Finishing my series on 3D Surfaces:
I’ve claimed to be “almost done” with this post for a while. It is probably high time to be “actually done” with it. :)
I realized that the discussion in words, while worthwhile, may not be as helpful to some people as actually seeing some images and seeing the effects in action. So, I created a simple scene and did some test renders. In the scene, I have a plane for the floor and another for the back wall. Three cubes on the left and 3 other primitives on the right. A single distant light using raytraced shadows provides the lighting. In each of the images, if you want to see the details of the surface settings, click on the image to see the “media page” as it has a full list of all the relevant channels in the description for each image.
I start with only the Diffuse channel providing any surface values. Specular and Ambient strengths are set to zero.
Diffuse surface color only
Not very interesting, right? No highlitghts, fairly flat colors.
Next, I added some ambient values. Now, in this first set, I did something “odd” on purpose. I set the ambient setting to be opposite of the diffuse setting. For instance, on the Green (0,255,0) cube, I set the ambient color to Magenta (255,0,255). Look what happens, even with Ambient at 100%
100% Colored Ambient Setting
Nothing right? Can’t see a difference between that and the first one? That’s because the Ambient is being multiplied by the diffuse color on a Red, Green, Blue basis. So, since 255 x 0 = 0, you get no effect. This is an extreme case of why you have to think about how your ambient and diffuse colors are going to blend or you may not get the effect you were hoping for! Let’s try again, but this time with a white color for ambient (on the cubes only)…
Cube ambient changed to white @ 100%
Well, at least you can see the effect now. :) But obviously 100% isn’t a good setting. It totally removes all shadow details, etc. Remember back to Part 1 where I said that the Ambient channel was intended to simulate indirect light on the surface? This is basically saying to DAZ Studio / 3Delight “You have a pure white. full strength floodlight shining in all directions!” Not the goal we had in mind, eh? Let’s back that ambient channel down to a more normal fill light level say 30%…
30% White Ambient Surface
A little better. It gives some light effect where the direct light from my distant light isn’t shining, and it doesn’t try to change anything about the colors or anything of my cubes.
You Look Spectacular!
There are two values in the specular channel that really work together to control highlights. The strength channel controls how intense the highlight is, while the glossiness (roughness in some other rendering engines) controls how small or spread out the highlight is across the surface. I started by cranking strength and glossiness to 100%…
100% Specular, 100% Glossiness
What’s that? You don’t see anything? Well, that’s because we told the rendering engine that there is ZERO margin for error on how close the camera has to be to the perfect angle between the light and surface in order to see the highlight. Basically, we made the highlight so small that it’s invisible. Some people will see this effect and think that glossiness is “broken”. It isn’t broken. You just made the surface so smooth that the highlight disappeared. Let’s back it down to 90%…
Well, now we can see something (at least on the curved objects on the right)… but not much. Even 90% is a pretty small highlight. Let’s see what happens at 60%…
Ah. Much better! We can really see that highlight on the objects on the right now. But wait, Karl … you forgot to change the cubes didn’t you?
Nope. I didn’t. The cubes have the same specular settings as the curved objects. You don’t see any highlights because those wide flat surfaces are very consistent about their reflection of light. Since a distant light throws it’s light rays in parallel across the scene, there is no angle where you can see the highlight on the cubes. This illustrates part of the reason why there is no single “right” answer in regards to specular surface settings. If you want to see the cubes “shine”, we need to go even lower on the Glossiness, let’s try 30%…
Yay! The cubes have highlights! Well … if you can call them that. Basically they just look like something went wrong with the surface. And the curved surfaces on the right have a highlight that is so spread out, it is overwhelming the diffuse color. Probably not a setting that is very helpful, hmm?
So, I mentioned that both Specular Strength and Glossiness combine to control how the surface highlights look. In the next series of images, I keep the glossiness setting at 30%, but I vary the strength. I won’t talk about each image, but the captions show the setting that was used…
Glossiness 30%, Specular Strength: 75%
Glossiness 30%, Specular Strength: 50%
Glossiness 30%, Specular Strength: 25%
So, you can see that the spread of the highlight stays the same, but the intensity of the effect goes down (fades). For a final test with the white light, I set Diffuse to 100%, Specular to 25%, Glossiness to 30%, and Ambient to 10%…
Glossiness 30%, Specular Strength: 25%, Ambient 10%
If you compare that to the image at the top, I think you’ll agree that it has much more of an interesting surface look without changing anything at all with the lights.
As I mentioned in previous parts of this series, the settings in your surfaces interact with the setting in your lights. All of the above used a distant light that was White (255,255,255). So the surfaces had a full spectrum of color to reflect. But what happens if I change the light through the secondary colors? In the following series, I change the light color to Magenta (255,0,255), Yellow (255,255,0), and Cyan (0,255,255)…
Notice that as the color of the light removes the Green, Blue, and Red channels, the corresponding cubes turn black, and the curved primitives change to reflect only the part of the spectrum that is included in their surface. Now, you might be wondering “What if I really wanted a cyan light for this image?” Well, you still can, but you need to give the surfaces a little bit of red to render. In the final image, I used a light Cyan (64,255,255) color for the light…
Light Cyan Light
That gives the surface a little bit of Red to reflect to the image, but overall the light still has the cyan quality you might have been looking for.
That’s a Wrap
I think this will do it for my basic surface series. Future tutorials I have in mind include…
- Newbie Mistakes – I’ll show common mistakes that new 3D artists make so they can learn by my bad examples.
- Reflection, Refraction, Transmission, and Transparency – How does light bounce off of and through objects in 3D?
- Point, Spot and Distant Lights – Just the basics on what those lights are and what they can do