are simply left with the knot or burl or whatever detail you are adding to the texture. Remember to use a soft-edged eraser so that the edge of the image will blend with the layer below it. See Figure 22-6.
Figure 22-5
7. Now you need to use your eyes. Go to Image>Adjustments>Hue/ Saturation (or whatever the equivalent is in your painting application) and adjust the color and saturation of the image until it blends with the layer beneath it. See Figure 22-7.
Figure 22-6
Figure 22-7
If you have ever worked in compositing or grading, then this type of color and saturation adjustment will be easy for you to do. For the rest of you, just use your best judgment. This is something that you will get better at over time.
Try to get the overall color of the wood to be quite a bright orangey red.
NOTE: I have included this texture on the companion CD in case you couldn’t find any decent wood images. Look for it in the Images folder in the Tutorials directory — it’s called 7.2-LesPaul_wood.tga, a 24-bit Targa file.
8. Now it’s time to add the spray paint work. Take a look at the photograph in Figure 22-8.
This is the type of finish that we are aiming for. The design of the paint along the edges, showing the wood grain in the middle of the body, is called a sunburst — a popular paint finish for guitars.
9. Mix up a nice deep red color using the RGB values 36, 6, 0. Now, carefully following the contours of the screen shot, spray with a soft-edged brush along the edges of the guitar to create the sunburst design. See Figure 22-9.
Figure 22-8
10. Now that we have the paint work and the wood looking fine, it is usually a good idea to darken the texture using a Hue/Saturation Adjustment layer, since wood for guitars is often stained to be darker (it’s just easier to create them initially brighter since we can see the details better). Adjust the texture so that it is darker but still saturated enough. You should ideally end up with a medium to darkish brown that still has a strong hint of red in it. See Figure 22-10.
Figure 22-9
Figure 22-10
11. Open Layout and load the 7.2-LesPaul.lws scene from the companion CD.
Figure 22-11
I have already set up the scene to include an HDR image in Image World for the reflections in the metal and the wood finish.
12. Open the Surface Editor and set up the wood surface first. Select the “wood inner” surface and set up the basic parameters as follows:
Color: 96, 78, 43 (although this doesn’t really matter since we’re applying a texture to it)
Diffuse: 80%
Specularity: 80%
Glossiness: 60%
Reflection: 2%
Leave all the other settings as they are.
13. Open up the Color Texture Editor by clicking the “T” button next to it. Using the default image layer that is created, load the texture that you made. Using Planar as the Projection type, select the z-axis as the Texture Axis and click on the Automatic Sizing option, as shown in Figure 22-13. This should fit your image perfectly onto the model.
Figure 22-12
Figure 22-13
Now to set up the lacquer surface. This will give the body that nice varnished two-layer effect.
14. Select the “lacquer” surface and set up its basic parameters as follows:
Color: 0, 0, 0 (since we want it to be clear)
Diffuse: 10% (a surface should usually have at least a little diffuse applied in order for it to have shadows cast onto it)
Specularity: 80%
Glossiness: 60%
Reflection: 0% (we’ll map it with a gradient in a moment)
Transparency: 95%
Refraction Index: 1.2
Select the Double Sided option.
Leave all the other settings as they are.
15. Go to the Advanced tab and change the Color Highlights value to 80%. This is to prevent the surface from becoming too blown out when lit.
16. Go back to the Basic tab and open the Reflection Texture Editor. Change the default layer to a gradient texture by selecting Gradient from the Layer Type pull-down list at the top right of the panel.
Figure 22-14
17. Change the Input Parameter of the gradient to Incidence Angle. We’ll use this gradient to vary the amount of reflectivity based on the angle at which the surface is viewed.
18. Select the top key that is made on the gradient ramp and change its Value to 30%. We don’t really want the reflections on the lacquer surface to be too strong, so 30% is an adequate amount.
19. Create a new key at the bottom of the gradient ramp and change its Value to 2%. The way the gradient is now, areas that are viewed directly at 90º will appear to be 2% reflective, while areas that are sloping away from our vision increase to a maximum of 30%. However, in this particular instance, a linear increase from 2% to 30% is a little too strong overall, so add a third key to the gradient a little way above the middle.
20. Tweak its Parameter setting to 30.0 and change its Value to 4%.
What this key now does is it keeps the overall reflectivity to a maximum of 4% until shortly before the surface slopes away, at which it rapidly increases to 30% reflectivity.
This isn’t strictly realistic at all, but artistically it creates a more pleasing result for our purposes.
21. Render! Your guitar should look similar to Figure 22-16.
Figure 22-15
This is a decent enough start for the texture. Feel free to go wild by adding fingerprints and smears and whatnot to your reflection map to make it more realistic.
Figure 22-16
Wood Tutorial 2: An Old Crate
This is not a step-by-step tutorial, but rather a guide to creating rougher, more messed up wooden textures using an old wooden crate as an example. Figure 22-17 shows the crate we’ll be looking at. (All three crates in this render are actually the same crate, just cleverly rotated to keep that from being too noticeable.)
