Archive for 3D Lights

3D Lights – Shapes

I’m going to do a series on the technical bits of lights in 3D software. I plan to cover the following topics…

  • Light Shapes
  • Casting Shadows
  • Light Control and Colors
  • Advanced Topics

This series will be interspersed with other stuff; so no guarantees on the timeframe.

Point Lights

A point light casts light in all directions (like a sphere) from a single point in space. A bare light bulb or the light from a candle is a good real world example. Depending on the software you’re using, point lights may have limited use. For instance in DAZ Studio, the default point light casts a fairly weak light. It doesn’t reach very far at all. And because of the way that shadows work in 3Delight, it doesn’t do well with Deep Shadow Maps either.

Spotlights

Spotlights are kind of like flashlights or theater lights. Like point lights, they emit their light from a single point in 3D space, however unlike point lights, that light has a specific direction. The light spreads from the point of origin along the direction that the light is pointing in a cone shape.

In the basic spotlight for DAZ Studio, we can adjust the spread of that cone, allowing us to control how much of the 3D scene the light affects. In more advanced lights, you may also be able to control things like falloff (how far does the light reach) or apply gels and gobos to the light for special effects.

Spotlights are much more controllable and flexible than point lights. In most scene lighting (especially indoors), Spotlights are going to be your primary source of light.

Distant Lights

Distant lights simulate light cast from a very far source. The Sun and Moon are two such distant light sources which are typically simulated using distant lights. Unlike point and spot lights, distant lights do not have a point of origin in 3D space. The object that you see in the 3D viewport is to help you visualize the angle that the light is pointing. It does not represent where the light “starts”. The control for the distant light could be located underground, but as long as the angle of the light says that it shines on the objects in your scene, it will still light the scene.

In DAZ Studio, distant lights are typically used to simulate the sun, sky or moon. They are also used sometimes by new artists because they are easier to manage, you only have to worry about the angle that it’s shining. However because they light everything in the scene that they can shine on, they are not nearly as flexible as spotlights. Also, because of a limitation of the implementation of Deep Shadow maps, you may have some issues getting shadows to look exactly right using them.

Advanced “Shapes”

There are a couple of other lights that are worth mentioning here before we move on from shapes. These lights are different from the ones I talked about above in technical details of how they interact with the rendering engine, but since they do emit light into your scene, I wanted to mention them.

Area Lights

Technically, an “area light” (aka “mesh light”) isn’t a light in the same way that the others are. Instead an area light is a surface shader which emits light. Using such a shader allows you to make any object in your scene emit light from its surface. These sorts of lights can cast very pleasant consistent light across objects in your scene. In the real world, this is similar to the “umbrellas” and “light boxes” that photographers use. The drawback in 3D rendering is that typically they take longer to render as light rays are emitted from several locations on the object surface.

Ambient / Environment Lights

Ambient (or Environment) lights give the artist greater control over the ambient light in a scene. Most rendering engines have a built in ambient() function which returns a global value for ambient light in the scene. These sorts of lights (for example uberEnvironment which is provided in DAZ Studio) give the artist the ability to control how that light is calculated. They are very useful for simulating the indirect light that bounces around the real world.

Things to Come

My next topic in this series will be on casting shadows as this is typically an area that many artists struggle with getting to look just right.

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Three Lights

Introduction

Many people who are new to the 3D graphics hobby begin by using the built-in features of tools like Poser and DAZ Studio which stop new artists from shooting themselves in the foot when it comes to lighting their scenes. Namely, the tools add one (or more) default lights to a scene so that your image doesn’t turn out a big black nothing. From there they may go on to using pre-built light sets that they get for free or that are included in some sets they buy.

But often I see artists who stop there or who express a bit of trepidation at the idea of adding their own lights to a scene. In this tutorial, I’m going to talk about how to setup a very common lighting rig that photographers use for portrait style photographs. As you might imagine, it also works well for portrait style 3D renders.

The Setup

For the scene, I decided to use Victoria 4.2 from DAZ 3D as my main character. The skin, clothing, and hair all come from Alfaseed and are available at the Runtime DNA online store. Finally the scenery is from a set called Japanese Flair. To be honest, I’m not entirely sure where I got that. I’m using DAZ Studio 4.6 for my rendering tool.

The lights I’m going to be adding are all stock spotlights. I have other lights in my content library that give me more control, but I wanted to show what you can accomplish using the built in lights first. For shadows I used raytraced shadows on all of the spotlights. I don’t care for how DAZ Studio handles deep shadow maps especially when it somes to hair; so I rarely (if ever) use them.

After I got Vicky dressed, I put her on the table in the pose I was looking for, arranged the screen in the background, and framed the shot in the camera. I didn’t want an extreme closeup of her face as I wanted to get some of the details of the Amp’d Lemonade outfit and the IIve skin as well. Then, just to see how things looked, I went ahead and hit the render button.

3 Lights - No Lights

As I mentioned earlier, DAZ Studio helps out the new artist by adding a light at render time if you haven’t explicitly added any so there is some to see. But the light is just a simple light as if it were mounted on top of the camera, not very interesting. Still, this is a good way to render a scene when you’re still working on posing and such since it renders fast as the default light doesn’t have ray tracing or shadows or anything to worry about.

