Step 5. Run the Polar + Bake + Normal Map pipeline

Time: 5 minutes.

What the pipeline does

The Polar pipeline is the first of two starred recommended workflows in the Mesh menu. It does three things in sequence:

1. Polar warp: maps the Blue Morpho photo onto the Monarch's UV space using polar coordinates centered on the body. The wings get the iridescent pattern; the body stays correct.
2. Bake: writes the warped result as a flat albedo PNG inside your .esk folder at textures/butterfly_albedo.png.
3. Normal map generation: derives a high-frequency normal map from the photo's luminance, writing it to textures/butterfly_normal.png. This gives the wings their characteristic PBR sparkle when lit.

Polar warp is fast (about 3 seconds on an M2; about 5 on a current Intel chip) because the math is closed-form. It also handles non-flat butterfly wings well because the body acts as a stable center.

Make sure the model is selected

Click the Monarch model in the canvas (not the reference photo). It should pick up the accent-color selection outline. The Channel Box should show mesh_kind = butterfly.

If you accidentally select the photo or a landmark, the pipeline will refuse to run with a status bar message: "Polar transfer needs a Mesh3D selection."

Run it

From the menu bar choose Mesh > Transfer Texture > Polar + Bake + Normal Map (PBR). The starred entry sits near the top of the Transfer Texture submenu.

The Designer opens a small progress HUD in the lower-left corner of the canvas:

Polar warp           ████████████████ 100%
Bake to atlas        ████████░░░░░░░░  52%
Generate normal map  ░░░░░░░░░░░░░░░░   0%

When all three bars fill, the HUD disappears and the model in the canvas updates to show the new Blue Morpho-tinted wings.

See the result

In the canvas, the Monarch's wings now carry the Blue Morpho's iridescent pattern. The body stays its original Monarch orange. The abdomen retains its black-and-white stripe.

If you switch to Textured + Lit mode (press 7 or choose View > Textured + Lit), the normal map kicks in and you see the wings catch highlights as you orbit. Orbit by holding Alt + middle mouse and dragging; or use the orbit gizmo in the upper-right corner of the canvas.

Inspect the files on disk

Open the Assets tab in the Project Explorer. The Textures group now shows two new entries inside your .esk folder:

butterfly.esk  · Reveal in Finder
+ Import Asset...
Textures · 3
  textures/butterfly_albedo.png
  textures/butterfly_normal.png
  ../butterfly/iridescentwinged_butterfly.png   ↗ external
3D Models · 1
  _3ds/butterfly.3ds   ↗ external

The two newly baked textures live inside the .esk bundle, which means they will travel with the skin when you export at the end of chapter 7.

Click butterfly.esk · Reveal in Finder to open the folder in your OS file browser if you want to inspect the PNGs directly.

Where the texture path lives

The butterfly placement's texture_path in the Channel Box now points at textures/butterfly_albedo.png (relative to the .esk root). The framework loads the path with the same relative resolution at runtime, so the bake travels with the skin no matter where the .esk ends up.

Checkpoint

You should see:

• The Monarch model wearing Blue Morpho wings in the canvas.
• Two new files in the Assets tab: textures/butterfly_albedo.png and textures/butterfly_normal.png.
• The Channel Box's texture_path pointing at the new albedo.
• In Textured + Lit mode, the wings sparkle as you orbit.

If the wings look wrong (for example, the pattern is rotated 90 degrees or one wing is mirrored), check your landmarks in chapter 4 and re-run the pipeline. The most common cause of a bad Polar bake is two landmarks accidentally swapped.

Continue to chapter 6 >>