Diffeomorphic: Hair Section

Print Statistics: For each selected mesh, print the number of vertices, edges, and faces in the terminal window. This is the same tool as in the Low-Poly Section.
Select Strands By Size: Select strands by the number of vertices.
Select Random Strands: Select a certain fraction of mesh hair strands in edit mode.
Make Hair: Convert the active, hair mesh to particle hair of the other selected, human mesh. To avoid confusion, the meshes are listed right below.

Hair: The hair mesh.
Human: The human mesh.

Update Hair: Change particle hair settings.
Color Hair: Change particle hair color.

Hair Types

There are three types of hair in DAZ Studio:

Sheet Hair: The hair is represented by a mesh with planar sheets.
Polyline Hair: The hair is represented by polylines.
Strand-Based Hair: Strands in DAZ Studio, imported into Blender as thin tubes.

All three types can be imported into Blender as meshes, and then converted to particle hair with the Make Hair tool. More information can be found in the following blog posts:

Strand-based hair
Hair and children
Strand-based hair and geografts
Strand-based hair, for real this time
Hair improvements
More hair changes
Preparing mesh hair

Sheet Hair

The DAZ importer can convert certain types of mesh hair to particles. It only works if the hair solely consists of stripes, whose UV coordinates are arranged in a specific way, usually vertically. Fortunately, most hair meshes in DAZ Studio are made in this way.

The hair mesh consists of many disconnected pieces, which are of two types. The actual hairs are narrow bands with UVs arranged vertically, and a skull with a different type of UV coordinates.

We need to separate the skull from the rest of the mesh. In edit mode, select a skull vertex and hit ctrl-L to select all connected vertices. Then hit P and separate the selection to a new mesh.

There are now two meshes. Hair consists solely of bands with vertical UVs. This is the mesh that we will convert to particle hair.

We renamed the other mesh to Scalp and changed the color to brown to distinguish it from the hair.The color is not important because it will not be visible in renders.

Polyline Hair

Polyline hair consists of connected edges which act as hair guides. Apparently it is not possible for ordinary users to create polyline hair, but it is available from many vendors.

Here is the standard Mohawk polyline hair, in DAZ Studio and imported into Blender. The hair guides consists of edges.

Strand-Based Hair (SBH)

SBH is a recent addition to DAZ Studio 4.12. It is stored in an undocumented binary format in the duf files, and can therefore not be directly imported in Blender with the Daz Importer. However, we can get around that problem with the following trick.

In DAZ Studio, select the SBH and go to Line Tesselation in the Parameters tab. Turn on Preview PR Hairs, and set Render Line Tessellation Sides to 2. Setting it to a larger value than 2 will also work, but it increases export time and the dbz file size without improving anything, so the recommended value of this parameter is 2.

Next export the scene to Blender.

Here is SBH in DAZ Studio, and the tesselated hair imported into Blender.

If we look at an individual hair, it appears to be line mesh, but on closer inspection it is really a flat surface. If Line Tesselation Sides were set to a higher value than two, the imported mesh would have more vertices for each point on the curve.

Print Statistics

This is the same tool as in the Low-Poly Section. It is useful to keep track of the size of mesh hair, so we can reduce the number of strands before converting it to particle hair.

Here we have separated the scalp mesh from the Toulouse hair, and we can see the sizes of both meshes.

Select Strands By Size

This tool groups the mesh strands according to size, and the allows us to select strands of specified sizes. There may be a delay between the press of the button and the appearance of the pop-up dialog, because the hair must be evaluated first.

We can speed up hair creation by deleting hair of specified sizes.

Select Random Strands

Another way to speed up hair creation is to reduce the number of strands of the mesh hair that we started from. This tool makes this easy. With the hair mesh selected, press Select Random Strands. A pop-up dialog appears where you can specify the fraction of strands to keep.

Strands are selected at random in edit mode. Now we can easily delete all selected vertices. This leaves Aiko with hair that is thinner but closely resembles the original hair. We may be able to make up for the missing strands by increasing the number of children in the particle hair.

Make Hair

This is the main tool for converting mesh hair to particle hair. The same tool works for sheet hair, polyline hair, and strand-based hair.

With the human selected and her hair active, press Make Hair. Since it can be difficult to remember which mesh to select first, the hair and human meshes are listed below the button, so we can easily detect if the meshes have been selected in the wrong order. Here we intend to let the hair grow on the scalp mesh, but we could have chosen to grow it directly on the head instead.

The options are arranged in three groups.

Create:

Mesh Hair Strand Type:

Sheet: Use for sheet hair
Line: Use for polyline hair
Tube: Use for tesselated SBH. Can also be used for some sheet hair.

Strand Orientation: How the strands are oriented in UV space.

Top-Down: Vertically with roots at top and tips at the bottom. The default and absolutely most common.
Bottom-Up: Vertically with roots at bottom and tips at the top.
Left-Right: Horizontally with roots to the left and tips to the right.
Right-Left: Horizontally with roots to the right and tips to the left.

Keep Mesh Hair: Keep (reconstruct) mesh hair after making particle hair.
Remove Particle Hair: Remove existing particle systems from this mesh.
Resize Hair: Change the number of hair vertices so all strands have the same number, and hence belong to the same particle system.
Hair Length: The number of hair vertices, if hair is resized.
Resize In Blocks: Change the number of hair vertices to a multiple of ten. This results in a moderate number of particle systems and fairly uniform vertex density.
Sparsity: Ignore some hairs if this number exceeds one.

Material:

Multi Materials: Create different particle systems for each material of the original mesh.
Keep Material: Keep the existing materials. Mainly for polyline and strand-based hair, where hair materials are created when the meshes are imported.
Material To Keep: If we create hair with a single material, choose which of the original materials to keep.
Hair Material Method: Method used to create the hair materials, further described in the page on Material Methods.

Hair BSDF: Node tree with the Hair BSDF node (Cycles only).
Hair Principled: Node tree with the Hair Principled node (Cycles only, Blender 2.8x and later only).
Principled: Node tree with a principled node (Eevee and Cycles).

Hair Colors: The colors of the particle hair.After a slight delay Aiko has particle hair, and the mesh hair can be hidden or deleted.

Settings:

Viewport Children: The number of hair children displayed in the viewport.
Render Children: The number of hair children displayed in renders.
Child Radius (mm): Radius of children around parent.
Strand Shape:

Standard: Standard strand shape.
Fading Roots: Root transparency (standard shape with fading roots).
Root And Tip Shrink:

Root Radius (mm): Strand diameter at the root.
Tip Radius (mm): Strand diameter at the tip.

Here the multi-colored Toulouse hair is converted to particle hair and rendered.

The scalp mesh has several particle systems, one for each hair length and for each material.

The Viewport Children and Render Children parameters correspond to the Display Amount and Render Amount in the Children section, and the Child Radius is the Radius.

The Hair Shape parameter, and the Root and Tip Radii, affect the particle settings as shown in the picture above. The Fading Roots option adds a node group to the hair materials, just before the outputs.

The node group adds transparency to the strand roots.

Polyline Hair

The Make Hair tool can also be used for polyline hair. The workflow is the same, except that the Mesh Hair Strand Type must be set to Line. The tool automatically detects the strand type.

Here is the Mohawk hairdo converted to particle hair.

Strand-Based Hair

The Make Hair tool also works for tesselated SBH. In this case the Strand Type must be set to Tube, which is also done automatically.

Below the tesselated SBM is converted to particles and rendered.

Update Hair

Because the character mesh often has many particle systems, it is quite tedious to edit parameters, because the changes must be repeated for each particle system. The DAZ importer has a tool that makes it possible to make the changes only once.