How do I add fine surface detail like scales, fur or feather lines to a simple modeled shape without sculpting all of it?

The idea

Model the body as a simple smooth form, then lay a thin texture component over it that is made from the reference picture itself. The official component texture tutorial does this with a trout: the body is modeled from vectors, and the picture used as the tracing reference supplies the fine relief that would be tedious to sculpt. The tutorial shows its amounts on screen only, so no heights are quoted here.

Steps

1. Model the base form from your vectors (Create Shape or Two Rail Sweep) and get its overall height right first.
2. Select the reference bitmap. It can be picked in the 2D View or the 3D View.
3. Click Create Component from Bitmap. With a bitmap selected, the software makes a component with the same name as the image. It is scaled automatically and set to Add.
4. Crop it to the body: select the texture component, then the closed outline vector last, and click Clear Component Outside Selected Vectors.
5. Open Smooth Components and take the harshness off. The default is 50%. Keep Preserve Transparency checked.
6. Double-click the texture component and reduce Shape Height until it reads as surface detail on the form and not as a second shape. Keep the combine mode on Add so the detail rides on the body.
7. Keep the texture above the body in the Component Tree.

Know what you are getting

The software reads image brightness as height. Its own grayscale export describes the same mapping: highest areas white, lowest black. So highlights, shadows and color in a photo all become bumps and hollows, whether or not they match the real shape. That is why this works as a shallow texture over a properly modeled form, and why a photo alone rarely makes a good full relief.

Pro tips

• For a true height map file, do not import it as a picture first. Click Create Component from Bitmap with nothing selected and choose the file. The documentation says this avoids reducing the number of shades, which matters most for 16-bit images.
• If dark areas should be high instead of low, switch the texture component's combine mode to Subtract, or invert the picture in Edit Picture before converting.
• Fix single bad spots afterward with the sculpting Smooth tool on that area only.