Figure 22-17
This scene (and object) is on the companion CD, so feel free to load it up and follow along. The scene is called 7.2_crate.lws and the object is called 7.2_crate.lwo.
I have already set up the UV maps for this crate, exported them from Modeler, and opened the template up in Photoshop.
I start off my texture by scrounging through my vast texture library and finding some appropriate images of planks. I carefully place these planks around on the template, being careful to ensure that no repeated details appear close to one other.
Figure 22-18
You may have noticed that I have left dark lines between each of the planks. This is because dirt and such tends to build up between planks of wood like this, so having these areas darker is not necessarily a problem.
Next up I want to make the paint layer. Since I want this crate to look like it’s had a pretty eventful life, I want to have paint that is chipped away in a lot of places. To do this most effectively, I can use a grunge mapping technique (as discussed in Chapter 11).
Once again, I go through my collection of texture images, looking for some ideal images for this situation. See Figure 22-19 on the following page.
What I do now is desaturate it and increase the contrast, until it looks like Figure 22-20.
Figure 22-19
Figure 22-20
I then clone this around on top of my previously made wood base layer. I also take a white paintbrush and paint very lightly onto some areas to create small patches that don’t have as much gritty detail. See Figure 22-21.
All I have to do now is colorize the layer using Hue/Saturation, which I use to color this layer a fairly bright red, as shown in Figure 22-22.
Figure 22-21
Figure 22-22
I then change the blending mode of the layer to Color Burn and decrease its opacity by 40%, which allows the underlying wood texture to show through the white areas of the texture. This creates a perfect peeled and chipped paint look that actually looks like a thin coating of wood stain.
Figure 22-23
Well, that is the wood part sorted out. You see how easy it is to create details like chipped paint simply from another image of wood? Always remember to think outside the box. Images can be altered to serve many purposes.
All I add now is a little “EXPORT” label to the crate, and use an eraser to eat away at parts of the letters so that they too look old and chipped. See Figure 22-24.
Moving onto the bump map now, I use a very quick and easy method for making the bumps — simply copying the color textures and altering them slightly. I start off by copying the base layer of the color texture and altering its contrast slightly, as well as desaturating it to gray, as shown in Figure 22-25.
Figure 22-24
Figure 22-25
Again, this is another rare situation where it is actually possible to use the desaturated color map as the base for the bump map, since there are no highly contrasted, specific details that will create the wrong effect.
Figure 22-26
I want the paint to appear very slightly raised off the wood, so I copy the paint layer and place it above this bump base layer. Inverting it now makes the paint parts lighter while the other parts appear to go darker. This is the exact effect I need since it will indeed raise the painted parts slightly off the surface.
And that’s all I need for the bump texture. This leaves only the specular texture to be created.
Since this wood is old and dry, it won’t really have much specularity. In fact, the paint will have a very slight specular value while the wood itself will have almost 0%.
I copy my bump textures and reblend them to create the specular map, darkening both considerably. The image in Figure 22-27 shows the specular map; however, please note that this image has been lightened so that you can see more clearly what I have done.
Figure 22-27
And that’s it really. As you have seen, wood textures are definitely one of the simpler types of textures to create because of the way that we can use photographs to create them.
I load up my crates into Layout and render them to get the image that you saw in Figure 22-17.
As I demonstrated in an earlier chapter, I can make the clones of the crate within the scene appear different from one another simply by adding a procedural diffuse map to them, as shown in Figure 22-28.
Figure 22-28
Summary of Tips for Creating Wooden Surfaces
• Finding and using suitable photographs for your textures is usually quicker than painting wooden images.
• Make sure that the direction of the grain in the wood is correct. For example, you wouldn’t have the grain running horizontally across the width of a long plank — the grain would run along the length of it.
• For lacquered, finished wood objects, model an additional layer surrounding the wood and shade it as you would clear plastic.
• For older or dry woods (such as trees, crates, driftwood, or rough planks), use little to no specularity and no glossiness. Using reflection for highlights on dry wood is a waste of rendering time, so stick to specularity in small quantities.
• If you are working on a tree with coarse, chunky bark, use displacement mapping for the bark instead of just a bump map. A bump map will most likely end up looking fake.
• Details such as fingerprints make lacquered wood duller. Add dark streaks from fingerprints to your reflection or specular maps to lessen the effect in those areas.
• When lacquered wood has just been polished, it shows streaks of variations in the reflection map, usually in circular patterns, since this is the pattern in which most people tend to polish. If you really want to be a detail freak, add these patterns to your reflection maps.
• Whatever you do, don’t use that cedarfence.jpg image that every single 3D user on the planet has used at some stage or another as a wood texture. It has been used to death, and it is about time that it is retired from its long-standing run in the 3D world.