Creating a Bird and Rendering with Cycles

Creating a Scruffy Bird

FatBird is a scruffy, colorful and clumsy looking creature that’s part bird and part bat. The character is a work in progress and in this post I’ll discuss some of the key points regarding the creation process including modelling, sculpting, UV’s, posing, hair and feathers.

Modelling

As this character will only be used in a still image, the flow of edge loops making up the topology of the model is not too much of a concern. However, it does help to start with a model that resembles the final product (as close as possible) in order to avoid jumping into Edit Mode, which will be slow on dense geometry, and large scale adjustments to the character’s form with the Grab brush in Sculpt Mode as this can potentially result in self-intersecting geometry.

Sculpting

The main brushes used for sculpting were Clay (to add detail), Crease (to create hard edges) and Smooth ( to make the surface appear more organic). The sculpt was also mirrored on the X axis and Enable Dynamic was on for most of the sculpting session.

UV Layout

Once sculpting was finalized, the model was then duplicated and a Decimate modifier was applied to the duplicate. I then tested how much the model’s poly count could be reduced without compromising on the sculpt details. This can be achieved by,

• Adjusting the Decimate Modifier’s settings then Applying the modifier.
• Add a Multires modifier to the decimated model.
• Then add a Shrink Wrap Modifier to the decimated model.
• Target the high res sculpt model from the Shrink Wrap options in the Modifier panel.
• Compare the results of the Decimated model, with Multires and Shrink Wrap to the High Res Sculpt model and repeat the process if necessary, with new settings on the Decimate modifier.

Once a satisfactory result has been achieved, collapse the Low Res model’s modifier stack (either by Applying or Deleting, in order to revert to the original Decimated model). At this stage Edges can then be Marked as Seams on the Low Res model and all subdivided higher levels of the model’s geometry will inherit the Low Res model’s UV Layout via the Multires or Subdivision Surface modifiers.
As most of the bird is covered in fur, adding too much texture detail would be lost in the final render. The most important aspect if this texture as a result is the color.

I subsequently took the baked AO map (above image) into MyPaint to add color, then into the GIMP for further enhancements and finally cloned out the texture’s seams in Blender. The resulting Texture Map follows…

Hair and Feathers

As the final scene that the FatBird is currently being made for will be rendered in Cycles, I decided to use Cycle’s new Strand Renderer to achieve the bird’s scruffy looking plumage and later augment this look with feathers rendered to planes.

In the Particle Settings Panel, I first set the Clump factor to 1. This caused areas of hair throughout the surface of the model to group towards tips. The Shape setting was then used to thin the clumps’ tips even further.

The roughness settings are great for adding variation to the clumps, the above image shows an exaggerated Uniform setting of 7.220.

In order to control where the bird’s hair grows from and how long it is, two Vertex Groups were used. Vertex Groups can easily be created and edited by painting the mesh in Blender’s 3D viewport when in Weight Paint Mode. Once the Vertex Groups are saved they can then be associated with various hair properties in the Particle Settings Panel.

I wanted to keep the feathers in a separate file as I do not intend on using any of the feather’s geometry but instead generating textures from renderings of the feathers.
The feathers consist of an emission object scaled on the Z axis with hair combed on the sides to look like a feather. They are then rendered with an alpha channel, the resulting Texture Map is finally mapped onto a plane in the main scene. This will significantly reduce processing overhead and render times. The feathers have not been added to the final render files yet.

FK and Posing

As the pose rig generated from the Skin Modifier was not able to achieve the results I wanted, a new FK driven pose rig had to be added.

It’s important to note the order of the modifiers in the FatBird’s modifier stack. In particular Shrink Wrap must precede the Armature and the Particle modifier must be at the end.

On a side note, when targeting High Res geometry during rendering, for example by means of a Shrink Wrap modifier. Consider saving the High Res Model in a separate file, then using Link (File Menu > Link) to add the High Res model back to the main scene so that it can be targeted by the Shrink Wrap Modifier. Using this method ensures that your main scene will remain lite and require less RAM.

Context

Finally here’s a sneak peak of the image I’m currently working on that the FatBird character will appear in. In this image we see him posed with fur, but no feathers yet :) If you want to read more about this image here’s an in-depth post on Texturing the character on the right.