In this tutorial we are going to check out all the new light baking tools in Turtle 4.
The Illuminate Labs Team has been working hard on this new release in order to get you the most advanced lighting techniques available at your fingertips.
We'll check out all the different stuff crammed into Turtle 4, like Radiosity Normal Maps, Polynomial Texture Maps and a lot more.
The tutorial is divided into sections, so you don't have to do it at once. If you already know the basics you should be able to skip ahead to the more fun bits.
Download the Project File here:
Load the the provided scene hangar.mb. This is a pretty detailed scene that we can use to test out the baking tools on.
If you render out a frame, you should get a basic render of the hangar building. This will be the base for the first baking tests.
Baking Tools in Turtle
If you haven't checked out Turtle's baking tools yet, you should know that they are an extensive part of the Turtle toolset. You find the main baking tools, together with the Turtle Renderer, as separate tabs inside the Maya Render Settings when you enable Turtle as the active renderer. There is also a Point Cloud Bake Editor located under Window - Rendering Editors - TURTLE. The baking toolset is divided into four categories:
- Texture Bake - render effects to a surface texture
- Vertex Bake - render out lighting and other data to the vertices of a surface
- Surface Transfer - transfer details from one surface to another
- Point Cloud Bake - transfer lighting and other data to an arbitrary set of points
The huge range of different baking tools aren't there just to confuse you, they all have their specific uses, and they actually complement each other, since specific baking features are only available in specific modes . We will touch on most of the baking tools in some way in this tutorial, but we won't cover all the features in one go. No need in overloading the gray cells too much, right? Check the Turtle Reference Manual for all the greasy details on the different baking tools.
The base of the hangar has been prepared for baking, check out the Display Layers in Maya to see the different components. The hiResBase layer contains all the detailed geometry we'll be baking down to the rough geometry contained in the lowResBase layer. The other parts of the hangar, like the roof and the vents, are contained in the hiResScene layer.
We'll start out by baking a normal map, which we'll make use of later. The Render tab is something like a master control for all the baking tools, so all the different features that were enabled for standard rendering will be enabled for all the baking tools as well.
Find the Final Gather roll-out and switch it off, otherwise we'll get a final gather prepass when we are baking, even though we only want to output normal maps. Now it's time to check out the Surface Transfer tools, so switch the Render Type from Render to Surface Transfer.
Turtle baking tasks are organized into different Bake Layers that can quickly be changed between. You create and organize your baking layers in the Bake Layer editor found under Window - Rendering Editors - TURTLE. We'll only be baking the base of the hangar, so the default layer will do.
Using Surface Transfer is a fairly straightforward process. Imagine that you get a messy Maya scene, with millions of polys or gigantic shading networks. And imagine that you want to sort this out in some way so you can make use of the content for your game or some other application.
All you have to do is sketch out some low-poly proxy geometry that roughly approximates the scene, UV-map it, and you're good to go. The low-res surface goes into the Target Surfaces list, all the detailed nastiness goes into the Source Surfaces list. You won't even have to touch UV-maps or other stuff on the highres geometry, because Turtle will sample the scene from the UV-map specified by your low-res surface!
Open the Display Layer Editor in Maya and make sure the lowResBase layer is visible, all Target Surfaces and Source Surfaces need to be set to visible for the Surface Transfer to succeed. Right-click the lowResBase layer and click Select Objects, choose Add Selected in the Target Surfaces roll-out to prep the low-res geometry for baking. Each Target Surface maintains its own list of Source Surfaces, so make sure the low-res geometry object is selected. Add the objects in the hiResBase layer to the Source Surfaces list by right-clicking the layer in the Display Layer Editor,picking Select Objects, then choosing Add Selected in the Source Surfaces roll-out.
The Outputs should already be set by default to render out only Normals, which is what we want in this case. We have to tweak the Sampling Options, because we have to tune the Surface Transfer to pick up the Source Surfaces that are the farthest away from the Target Surface. Front Sampling and Back Sampling Options controls if sampling is done in the direction of the normals of the Target Surface, or in the opposite direction. We actually want to start sampling a slight distance above the Target Surface, and sample down towards the surface, so we will only use the Back Sampling Mode.
Set both Front Range and Front Bias to 0.0, which will stop sampling in the normal direction. Set the Back Bias to -2.0, which will start sampling from a distance of 2.0 above the surface in the normal direction. Set the Back Range to 3.0; this will make Turtle sample 2.0 units towards the surface, and 1.0 units beyond the surface, so that we pick up any penetrating geometry.
Don't worry too much about the Bias and Range parameters, just remember that the Bias parameters offset the ray origins, the Range parameters control the max distance to Source Surfaces, and Front and Back respectively represent sampling from and towards the surface in respect to the normal.
It is often a good trick to choose either Front or Back Sampling, and set the Range attribute to double the Bias attribute, which will sample the same distance from the surface on either side, but with rays going in a uniform direction.
You should now have Front Range: 0.0, Back Range: 3.0, Front Bias: 0.0 and Back Bias: -2.0. In the Output File roll-out, increase Width and Height to 2048, and hit render.
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