UNFOLD3D Generation 6 User Manual

2. Unfolding step by step

Step 1: Import your Model

Unfold3D works on OBJ files: use your usual modeling software (XSI, 3DsMax, Maya...) to create your 3D model, then export it as an OBJ file. A 3D object must respect a certain number of modeling rules to be accepted by Unfold3D: see the Modeling rules section for more details.

Warning: when exporting the mesh from your modeling software, do not use the relative numbering mode, use absolute numbering mode instead.

To load your object in Unfold3D: click the load button, and select your OBJ file. When loading a model, Unfold3D performs a topology validity check on the mesh, which can take a few seconds for big models. This test allows to detect irregularities in the model which can lead to unfolding errors (see Modeling rules for more details).

Step 2: Cut your Model out

Unfold3D will try to unfold your model from an opening line in your model. Before launching the unfold process you need to define this line, by "cutting out" your model (ie: defining seams). Choosing a good cutting line is essential to obtain a good UVs: if your cutting line is too small, you will obtain UVs with a lot surface stretching; if your cut out too many seams, your UVs will be too much disconnected and you will many texture junction problems. Try to place seams in zones of high curvature while keeping the cutting line reasonable small. See the "How to cut?" section for more details on what is a good cut.

Step 3: Unfold!

Now for the easy part: to unfold your model, simply click the Unfold button!

Unfold3D proceeds by iterating an algorithm to optimize a set of constraints, and stops when it has reached a certain satisfaction criterion. During the process, it displays the current UV mapping it tries to optimize. If during the course of the computation the unfolding seems good enough to you, you can press the Stop button to stop the computation manually.

In some cases, if the mesh presents too many irregularities, Unfold3D won't manage to flatten it cleanly. If the computation fails, click the Reinit button to reinitialize the mesh, and try to smooth your model or cut it o3ut some more before retrying to unfold it (see the "How to cut?" section for more details on good mesh conditioning).

Step 4 (optional): Adjust Surface

Once the mesh is unfolded, Unfold3D displays the resulting UV coordinates in the UV window. An unfolded 3D surface always presents some distorsions, some zones where an applied texture will be stretched when mapped on the model. Unfold3D highlights the stretched areas in red: the more intense the color, the higher the stretching. Unfold3D offers a surface adjusting feature to try to reduce the stretching: click the adjust button to apply one step of the surface adjusting algorithm. See the Surface Adjusting section for mored details.

Step 5 (optional): Packing

If the mesh is cut out in several parts, Unfold3D will try to pack them together to optimize the usage of texturing space. You can modify the parameters of the packing step by clicking the Packing Settings button , and fine tune them to obtain an optimal usage of the texture space. See the Packing section for more details.

Step 6: Export the Results

Once computed the UVs, click the Save button to write the UV coordinates in the OBJ file. You can now import Unfold3D's unwrapping back in your usual 3D modeling software for further use.