Tutorial #1 Creating a Specular Map

I’ve wanted to do this for a long time but had not had the chance. Now that I’ve buffed up my skill set and re-educated myself in a lot of things, I thought it’s a great time to share some of what i’ve learned during my toiling.
This tutorial will cover creating and applying a convincing specular map.
Programs used: Photoshop, 3Ds Max (optional),UDK (optional)

What is specularity? The short dirty answer is, specularity is the reflection of an object’s light source or sources on its surface. the nature of object’s surface as well as a few other things will affect how clearly you can see that source being reflected. An orange with it’s rough undulating surface will have a more “scattered” specular highlights(s) vs. an say apple with it’s smooth surface. Hit up Google for more a more detailed in-depth definition if you so desire.

Years ago I was taught that you simply copied the objects diffuse texture, added brightness or contrast in some areas and then called it good. this is incorrect. while using the diffuse as a base is a good start that only get’s you partially there.

You can also do a few other things with a spec map, such as add color, add areas of stains, or smears etc. of course you need to keep in mind what the object is made of and how that affects light reflection. Ok on to the meat of the matter.

This is the object I chose. it’s an aluminum door. a bit tarnished but it has enough variation to give us something nice to play with. I spent some time in Photoshop and created a normals map for the Diffuse texture (this was a bit more involved than just running Xnormals or the NVIDIA filter on the diffuse channel! I’ll post some links and possibly do a tutorial on that at some point)

Notice at the bottom where there is that darker scraped off area. that’s also something to play with. first step is to gather some reference. see how aluminum acts under different lighting situations, ideally from different angles too. that will give you a good idea of how it’s specularity should look. sure you have “some” specular info in the diffuse (color) map we chose but it will help to see said object under different lighting situations.

1. open your color or diffuse map in Photoshop and copy it to a new file. (IMAGE>Duplicate or simply save it with a different file name.)

2. go to IMAGE>Adjustment>Hue/Saturation bring the saturation all the way down to -100. this should convert the image to grey scale. Doing this will give you a better idea of your lights and darks.

3. duplicate your diffuse layer. on this new duplicate layer, go to  SELECT>Color Range. select a light area on your image. what we’re trying to do here is get a selection of all the light values so that we can adjust them on their own. once you have your selection, hit CTRL+I to invert your selection and then hit DELETE. now you should have some light grey values on that layer. adjust the brightness and contrast slightly.
If you want your specular highlights to feel more separated you can go back to your base
layer and make it slightly darker. So far so good.

4. This is where your reference and observation skills come into play even more. look at the reference and your source (in this case the reference for MY subject). notice the little streaks and dark areas on the objects surface. most of what you’re seeing is due to the current lighting. you can push thing’s a bit and add a few more light and dark scratches in different areas, so when the object gets lit and you view it’s surface from different angles you will see a variation in the cuts and grooves and theyre not just limited to what was in the original diffuse texture.
Take a spatter brush and layer on some more lights and darks, like so (image). pay attention to your diffuse map. The take a smaller brush zoom way into your image and start drawing some small streaks, both in black and white. these will give the impression of surface scratches and will sell your specular even more. don’t over do it! And you can also use a scratches brush for this, tons to be found online. once you’re done that’s it!

5. taking it further – around the keyhole and handle usually gets a LOT of hand traffic so you could add a lot of slightly dark spots around those areas to represent smudges from fingers, or scratches to to represent key scratches. You could even tell more of a story and add boot prints or palm prints on the door, all I nthe specular.  these would only be visible dependding on the viewing angle and would add to the viewing experience.

Tune in next time when i’ll walk you thru setting up a material for this in the UDK.

Domo Out!