Skip to content
SOLO: Segmenting Objects by Locations
Python Cuda C++ Other
Branch: master
Clone or download

SOLO: Segmenting Objects by Locations

This project hosts the code for implementing the SOLO algorithms for instance segmentation.

SOLO: Segmenting Objects by Locations,
Xinlong Wang, Tao Kong, Chunhua Shen, Yuning Jiang, Lei Li
arXiv preprint (arXiv 1912.04488)

SOLOv2: Dynamic, Faster and Stronger,
Xinlong Wang, Rufeng Zhang, Tao Kong, Lei Li, Chunhua Shen
arXiv preprint (arXiv 2003.10152)

More code and models will be released soon. Stay tuned.


  • Totally box-free: SOLO is totally box-free thus not being restricted by (anchor) box locations and scales, and naturally benefits from the inherent advantages of FCNs.
  • Direct instance segmentation: Our method takes an image as input, directly outputs instance masks and corresponding class probabilities, in a fully convolutional, box-free and grouping-free paradigm.
  • State-of-the-art performance: Our best single model based on ResNet-101 and deformable convolutions achieves 41.7% in AP on COCO test-dev (without multi-scale testing). A light-weight version of SOLOv2 executes at 31.3 FPS on a single V100 GPU and yields 37.1% AP.


  • Light-weight models and R101-based models are available. (31/03/2020)
  • SOLOv1 is available. Code and trained models of SOLO and Decoupled SOLO are released. (28/03/2020)


This implementation is based on mmdetection(v1.0.0). Please refer to for installation and dataset preparation.


For your convenience, we provide the following trained models on COCO (more models are coming soon).

Model Multi-scale training Testing time / im AP (minival) Link
SOLO_R50_1x No 77ms 32.9 download
SOLO_R50_3x Yes 77ms 35.8 download
SOLO_R101_3x Yes 86ms 37.1 download
Decoupled_SOLO_R50_1x No 85ms 33.9 download
Decoupled_SOLO_R50_3x Yes 85ms 36.4 download
Decoupled_SOLO_R101_3x Yes 92ms 37.9 download

Light-weight models:

Model Multi-scale training Testing time / im AP (minival) Link
DECOUPLED_SOLO_LIGHT_R50_3x Yes 29ms 33.0 download
DECOUPLED_SOLO_LIGHT_DCN_R50_3x Yes 36ms 35.0 download


A quick demo

Once the installation is done, you can download the provided models and use to run a quick demo.

Train with multiple GPUs

./tools/ ${CONFIG_FILE} ${GPU_NUM}

./tools/ configs/solo/  8

Train with single GPU

python tools/ ${CONFIG_FILE}

python tools/ configs/solo/


python tools/ ${CONFIG_FILE} ${CHECKPOINT_FILE} --show --out  ${OUTPUT_FILE} --eval segm

python tools/ configs/solo/  SOLO_R50_FPN_1x.pth --show --out  results_solo.pkl --eval segm


python tools/ ${CONFIG_FILE} ${CHECKPOINT_FILE} --show --save_dir  ${SAVE_DIR}

python tools/ configs/solo/  SOLO_R50_FPN_1x.pth --show --save_dir  work_dirs/vis_solo

Contributing to the project

Any pull requests or issues are welcome.


Please consider citing our papers in your publications if the project helps your research. BibTeX reference is as follows.

  title={SOLO: Segmenting Objects by Locations},
  author={Wang, Xinlong and Kong, Tao and Shen, Chunhua and Jiang, Yuning and Li, Lei},
  journal={arXiv preprint arXiv:1912.04488},
  title={SOLOv2: Dynamic, Faster and Stronger},
  author={Wang, Xinlong and Zhang, Rufeng and  Kong, Tao and Li, Lei and Shen, Chunhua},
  journal={arXiv preprint arXiv:2003.10152},
You can’t perform that action at this time.