train Panoptic Segmentation model on custom dataset

## ❓ How to train Panoptic Segmentation on a custom dataset ?
Hello everyone,

My question is two-fold :
1. What is the expected Detectron2 format for Panoptic Segmentation ? In the PS paper, they are talking about a pixel-wise annotation (either stuff class or instance ID) but it seems that D2 requires bounding boxes as well.
2. Is it possible to train PS on a custom dataset with only pixel-wise annotations ?

Thanks,

Cyril