Further, by utilizing generated (synthetic) data with 3d scanned human models, or generating your own with something like makehuman or daz3D, you should be able to find a way to UV unwrap a distorted sphere. I've had a lot of success with generating synthetic data like this with Blender 3D and training various neural networks (Mask RCNN / Deeplab for example) with various combinations of this synthetic and real datasets.
Further, by utilizing generated (synthetic) data with 3d scanned human models, or generating your own with something like makehuman or daz3D, you should be able to find a way to UV unwrap a distorted sphere. I've had a lot of success with generating synthetic data like this with Blender 3D and training various neural networks (Mask RCNN / Deeplab for example) with various combinations of this synthetic and real datasets.