Content Dev:HD Eyelashes
- Main article: CC Avatar.
Goal
The overall goal for the HD eyelashes is to achieve a natural level of realism with fine details that hold up well in close-up shots.
HD updates to legacy eyelashes
- New eyelashes are composed of individual hair cards.
- The old eyelashes flaps now drive the movement and distribution of the new eyelashes.
- Morphs for the old eyelashes can still be used.
- New eyelashes uses the Hair shader while the old eyelashes still use the legacy PBR material.
- All the hair cards share a single texture map, even for all color variations.
- Visibility for the old eyelashes are lowered to zero, when the new eyelashes are applied.
Eyelash texture fabrication
Fundamentally, the process for creating the Smart Hair material for HD eyelashes is the same as for regular hair: CC 3.4 Hair Creation Process. All individual lash cards of the HD eyelashes should share the same texture map. Care should be taken to flexibly accommodate different eyelash configurations through careful use of texture compartmentalization and buffer space designation.
Texture layout
Eyelash textures created using MetaHuman Groom serve as good examples. Keep in mind that very dense eyelash textures may not be suitable for HD eyelashes.
For optimal results:
- Create 5 rows for eyelash textures, including a buffer area.
- To accommodate different eyelash configurations, keep the bottom row empty for future extensions.
- You can generate the texture row by row and expand it as needed.
Shader settings
- Shader type: Digital_Human Hair
- Required textures channels: Opacity, Flow, Root, and ID
- Texture channels that can be omitted: Base Color, AO and Blend (Depth)
Adjusting the legacy eyelash strips
You should only create and edit the eyelash strips for the neutral base character. To do so, you'll need to load neutral base, then use existing morphs to shape the strip, or export to a 3rd-party 3D software for editing. You can shape the eyelash strips according to your needs, including adjusting the strip length, angle, width, and more to achieve your desired look.
Creation tips
You can use GoZ to adjust the mesh conveniently, as it removes unnecessary associated data such as material settings and texture channels. However, because precise mesh editing in ZBrush can be challenging, you may export the model in OBJ format and edit it in another 3D application such as 3ds Max or Maya. After editing, import the mesh back into ZBrush to replace the eyelash models. This workflow also allows you to continue using GoZ for quick and seamless iteration during the editing process.
- Strive for adequate length of the eyelash strips in order to animate correctly.
- Make sure the size of the lash strips are not smaller than the new strips. (the older set of strips will be slightly larger than the newer versions).
- Ensure that the topology is evenly distributed without distortions.
- Try to keep the original neutral eyelash strip topology intact as much as possible.
- Do not reduce or add to the original topology of the lash strips.
- The attachment of the lash strips to the eyelids must be kept intact (do not reposition the lashes).
- The lash strips are doubled for the upper and lower lashes that should not be spaced too far apart, or staggered.
- When adjusting the lashes, make sure to edit the double strips in conjunction for the lower and upper lashes.
- Some activated CC morphs will cause the doubled lash strips to intersect with one another. Be sure to resolve this problem when it occurs.
Automatic placement must be applied when the eyelash edits are complete. Keep in mind that automatic placement position is different from the default neutral position of the eyelashes.
Generally Correct Position should be used, however there is also the option to use Set Custom Position if you wish to have the eyelash positions based on the current character in the scene. For more detailed explanation, visit: Correcting Eyelash Position (RL Manual).
If needed, you can also restore the original eyelash positions. There are several ways to do this, and all the relevant functions reside under the Correct Eyelashes > Restore Shape menu:
- Restore Default: Restores the eyelashes to its custom shape (In order to restore to the default neutral shape, you'll also need to enable the Default option below).
- Restore from File...: Restores the eyelash mesh based on a geometry file.
New eyelash arrangement
- Make sure the lash card layering has enough thickness so that they don't appear flat.
- Break the symmetry of the eyelashes for the left and right sides. After completion of one side, you can mirror over to the other side and apply mirror adjustments to break the symmetry.
- Make sure the eyelash cards align with the old eyelash strips. Ensure that the length of the lash cards do not exceed the length of the lash strips.
To address the abrupt cut-off look of the eyelash follicles, apply a small gradient on the roots of the eyelash opacity textures.
Right: Sharp roots result in a stark cutoff of the lash follicles.
- Make sure the eyelashes are spaced out evenly without too much sparsity and density in certain areas.
- Pay attention to the area that the eyelashes are growing out of (going by the yellow region in the right-side image of the illustration below).
To ensure the lashes maintain high quality in close-up shots, make sure the mesh has sufficient density to support smooth lash curvature. Avoid any sharp bends in the geometry that may appear unnatural (viewing the model from the side can help you verify this). As a general guideline, each lash card should be divided into six or more segments. The exact number of divisions may vary depending on your production specifications and quality standards.
File submission specifications
Checklist for eyelash files:
- The neutral iAvatar with the adjusted eyelash strips.
- The OBJ file for the eyelash strips separated into upper and lower lashes.
- The CC eyelash element file.
- Textures for the eyelashes (table below).
| Render Filter | Render Image | Padding Image | Compressed Image ×2 | |
|---|---|---|---|---|
| Opacity | Gaussian | TIFF 4K | - | JPG 2K |
| ID | Closet (add padding in PS) | TIFF 4K | TIFF 4K | PNG 2K |
| Root | Closet (add padding in PS) | TIFF 4K | TIFF 4K | JPG 2K |
| Flow (Direction) | Closet (add padding in PS) | TIFF 4K | TIFF 4K | PNG 2K |
| Specular Mask | - | - | - | JPG 2K |
CC5 eyelash creation
Creating eyelash morphs
The following steps are based on the example process for creating the upper eyelashes:
- Import the original eyelash base mesh. Consider baking any applied morphs before proceeding.
- Use the automatic placement function. (The current character model must match the base model used when creating the eyelashes).
- Create the morph slider for “A_Eyelash_Upper.”
- Import the eyelash OBJ file that was created from an external software via Create > Accessory.
- Choose the appropriate eyelash type in the subsequent pop-up menu.
There are 2 formats you can use to save your eyelash assets:
- Eyelash: Saves the entire eyelash as a single asset, including upper and lower lashes. Supports a group of associated morphs.
- Eyelash Element: Used to save the eyelashes as individuals upper and lower parts. Supports a single associated morph slider.
As for facial region assignment, newly create eyelashes will usually be configured properly. However, if you encounter any issues, simply enter the Facial Hair Vertex Assignment mode in the Modify menu to address the problems.
Applying the eyelashes
The character will come with its own shape of eyelashes. Eyelash morphs can be stacked and adjusted strength-wise. You can also mix in the legacy eyelash morphs.
