This is by far one of the most asked topics on Daz3d: How to reduce render times? Ultimately there is no silver bullet to this question, but there are things you can do that can help, mainly in the form of lighting, decluttering your scene, or, if you have the pockets for it, upgrading your computer. There another issue that you might have and not be able to diagnose properly, a bottleneck. So before we talk about the other ways of how to lower your render time, let tackle that.
What’s a bottleneck?
A bottleneck is a problem with resources that cannot be processed properly. How you fix this can be done in one of two ways. The first and most expensive is to upgrade your rig. If the problem is because you have too little ram, simply get more ram. If the problem is processor two slow, upgrade the processor. Getting a new or another video card can also fix the problem but is usually the more pricier of all the upgrade options, especially now. Once your computer no longer needs to create pagefiles, you will be back to fighting normal render times. The second is to get a tool like Scene Optimizer.
Scene Optimizer is a tool that helps reduce the ram cost of the scene by reducing the texture size of objects in the scene, aiding in making things more manageable with the resources your computer has. Do understand that while it can help if you use too many times one a scene, it might make things look worse.
What is rendering?
Rendering is the act of taking a scene that you have staged and attempt to bring it up to a higher fidelity for consumption. The process of doing this can take a considerable amount of time depending on several factors.
You should note I said scene and not the viewport. That is because the render engine WILL RENDER EVERYTHING THAT IS IN THE SCENE, even things that are not in view of the shot. This brings us to the next part; the clutter. The couch, coffee table, the poor bastard being choke slammed, the person doing the choke slam, etc etc. Everything in the scene will add render time whether or not you can see it from your vantage point of your camera so best to hide it or remove it from the scene altogether
Let’s use this scene that I’m working on as an example. Just bringing this into the Iray preview as it is will lock my computer as it renders everything, making it untenable to work with, especially if I’m trying to jump between Iray and texture to stage and preview shot
Fortunately, one way I can deal with this is to simply declutter the scene. There are two ways of doing this the first is to delete everything you don’t need while isn’t a bad idea can be problematic if you are using the timeline. The second way is to organize everything into containers called a group. If the group is hidden everything in the group will also be hidden, while if you just try to hide the parent only the parent will be hidden, things such as clothes and hair will remain visible.
By putting it in a group and hiding it. Clicking on the eye symbol next to the object in question. It will effectively remove it from the scene as if you deleted it. It hasn’t really but does give you the effect you need to pump out a render. To unhide the object just click on the eye symbol again.
Lighting also plays a very important part. The darker your scene is, the longer it will take to render with more of a chance of artifacts (In reference to rendering, an artifact is a defect in the image) popping up in the final render. How you deal with lighting is a very complex subject that has no one right way to do it especially when you are taking into account mood, atmosphere, and whether or not you want to do post work (taking the rendered image and touching it up in an application like Photoshop) afterward. The brightness of all light is governed by its luminance, the higher the number the brighter the light and is normally what is being referred to when people talk about strength of the light.
Before I begin I highly suggest that if you are truly interested in this topic you look up lighting techniques from both film and photography as a lot of the principles of lighting are taken from the fields.
Now the first thing you need to take into account is whether this will be an indoor or outdoor scene
Outdoor scenes are easier to work with as they require less focus lighting.
Indoor scenes are more likely going to give you the most amount of trouble as you attempt to set even lighting across the whole area of a shot.
HDRI or High Dynamic Range Imaging is a specialized type of image that aids in lighting your scene while providing a backdrop (an image that sits in the background,) or a skydome (a literal dome that covers your scene to provide a skyline). While not always necessary, such as with an indoor scene, it should be the first place you start just to try and get a base sense of what kind of lighting you want. If you require the images themselves try hdrihaven.com which is a free resource.
If you still need to improve your lighting solution, the next thing to set up are the independent lights, while you have many choices. I will mainly direct you to use a spotlight (lighting that allows you to point where the light shines) and point lights( a 360 light that shines from a certain point in space) in a three-point setup.
A three-point lighting setup involves using 3 different lights to control how lighting and shadows fall.
Key light or main light is, as its name suggests, the light the other lights in your scene will work off, usually being the most powerful of the three and set at a 45-degree angle from the camera.
Fill lights sit on the opposite side of the camera from the key light and are usually less powerful than the key light, if not half as powerful. They are usually used to get rid of the shadows cast from the key light on the focus
Finally, the backlight, also known as the rim light or hair light, which is normally used to help bring the character out of a background. It is usually set to the same power as the key light
While this is the most used type of lighting set up, it is not the only one and will not work in all situations, especially if you are going for a certain mood or atmosphere. For example, for the scene below, a 3 point lighting setup and the effect of each light will ruin the context if the scene is supposed to show that the focus is watching tv in the dark. The lighting as it was setup is inappropriate for that.
Emission or ghost lighting
Last but not least is Emission or ghost lighting which has several uses both in and out of lighting of a scene. More often than not, they are used in scenes where there is an obvious light source on a screen like a light bulb or LED. But it can also be used to light a scene and interesting ways by giving out a glow depending on the object it is attached to.
Emission lighting can be done with anything, usually by applying the emission shader to the item in question. When using as a means of accenting a scene like LED on a suit or glowing eyes, there is little cause for problems but when using lighting in its own respect in a scene it can cause more than a few, that’s where ghost lights comes in.
The last thing I want to cover before I wrap this up lighting temperature, which refers to the color of the light. The lower the temperature the redder the light will be while a higher temperature will turn the light blue. In the image above I have it set to 10k giving it a very cool glow like being in front of a tv in the dark.
Special thank you to Envixer for helping out with the section on bottlenecks.