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About Baker

Baker

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Surface Baking, sometimes call skinning, is the transformation of an object procedural texture, lighting or surface definition into a traditional texture map. Baker adds these possibilities to Carrara.
Using the UV mapping of an object, Baker can extract flat texture maps from any Carrara's shader, giving then the possibility to rework it in other traditional 2D software. You can now start shading an object with any Carrara procedural shader, either 2D (UV mapped shaders) or 3D (solid shaders) and then add details to it in your favorite 2D software.

Baker can also bake lightmaps and normal maps: rendering time can be dramatically lowered by using these technics usually used in real time rendering applications. These maps are also very useful to enhance 3D characters modeled for video games.

To bake an object shader, select first the object in the scene, then choose the menu item Edit->Baking or press Ctrl+F. Note that several objects can be selected at the same time: Baker will generate as many maps as there are selected objects.

3 types of map can be exported. The first one, the Texture Map, transforms one of the shader's channels into a texture map. Look for example at this vase model.

Its shader is made of 3D solid textures, one in the diffuse channel and another in the bump channel. To transform the shader's channels into texture maps, first be sure that the UV mapping of the object is accurate. Baker uses the UV map to transform 3D shaders into 2D texture maps, so if the UV mapping has flaws, like overlapping triangles, these will be visible in the baked map.

Then in the Baking dialog, select the Diffuse and the Bump channels. The background color is used for unassigned pixels (the UV mapping might not cover all the UV space). If the object has several shading domains, 3 options are available: you can choose to export all the domains into 1 map (Merge Shading Domains), to create a different map for every shading domain (Separate Shading Domains), or to export only 1 of the domains by selecting it in the popup menu.

These maps can then be used as traditional texture maps with the vase shader to speed up the rendering of the object.

The second type of map Baker can generate is the Light Map. The light map is created using the current scene lighting and rendering engine. For versions previous to Carrara 7, the rendering engine is limited to raytracing. But Since Carrara 7 version, Baker can capture any kind of rendering. For example, the caustic effects generated with the Global Illumination render can be baked in a texture map.

First image: a 3D scene showing caustics.
Second image: the caustics baked in the ground texture.

The 3rd type of map is the Normal Map. The normals can be computed with or without the bump mapping, and can be determined in global or local space. To read normal maps, Baker includes a special shader named Baker Normal Map. This shader is available in the shading room in the Tools shader category and can read any kind of normal map.
A Normal map can be used to store some geometry complexity from a model and reinstitute it as a bump map to a lower resolution one. This way the final object is much faster to compute during rendering time. Here the first rendering was done with a real geometry, the second with a low polygon version of the object and a normal map that countains the details.

Because Baker Normal Map shader can read any kind of normal map, it can also read ZBrush normal maps. Here is a model imported from ZBrush with and without it's normal map:

To read a ZBrush normal map, select the Mirrored option in the Normal Map shader. This type of map create very realistic bump for still object. To animate an object, this normal map need to be converted into a Relative normal map (using Edit->Baker and choosing the Relative option for the normal map).

Baker is available in demo version here. The demo version is full feature with a baking size limited to 128x128.

Differences between Deeper Normal Map shader and Baker Normal Map shader:

The Deeper Normal Map shader and the Baker Normal Map are similar but Baker's is more powerful. Deeper's shader reads only relative (tangential) maps: it uses the information contained in the map to perturb the existing normal on the object.
Baker Normal Map can reads relative or global normal map. The global one simply replaces the object's normal by the one contained in the texture. The object normal information are completely erased and a new normal extracted from the map is used instead.

Here are a few links where you can find more information on Normal Maps:

About the Normal Map used in Baker:
http://amber.rc.arizona.edu/lw/normalmaps.html
http://www.drone.org/tutorials/normal_maps.html
http://www.pinwire.com/article82.html

About the Normal Map used in Deeper:
http://members.shaw.ca/jimht03/normal.html