Tag Archives: ICCV

Self-Supervised Learning Advances Medical Image Classification

In recent years, there has been increasing interest in applying deep learning to medical imaging tasks, with exciting progress in various applications like radiology, pathology and dermatology. Despite the interest, it remains challenging to develop medical imaging models, because high-quality labeled data is often scarce due to the time-consuming effort needed to annotate medical images. Given this, transfer learning is a popular paradigm for building medical imaging models. With this approach, a model is first pre-trained using supervised learning on a large labeled dataset (like ImageNet) and then the learned generic representation is fine-tuned on in-domain medical data.

Other more recent approaches that have proven successful in natural image recognition tasks, especially when labeled examples are scarce, use self-supervised contrastive pre-training, followed by supervised fine-tuning (e.g., SimCLR and MoCo). In pre-training with contrastive learning, generic representations are learned by simultaneously maximizing agreement between differently transformed views of the same image and minimizing agreement between transformed views of different images. Despite their successes, these contrastive learning methods have received limited attention in medical image analysis and their efficacy is yet to be explored.

In “Big Self-Supervised Models Advance Medical Image Classification”, to appear at the International Conference on Computer Vision (ICCV 2021), we study the effectiveness of self-supervised contrastive learning as a pre-training strategy within the domain of medical image classification. We also propose Multi-Instance Contrastive Learning (MICLe), a novel approach that generalizes contrastive learning to leverage special characteristics of medical image datasets. We conduct experiments on two distinct medical image classification tasks: dermatology condition classification from digital camera images (27 categories) and multilabel chest X-ray classification (5 categories). We observe that self-supervised learning on ImageNet, followed by additional self-supervised learning on unlabeled domain-specific medical images, significantly improves the accuracy of medical image classifiers. Specifically, we demonstrate that self-supervised pre-training outperforms supervised pre-training, even when the full ImageNet dataset (14M images and 21.8K classes) is used for supervised pre-training.

SimCLR and Multi Instance Contrastive Learning (MICLe)
Our approach consists of three steps: (1) self-supervised pre-training on unlabeled natural images (using SimCLR); (2) further self-supervised pre-training using unlabeled medical data (using either SimCLR or MICLe); followed by (3) task-specific supervised fine-tuning using labeled medical data.

Our approach comprises three steps: (1) Self-supervised pre-training on unlabeled ImageNet using SimCLR (2) Additional self-supervised pre-training using unlabeled medical images. If multiple images of each medical condition are available, a novel Multi-Instance Contrastive Learning (MICLe) strategy is used to construct more informative positive pairs based on different images. (3) Supervised fine-tuning on labeled medical images. Note that unlike step (1), steps (2) and (3) are task and dataset specific.

After the initial pre-training with SimCLR on unlabeled natural images is complete, we train the model to capture the special characteristics of medical image datasets. This, too, can be done with SimCLR, but this method constructs positive pairs only through augmentation and does not readily leverage patients' meta data for positive pair construction. Alternatively, we use MICLe, which uses multiple images of the underlying pathology for each patient case, when available, to construct more informative positive pairs for self-supervised learning. Such multi-instance data is often available in medical imaging datasets — e.g., frontal and lateral views of mammograms, retinal fundus images from each eye, etc.

Given multiple images of a given patient case, MICLe constructs a positive pair for self-supervised contrastive learning by drawing two crops from two distinct images from the same patient case. Such images may be taken from different viewing angles and show different body parts with the same underlying pathology. This presents a great opportunity for self-supervised learning algorithms to learn representations that are robust to changes of viewpoint, imaging conditions, and other confounding factors in a direct way. MICLe does not require class label information and only relies on different images of an underlying pathology, the type of which may be unknown.

MICLe generalizes contrastive learning to leverage special characteristics of medical image datasets (patient metadata) to create realistic augmentations, yielding further performance boost of image classifiers.

Combining these self-supervised learning strategies, we show that even in a highly competitive production setting we can achieve a sizable gain of 6.7% in top-1 accuracy on dermatology skin condition classification and an improvement of 1.1% in mean AUC on chest X-ray classification, outperforming strong supervised baselines pre-trained on ImageNet (the prevailing protocol for training medical image analysis models). In addition, we show that self-supervised models are robust to distribution shift and can learn efficiently with only a small number of labeled medical images.

Comparison of Supervised and Self-Supervised Pre-training
Despite its simplicity, we observe that pre-training with MICLe consistently improves the performance of dermatology classification over the original method of pre-training with SimCLR under different pre-training dataset and base network architecture choices. Using MICLe for pre-training, translates to (1.18 ± 0.09)% increase in top-1 accuracy for dermatology classification over using SimCLR. The results demonstrate the benefit accrued from utilizing additional metadata or domain knowledge to construct more semantically meaningful augmentations for contrastive pre-training. In addition, our results suggest that wider and deeper models yield greater performance gains, with ResNet-152 (2x width) models often outperforming ResNet-50 (1x width) models or smaller counterparts.

