Design input best practices: symmetric and asymmetric coin faces

Design artwork is geometry input

The front and back images do more than decorate the challenge coin faces. Their alpha channels define the solid region used to build the outer contour, holes, side walls, rounded transitions, and the front/back surface regions. A pixel with alpha below 0.5 is treated as empty; alpha at or above 0.5 is treated as solid.

This is why a clean alpha silhouette matters more than a visually complex RGB image. Keep the intended solid area continuous, remove accidental transparent specks, and inspect small openings at 100% zoom. Thin bridges, isolated fragments, and near-touching holes can make the generated topology unnecessarily fragile.

Choose the right relationship between the two faces

The editor supports both symmetric and asymmetric designs. A symmetric design has the same silhouette on both faces. An asymmetric design intentionally uses different silhouettes, such as a large front face paired with a smaller back face, or one face extending beyond the other.

Choose this relationship before you begin Model work. Changing a silhouette later is a geometry change, not a cosmetic adjustment: it requires rebuilding the model and invalidates surface-detail results made for the previous surface layout.

Rule for symmetric designs: match exactly

When the design is meant to be symmetric, the front and back must use exactly the same shape and transform. Match the source contour, canvas position, center point, scale, rotation, crop, and every hole. Do not recreate the opposite face by eye, even when it looks close enough in 2D.

A small mismatch can cause the two surfaces to sample different regions after geometry is generated. The visible results can be subtle but serious: coin-surface details no longer line up as expected, a small border appears on only one face, or a feature that should be continuous across the body becomes uneven.

The reliable workflow is to duplicate the approved face, then change only the visual artwork that does not affect alpha. If the alpha must be edited, apply the same edit to both faces and verify that their solid masks still overlap exactly.

Asymmetric designs are valid, but need an intentional overlay

Different front and back silhouettes are supported. Where one face extends beyond the other, the model contains an overlay transition: the extended face remains part of that face surface, while the generated side wall closes the difference between the two contours. This is a designed geometric condition, not an error to hide with a depth map.

Use asymmetry deliberately. Keep the overlap area broad enough for a clean transition, avoid extremely thin rings or needle-like extensions, and make sure important motifs do not sit across a boundary that will become a side or rounded transition. Plan the edge as part of the composition.

A common valid setup is a large front emblem with a smaller back seal. Another is a one-sided silhouette extension. In both cases, inspect the generated front, back, side, and overlay transition before adding fine coin-surface detail or local materials.

Keep depth maps registered to their own face

The Model page uses the front depth map for the front surface and the back depth map for the back surface. A depth map controls coin-surface height; it cannot repair a wrong silhouette, missing solid region, or poorly planned overlay. Its pixels must remain registered to the design image that produced that face.

For a symmetric design, use depth maps with identical alignment when the surface detail is intended to match. For an asymmetric design, prepare each face independently in its own design bounds. Do not stretch a depth map from the large face to fill a smaller face, and do not expect a front map to shape the back or the side transition.

Know which changes require a rebuild

Changing the outer alpha contour, holes, face position, scale, rotation, crop, or relative overlap changes the generated geometry. Confirm the rebuild before continuing. After the new geometry is ready, review coin-surface detail and material boundaries again because their targets are tied to the generated surface.

Changing only visual color inside an unchanged solid mask does not change the body shape. Coin specifications such as diameter, thickness, and edge settings change the body dimensions but do not by themselves mean that your face artwork has become invalid. Treat these two categories separately: face topology versus body specification.

Practical checklist before Render and Publish

First, verify that at least one face has a continuous solid alpha region. Second, decide whether the design is symmetric or asymmetric. For symmetry, compare both masks at the same size and placement; for asymmetry, rotate the generated model and inspect the overlay and side transition. Third, upload face-specific depth maps and verify coin-surface detail on each intended face.

Only then proceed to Render. Material slots, ID regions, and weights are saved against the constructed model. Rebuilding after detailed material work is possible, but it should be a deliberate revision step followed by a visual review, not an accidental consequence of an unplanned Design edit.