Normal Map Baker

Normal baking is the core trick behind many game-ready low poly assets. The high mesh supplies the fine surface detail, the low mesh supplies the efficient silhouette, and the baker records the difference as a tangent-space normal map. This is different from simply reducing triangles: the high-frequency dents, bevels, cloth folds and sculpted marks are not modeled on the low mesh, but they still affect lighting through the baked texture.

The cage controls whether the bake reads the right part of the high mesh. If the cage sits inside the high mesh, rays miss protrusions and create black gaps; if it is too inflated, rays hit the wrong neighboring surface and create projection smears. For small props, start with a tight cage and a small ray distance, then inspect corners, thin handles and overlapping parts first. Exploded baking, temporarily moving parts apart before baking, helps avoid one piece projecting onto another.

UVs and triangulation decide whether the bake survives export. UV islands must not overlap unless the mirrored result is intentional, and they need padding so mipmaps do not pull pixels from neighbors. Triangulate the low mesh before baking if the engine will triangulate it later; otherwise the diagonal chosen by Unity, Unreal or a GLB exporter can differ from the one used during the bake, creating shading seams. For low poly props, 512 to 1024px normal maps are usually enough; close hero assets can use 2048px.

Normal map orientation must match the engine. OpenGL-style normal maps use one green-channel direction; DirectX-style maps use the opposite. Blender and many glTF workflows expect OpenGL-style Y+, while Unity commonly uses DirectX-style interpretation depending on import settings. If dents look like bumps or lighting seems inverted, flip the green channel before blaming the model. Always test the baked low mesh under the target engine lighting, not only inside the baking tool.