INTRODUCTION: THINGS AND STUFF
Ask someone what vision is for and you may get an answer about recognizing objects. Few people will tell you that vision is about recognizing materials. Yet materials are just as important as objects are. Our world involves steel and glass, paper and plastic, food and drink, leather and lace, ice and snow, not to mention blood sweat and tears. Nonetheless, if you peruse the scientific literature in human and machine vision, you will also find a great deal of attention paid to the problem of recognizing objects, and very little to the problem of recognizing materials. Why should this be?
Perhaps it is related to the general preference we have for talking about things rather than stuff.
In detectron2, the term “thing” is used for instance-level tasks, and “stuff” is used for semantic segmentation tasks. Both are used in panoptic segmentation.