Comparison of supervised and self-supervised pre-training, followed by supervised fine-tuning using two architectures on dermatology and chest X-ray classification. Self-supervised learning utilizes unlabeled domain-specific medical images and significantly outperforms supervised ImageNet pre-training.

Improved Generalization with Self-Supervised Models
For each task we perform pretraining and fine-tuning using the in-domain unlabeled and labeled data respectively. We also use another dataset obtained in a different clinical setting as a shifted dataset to further evaluate the robustness of our method to out-of-domain data. For the chest X-ray task, we note that self-supervised pre-training with either ImageNet or CheXpert data improves generalization, but stacking them both yields further gains. As expected, we also note that when only using ImageNet for self-supervised pre-training, the model performs worse compared to using only in-domain data for pre-training.

To test the performance under distribution shift, for each task, we held out additional labeled datasets for testing that were collected under different clinical settings. We find that the performance improvement in the distribution-shifted dataset (ChestX-ray14) by using self-supervised pre-training (both using ImageNet and CheXpert data) is more pronounced than the original improvement on the CheXpert dataset. This is a valuable finding, as generalization under distribution shift is of paramount importance to clinical applications. On the dermatology task, we observe similar trends for a separate shifted dataset that was collected in skin cancer clinics and had a higher prevalence of malignant conditions. This demonstrates that the robustness of the self-supervised representations to distribution shifts is consistent across tasks.

Evaluation of models on distribution-shifted datasets for the chest-xray interpretation task. We use the model trained on in-domain data to make predictions on an additional shifted dataset without any further fine-tuning (zero-shot transfer learning). We observe that self-supervised pre-training leads to better representations that are more robust to distribution shifts.
Evaluation of models on distribution-shifted datasets for the dermatology task. Our results generally suggest that self-supervised pre-trained models can generalize better to distribution shifts with MICLe pre-training leading to the most gains.

Improved Label Efficiency
We further investigate the label-efficiency of the self-supervised models for medical image classification by fine-tuning the models on different fractions of labeled training data. We use label fractions ranging from 10% to 90% for both Derm and CheXpert training datasets and examine how the performance varies using the different available label fractions for the dermatology task. First, we observe that pre-training using self-supervised models can compensate for low label efficiency for medical image classification, and across the sampled label fractions, self-supervised models consistently outperform the supervised baseline. These results also suggest that MICLe yields proportionally higher gains when fine-tuning with fewer labeled examples. In fact, MICLe is able to match baselines using only 20% of the training data for ResNet-50 (4x) and 30% of the training data for ResNet152 (2x).

Top-1 accuracy for dermatology condition classification for MICLe, SimCLR, and supervised models under different unlabeled pre-training datasets and varied sizes of label fractions. MICLe is able to match baselines using only 20% of the training data for ResNet-50 (4x).

Conclusion
Supervised pre-training on natural image datasets is commonly used to improve medical image classification. We investigate an alternative strategy based on self-supervised pre-training on unlabeled natural and medical images and find that it can significantly improve upon supervised pre-training, the standard paradigm for training medical image analysis models. This approach can lead to models that are more accurate and label efficient and are robust to distribution shifts. In addition, our proposed Multi-Instance Contrastive Learning method (MICLe) enables the use of additional metadata to create realistic augmentations, yielding further performance boost of image classifiers.

Self-supervised pre-training is much more scalable than supervised pre-training because class label annotation is not required. We hope this paper will help popularize the use of self-supervised approaches in medical image analysis yielding label efficient and robust models suited for clinical deployment at scale in the real world.

Acknowledgements
This work involved collaborative efforts from a multidisciplinary team of researchers, software engineers, clinicians, and cross-functional contributors across Google Health and Google Brain. We thank our co-authors: Basil Mustafa, Fiona Ryan, Zach Beaver, Jan Freyberg, Jon Deaton, Aaron Loh, Alan Karthikesalingam, Simon Kornblith, Ting Chen, Vivek Natarajan, and Mohammad Norouzi. We also thank Yuan Liu from Google Health for valuable feedback and our partners for access to the datasets used in the research.

Source: Google AI Blog


Revisiting Mask-Head Architectures for Novel Class Instance Segmentation

Instance segmentation is the task of grouping pixels in an image into instances of individual things, and identifying those things with a class label (countable objects such as people, animals, cars, etc., and assigning unique identifiers to each, e.g., car_1 and car_2). As a core computer vision task, it is critical to many downstream applications, such as self-driving cars, robotics, medical imaging, and photo editing. In recent years, deep learning has made significant strides in solving the instance segmentation problem with architectures like Mask R-CNN. However, these methods rely on collecting a large labeled instance segmentation dataset. But unlike bounding box labels, which can be collected in 7 seconds per instance with methods like Extreme clicking, collecting instance segmentation labels (called “masks”) can take up to 80 seconds per instance, an effort that is costly and creates a high barrier to entry for this research. And a related task, pantopic segmentation, requires even more labeled data.

