# Incremental Class Discovery for Semantic Segmentation with RGBD Sensing

## TL;DR

This paper introduces an incremental open-world semantic segmentation method using RGBD data that discovers new object classes over time by building and analyzing dense 3D maps, enabling semi-real-time performance.

## Contribution

A novel approach that incrementally learns new classes in semantic segmentation by leveraging 3D map regions, reducing computational complexity and enabling open-world object discovery.

## Key findings

- Successfully clusters known and unseen object classes.
- Achieves semi-real-time processing at 10.7Hz.
- Outperforms some state-of-the-art supervised methods.

## Abstract

This work addresses the task of open world semantic segmentation using RGBD sensing to discover new semantic classes over time. Although there are many types of objects in the real-word, current semantic segmentation methods make a closed world assumption and are trained only to segment a limited number of object classes. Towards a more open world approach, we propose a novel method that incrementally learns new classes for image segmentation. The proposed system first segments each RGBD frame using both color and geometric information, and then aggregates that information to build a single segmented dense 3D map of the environment. The segmented 3D map representation is a key component of our approach as it is used to discover new object classes by identifying coherent regions in the 3D map that have no semantic label. The use of coherent region in the 3D map as a primitive element, rather than traditional elements such as surfels or voxels, also significantly reduces the computational complexity and memory use of our method. It thus leads to semi-real-time performance at {10.7}Hz when incrementally updating the dense 3D map at every frame. Through experiments on the NYUDv2 dataset, we demonstrate that the proposed method is able to correctly cluster objects of both known and unseen classes. We also show the quantitative comparison with the state-of-the-art supervised methods, the processing time of each step, and the influences of each component.