Adding Detail to Spaceships with Texture (Part 3)

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The final touch in texturing any object is adding some degree of dirt and a general feel of having been used. Often, this can be achieved simply by adding some fractal noise to the diffuse and specular channels of the object's surfaces. In this lesson, we'll look at doing this and then we will look at using diffuse and bump maps with alpha channels to add more customised and controllable battle damage.


1) Previous Step | Next Step

We will be using mostly Layout for this lesson, so that we can render out our results quickly and easily to see what we've just done.

When creating general grime and roughness to a texture, the diffuse channel is usually the best channel to apply your textures.

Open the surface editor and select the Detail Panel 01 surface, then add a second diffuse texture to the surface.

The new texture should have the following settings (or similar: your choice).

Layer / Texture Opacity 50.0%
Texture Type (LW6 Only) Procedural
Blending Mode (LW6 only) Additive
Procedural Type Fractal Noise
Texture Value 70.0%
Frequencies 3
Contrast 2.0
Small Power 0.5
Scale X=3m, Y=3m, Z=3m
diffuse map settings

Note that we are using a texture opacity of 50%. Changing this value allows us to control the amount that the map alters the diffuse image map that is also applied to the diffuse channel of this surface.

The fractal noise is set to have a high contrast and a fairly large scale, but the texture value is fairly similar to the un-modified setting from the main surfaces panel. This will give us a distinct fractal texture, but it will not be so obvious that it detracts from the more important textures. The effect is subtle, but worth the effort for the additional realism it brings.

I proceeded to add this fractal noise layer to most of the surfaces of the object.

The image above allows you to see the differences between the object with and without the fractal texture by clicking the buttons.

2) Previous Step | Next Step

Now that we've added a little grime to the surfaces, how about some wear and tear?

The first thing I will create is a small scorch mark from a laser hit received by our object.

I'm going to apply this map to Detail Panel 03, so take a screengrab of this polygon as we did in the previous lesson, and prepare it for painting.

The techniques described here are very similar to those described by Joe 'Flashfire' Riddle here, but then, there's only one way to make this effect properly, so similarities are bound to happen. You might want to check his tutorial and adapt some of his techniques for this section, as he goes into a little more detail than I do here.

screengrab prepared

3) Previous Step | Next Step

Next, create a new layer (this will be Layer 2 if you prepared your image in the same way as we did previously).

Select a large brush with a soft edge and paint something like the image opposite in the new, empty layer.

This black smear will act as the diffusion map for our scorch mark.

burn painted

4) Previous Step | Next Step

Create a second new layer then paint something like this in the layer, again, using a large, soft-edged brush.

We will use the white component of this image as a bump map to simulate some rupturing of the surface around the scorch mark.


bump map painted

Use the Smudge tool to break up the edges of this white area a little, so that we will have a more interesting bumped area.

That is all the painting that will be required for this effect.

bump map painted

5) Previous Step | Next Step

We must now create Alpha Channels for these effects, so that we can control which parts of the image are used by Lightwave.

Duplicate the image you are currently working on by right-clicking the title bar of the window and selecting Duplicate from the pop-up menu.

Working with the duplicate image, select the layer with the white area we just painted, then choose Load Selection... from the Select menu.

load selection dialogue

If your white area is in Layer 3, choose 'Layer 3 Transparency' as the active channel.

selection loaded

You should see a selection area appear roughly around the white area of your image.

Now bring up the Save Selection... dialogue from the Select menu.

Choose to save the selection as a New channel in the document you are currently working with. This will create the alpha channel for the white area of the image.

save selection dialogue

If you click on the Channels palette (usually nested in the same palette as the Layers Palette), you will see a new channel called Alpha 1 at the bottom of the palette.

This is our alpha channel, which Lightwave will use as a reference for which parts of our image to apply, and which to ignore.

channels palette

6) Previous Step | Next Step

Return to the Layers Palette and turn OFF the layers containing the grey panel image and the black scorch mark.

Next, Flatten the image by selecting Flatten Image from the Layers menu.

Photoshop will ask you to confirm that you want to discard hidden layers.

Confirm this dialogue and the image will flatten.

layers palette

We can now save this image, but it is important that you save it in a format that fully supports the embedded alpha channel. A format such as Photoshop (.psd) or Targa (.tga) is most appropriate here. Save this image as burnBump.psd (or burnBump.tga... depending on your choice of format).

Following these steps, your image should look like this: with a white area on a black background. (The alpha channel will be an identical image).


7) Previous Step | Next Step

Return to your original burn image (the one that still has all its layers intact) and select the layer that contains the black scorch mark.

As we previously did, load the layer transparency as a selection, so that you have a selection area roughly around the black area of the image.
selection loaded
Now save the selection as a New Channel, in order to create the Alpha 1 alpha channel for the image.
selection saved as alpha

Next, in the Layers Palette, turn OFF the layers that contain the light-grey panel image and the white area for the bump map.

Use the Bucket Fill tool to fill the Background layer with pure white colour, and then Flatten the image. You should be left with a black scorch on a white background.

Save this image as burnDiff.psd (your choice of formats, of course, so long as the format supports the alpha channel.)

We will be applying this image to the Diffuse channel of the panel's surface in Lightwave.



8) Previous Step | Next Step

We will now apply our new images to the object.

In Layout, open the Image Editor and load both burnDiff.psd and burnBump.psd, which we just saved in Photoshop.

Check that in the image decription the Alpha Channel is enabled.

alpha channel enabled

Now open the Surface Editor and add a new layer of Diffuse map to the Detail Panel 03 surface.

map settings

Set the map to use burnDiff.psd as the image, projected through the Y axis with no texture antialiasing or pixel blending, then press the Automatic Sizing button. The alpha channel embedded in the image will automatically be applied to the map.

Click Use Texture and then apply a new level of bump map to the surface. This time, set the image to be burnBump.psd and set the texture amplitude to -2.0. This will recess the area implied by the bump map, rather than raising it.

Rendering out the results of this, we see a new scorch mark applied to the panel's surface, but the other textures applied to the panel (the fractal noise, generic panels etc.) are mostly unaffected, due to the use of the alpha channels for our scorch map images.

scorch mapped sucessfully

So there you have it, a quick and easy method for adding almost any kind of battle damage to your objects.

9) Previous Step | Next Step

Using the alpha map technique of applying a diffuse and bump map with an alpha channel, I added some more general battle damage to the ship, such as this set of gouges...

battle damage

... and these deep scratches.

battle damage

texturing complete

Once again, the limit to the amount of this kind of extra detailing you could add is almost limitless, especially as Lightwave has the ability to add infinite layers of texture to a surface.


© 2000 Kier Darby and Alternate Perspective 3D Ltd.