Specular Study

SPECULAR MAP STUDY
A look at Specular Maps and how they are used.

Final pic of a low poly lantern for a presentation given on 6/23/06 at DGXPO.
Specular Maps can add a lot detail and visual information.

Step One: Know your Materials

Just as with any asset involved in Game Industry work, 3D Artists need to be familiar with different material types. When created intelligently, they leave little guesswork as to what the material is. Concrete, wood, plastic, metal, glass, etc., all have different surface types and display wear differently. Specular maps can help more clearly define the condition of the material. Here's a brief look at wood and metal.

Wood

Different woods handle Specular in different ways; therefore knowing about these different types can better define the wood and keep it more true to its nature. For example, knots almost always display a higher sheen because they are typically more dense and hard. Pay particular attention to the light and dark grains of the wood; some dark grains have a sheen and others do not. Let's take a look at one example..

Here is a bedside night stand that I made for a client. It needed to appear worn, roughed-up, and abused. The base texture was made from scratch without photo reference.

Here's the table's Diffuse 'virgin wood' before adding any wear and tear.

Here's the altered top (final Diffuse) with scratches and stains.

The Specular begins the Diffuse material (desaturated) without the distressed layers. My first objective is to adjust the depth I need from light to dark in the wood grain.

Scratches and Dents are then added along with some stains.

Here is the Diffuse and Specular together to demonstrate how the stains were treated. Note that the Diffuse stains were not copied exactly into the Specular. This is because some differences allow a variety of 'action' to show as the light spills across the top. This adds realism and interest to the asset.

Here's an animation of the final asset.

Metal

I have broken out various surface attributes for creating metal materials based on one or more of these six surface types for use in both the Diffuse and the Specular. Subtle additions of one or more can result in some very nice Diffuse and Specular materials. Each are usually applied as either an "Overlay "or "Multiply" in Photoshop (depending on the result I want to get).

Here's a small sample of a larger library for Metal, all tileable of course, accumulated over the years. The library has helped turn projects around quicker than building them from scratch each time.

Just as with wood, some attributes, but not all, from the Diffuse layer can be carried into the new Specular layer. However, new and/or additional patterns of grunge, stains, and smudges can be added to make it appear more 'real' and interesting.

Here is the Diffuse and Specular together. As can be seen, a large amount of new information has been added to the Specular.

Here are animations of the back and front of the sign.

Using Color

Some clients request Color Speculars. These can help make the final asset look better in game. Although challenging at times, they can be fun to create.

Here is an animation moving the light source across the asset.

The Specular color will rarely be the same as the Diffuse color. Experimention with different colors is usually necessary to bring out interesting results.

Here is an animation of the light source moving across the asset.

Note that the brighter the Diffuse materials are like this Human Fighter and the bucket above, there will be some difficulty of recognizing apparent Specular values since it's effect are more subtle.

Let's look at Color Speculars on some darker assets.

As illustrated, using Color Speculars can be very beneficial; especially for brass.

Here is an animation of the light source moving across the asset.

I enjoyed working on this old minecart that needed to be dirty and very rusty.

Here is an animation of the asset.

While most of the Speculaur was medium to dark in color, brighter colors (almost white) was used on the most active worn of edges to help highlight the edges. Let's take a look at adding highlights.

Adding Highlights

To better demonstrate the benefits of highlighting, I created materials based off the cannon model from Game Artist Forum's Speed Texture Competition #40.

This is the low poly model provided by the competition using the Diffuse, Specular, and Normal Map layers I made. To help 'pop' the metal edges defined by the "raised surfaces" of the Normal Map, I added highlights to the Specular along the Normal Map edges. Let's take a closer look...

First, I did my homework and learned more about the cannon type, its origins, and the materials used in its construction. After finding several photos from the era of the French Revolution, I created a pattern and ran with it.

Althouh the metal trim and rivets are relatively dark in the Diffuse, the Specular and Normal Map are used to bring them out. Examining the metal trim on the bottom row will show how white lines were overlayed in the Specular to help emphasize the edges.

To do this, on a new layer, I painted over the Normal Map edges and centered the new white lines on the edges where the Normal Map colors change. The white-lines layer is then moved over to the Specular folder and set to "Overlay". It wasn't quite deep enough, so I then made a duplicate of the white-lines layer, set it to overlayas well, and erased portions of it so as to 'rough-up' the edges and therefore increase the variation along the edges.

Last, I also added highlights to the edges along the cannon barrel. If the opportunity to emphasize edges presents itself, take it. It's well worth the additional time it may take.

I hope this has helped improved your understanding of Specular maps.

Dregs