Quadtree Generating Networks: Efficient Hierarchical Scene Parsing with Sparse Convolutions

Kashyap Chitta, Jose M. Alvarez and Martial Hebert
Conference Paper, IEEE Winter Conference on Applications of Computer Vision (WACV), March, 2020

Download Publication

Copyright notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder.


Semantic segmentation with Convolutional Neural Networks is a memory-intensive task due to the high spatial resolution of feature maps and output predictions. In this paper, we present Quadtree Generating Networks (QGNs), a novel approach able to drastically reduce the memory footprint of modern semantic segmentation networks. The key idea is to use quadtrees to represent the predictions and target segmentation masks instead of dense pixel grids. Our quadtree representation enables hierarchical processing of an input image, with the most computationally demanding layers only being used at regions in the image containing boundaries between classes. In addition, given a trained model, our representation enables flexible inference schemes to trade-off accuracy and computational cost, allowing the network to adapt in constrained situations such as embedded devices. We demonstrate the benefits of our approach on the Cityscapes, SUN-RGBD and ADE20k datasets. On Cityscapes, we obtain an relative 3% mIoU improvement compared to a dilated network with similar memory consumption; and only receive a 3% relative mIoU drop compared to a large dilated network, while reducing memory consumption by over 4×.

author = {Kashyap Chitta and Jose M. Alvarez and Martial Hebert},
title = {Quadtree Generating Networks: Efficient Hierarchical Scene Parsing with Sparse Convolutions},
booktitle = {IEEE Winter Conference on Applications of Computer Vision (WACV)},
year = {2020},
month = {March},
} 2019-09-17T12:30:30-04:00