Manually Placed Borders

Unwrella gives you the option to preserve already existing borders during the unwrapping process. This enables you to use Unwrella for specific workflow requirements like manual texture painting.

When you apply the modifier without checking the ‘Keep Borders’ checkbox Unwrella will discard all existing borders for the UV Set and create its own set of borders to unwrap the model according to the given specification. If you check the box to keep already existing borders Unwrella will adhere the already existing borders to unwrap the mesh.

Please consider that manually placed borders and the specified stretch limit might be incompatible with each other. If the desired stretch limit cannot be maintained with the existing borders, Unwrella will introduce additional borders in order to comply with the limitation. Those additional borders might break the mesh in ways that impact your intended result (i.e. create charts that are impractical for manual painting). In order to resolve this issue you can either introduce additional borders yourself or relax the stretch limitation. With a stretch setting of 1.0 Unwrella will try to use your manual borders exclusively, no matter how extremely it will stretch the charts. New cuts are only used when it’s absolutely impossible for the algorithm to unwrap the mesh at all with the existing borders. With a very low stretch setting Unwrella will usually have to introduce a significant amount of additional borders to comply with the stretch restriction.

Depending on the subsequent processing of the UV map you will have to find a compromise between the stretch limitation and your border placement.

Unwrella will remove a manually placed border if the algorithm considers it to be redundant. This usually happens with borders that don’t separate charts completely but just cut a bit into the surface in areas where it’s not required to spread the surface to maintain stretch requirements (i.e you make a partial cut into a plane). When the two adjacent sides of a border end up lying directly next to each other on the UV map they will be attached to remove the redundant gutter padding between them.