Main Light

The first light I add to the scene is my main light. In this case, I want my main light to light Vicky’s face but also leave some shadows with her hair; so I’m going to put it slightly above and to the left of the camera position. When I’m placing lights, in DAZ Studio, I typically switch my view to the Perspective View, move around until I’m where I want the light to be, then insert the light, telling DS to copy my current position and orientation. The light ends up being located like this…

3 Light Layout - MainThe next thing I do is to make sure the light is pointed where I need it to. Now in a normal scene where my lights are simulating light generated by objects in the scene, I don’t always care where they are pointed. But in this case this rig is being setup to light my portrait subject; so for each light I’m going to target the portion of the subject that the light should be centered on. In the case of the Main light, I point it at Vicky’s head. The screen snips below show how I got there…

3 Light - Point At - MainFor now, I’ll leave the color set to white (255,255,255) and intensity set to full (100%) and render to see the results of adding the main light.

3 Light - Main Only

I think you can quickly see that this is more dramatic than the default “camera light” shown above. However there are clearly some issues. Like the very dark deep shadow behind her back. To alleviate that, we need to add a fill light.

Fill Light

The purpose of the fill light is to provide some light to soften the shadows opposite the main light, but still allow for there to be a contrast between the two sides of the subject. If we were to light them both evenly, the result would look flat an uninteresting. A fill light is typically at a lower angle as well since you want it to fill in some light in the shadows that your higher main light is creating. I’ll drop my fill light below and to the right of my camera like this:

3Light Layout - Fill Light

For now, I leave this light as white at 100% intensity as well. In the case of the fill light, I don’t want it to point up at Vicky’s head, I want the fill light centered lower on that black shadow behind her back; so I’ll have this light point at her hip.

3Light - Point At - Fill

To see the effect of just the fill light, I first turn off the main light and render the fill light itself.

3 Light - Fill Only

Then I turn on the main light to see what they look like together.

3 Light - Main + Fill

Looks over exposed, doesn’t it? It is. The fill light should only be about 20-30% of the strength of the main light, but we’ll address that later. For now, on to the third light in the setup.

Rim Light

The third light is called the rim or key light. This light is placed behind and often above the subject. The purpose of the rim light is to add some highlights that help outline the subject and seperate him/her from the background.

Note: In photography some interesting effects are often done by putting the rim light behind or below the subject. The problem in 3D graphics is that usually 3D hair doesn’t react with the proper translucency to achieve the glowing effect that photographers can get with their cameras.

I’ll place my rim light very high and just slightly behind Vicky like this:

3 Light Layout - Rim LightAgain I leave the color and intensity with the defaults. Then I set the point at target. I could use Vicky’s head again. But techincally what I really want to highlight with this light is her hair; so I target the fantasy drops hair instead.

3 Light - Point At - Rim

I turn off the main and fill lights to check how the rim light is looking…

3 Light - Rim Only

Just shows the highlights (as we’d expect). So I turn on the other 3 lights and render to see them all…

3 Light -Main + Fill + Rim

Well that’s … different … but way too bright time for some tweaking.

Tweaking the Lighting

First thing I need to do is adjust the intensity settings. I typically use 30% for the fill light and 90% for the rim. I could keep the rim at 100% (it isn’t adding THAT much light after all) but I don’t need that much more main lighting than what my Main was already adding. Here’s the effect of just adjusting the intensity levels.

3 Light - All Leveled

Much better! But when I’m lighting a portrait, I typically don’t like the cold harsh white lighting that comes from the default. I prefer to warm up the main light and cool off the fill and rim lights some. I played around with colors a little. Since the hair and skin have some blue and green tones I went a bit cooler on the fill and rim lights than I might normally, but the new settings worked out. I went with the following R,G,B values:

  1. Main : 255, 250, 242
  2. Fill: 240, 245, 255
  3. Rim: 245, 250, 255

The result was this image which I decided to call “good enough” (for me that means “final”):

3 Light - FinalModifications

I’ve had some people ask me before if 3 lights wasn’t too limiting. To which I say not at all! Here are a couple of examples of quick tweaks I did which change the image significantly.

Cool Blue

First by cooling off all of the lights even more, I can take a normal portait style image and make it look noctournal and/or otherwordly.

3 Light - BlueDevil in Disguise

Next I dropped the main light below Vicky. This meant I had to move my fill light closer to the camera. Doing that, I lost some details on the shoulders and hair; so I slid the rim light around so it was behind her head between her shoulders just off the end of the table. This is where those “point at” settings really paid off as I only had to move the lights without having to re-focus them on my subject!

3 Light - Angles

Lighting a subject from below gives them a more sinister look. If you watch old movies, you’ll see that effect used a lot on the villians. I changed nothing at all about Vicky. And yet her smile looks much more mischievious in this image. Also I really like how the fill light casts the shadow on the screen.

Conclusion

I hope that this gives you some understanding of how you can use a fairly simple lighting setup to create portrait style rendered images. Once you get your hands on placing and working with lights yourself I think you’ll find they aren’t nearly as daunting as you may think they are!