Box2Pix: Single-Shot Instance Segmentation by Assigning Pixels to Object Boxes

The task of semantic instance segmentation has gained a large interest within academia as well as industry, especially in the context of autonomous driving. While several published approaches achieve very strong results, only few of them achieve frame rates that are sufficient for the automotive domain. We present an approach that achieves competitive results on the Cityscapes 1 and KITTI 2 datasets, while being twice as fast as any other existing approach. Our method relies on a single fully-convolutional network (FCN 3) predicting object bounding boxes, as well as pixel-wise semantic object classes and an offset vector pointing to corresponding object centers. Using those outputs, we present an efficient and simple post-processing that assigns each object pixel to its best matching object detection, resulting in an instance segmentation obtained at real-time speeds.