The partially supervised instance segmentation setting, where only a small set of classes are labeled with instance segmentation masks and the remaining (majority of) classes are labeled only with bounding boxes, is an approach that has the potential to reduce the dependence on manually-created mask labels, thereby significantly lowering the barriers to developing an instance segmentation model. However this partially supervised approach also requires a stronger form of model generalization to handle novel classes not seen at training time—e.g., training with only animal masks and then tasking the model to produce accurate instance segmentations for buildings or plants. Further, naïve approaches, such as training a class-agnostic Mask R-CNN, while ignoring mask losses for any instances that don’t have mask labels, have not worked well. For example, on the typical “VOC/Non-VOC” benchmark, where one trains on masks for a subset of 20 classes in COCO (called “seen classes”) and is tested on the remaining 60 classes (called “unseen classes”), a typical Mask R-CNN with Resnet-50 backbone gets to only ~18% mask mAP (mean Average Precision, higher is better) on unseen classes, whereas when fully supervised it can achieve a much higher >34% mask mAP on the same set.

In “The surprising impact of mask-head architecture on novel class segmentation”, to be presented at ICCV 2021, we identify the main culprits for Mask R-CNN’s poor performance on novel classes and propose two easy-to-implement fixes (one training protocol fix, one mask-head architecture fix) that work in tandem to close the gap to fully supervised performance. We show that our approach applies generally to crop-then-segment models, i.e., a Mask R-CNN or Mask R-CNN-like architecture that computes a feature representation of the entire image and then subsequently passes per-instance crops to a second-stage mask prediction network—also called a mask-head network. Putting our findings together, we propose a Mask R-CNN–based model that improves over the current state-of-the-art by a significant 4.7% mask mAP without requiring more complex auxiliary loss functions, offline trained priors, or weight transfer functions proposed by previous work. We have also open sourced the code bases for two versions of the model, called Deep-MAC and Deep-MARC, and published a colab to interactively produce masks like the video demo below.

A demo of our model, DeepMAC, which learns to predict accurate masks, given user specified boxes, even on novel classes that were not seen at training time. Try it yourself in the colab. Image credits: Chris Briggs, Wikipedia and Europeana.

Impact of Cropping Methodology in Partially Supervised Settings
An important step of crop-then-segment models is cropping—Mask R-CNN is trained by cropping a feature map as well as the ground truth mask to a bounding box corresponding to each instance. These cropped features are passed to another neural network (called a mask-head network) that computes a final mask prediction, which is then compared against the ground truth crop in the mask loss function. There are two choices for cropping: (1) cropping directly to the ground truth bounding box of an instance, or (2) cropping to bounding boxes predicted by the model (called, proposals). At test time, cropping is always performed with proposals as ground truth boxes are not assumed to be available.

Cropping to ground truth boxes vs. cropping to proposals predicted by a model during training. Standard Mask R-CNN implementations use both types of crops, but we show that cropping exclusively to ground truth boxes yields significantly stronger performance on novel categories.
We consider a general family of Mask R-CNN–like architectures with one small, but critical difference from typical Mask R-CNN training setups: we crop using ground truth boxes (instead of proposal boxes) at training time.

Typical Mask R-CNN implementations pass both types of crops to the mask head. However, this choice has traditionally been considered an unimportant implementation detail, because it does not affect performance significantly in the fully supervised setting. In contrast, for partially supervised settings, we find that cropping methodology plays a significant role—while cropping exclusively to ground truth boxes during training doesn’t change the results significantly in the fully supervised setting, it has a surprising and dramatic positive impact in the partially supervised setting, performing significantly better on unseen classes.

Performance of Mask R-CNN on unseen classes when trained with either proposals and ground truth (the default) or with only ground truth boxes. Training mask heads with only ground truth boxes yields a significant boost to performance on unseen classes, upwards of 9% mAP. We report performance with the ResNet-101-FPN backbone.

Unlocking the Full Generalization Potential of the Mask Head
Even more surprisingly, the above approach unlocks a novel phenomenon—with cropping-to-ground truth enabled during training, the mask head of Mask R-CNN takes on a disproportionate role in the ability of the model to generalize to unseen classes. As an example, in the following figure, we compare models that all have cropping-to-ground-truth enabled, but different out-of-the-box mask-head architectures on a parking meter, cell phone, and pizza (classes unseen during training).

Mask predictions for unseen classes with four different mask-head architectures (from left to right: ResNet-4, ResNet-12, ResNet-20, Hourglass-20, where the number refers to the number of layers of the neural network). Despite never having seen masks from the ‘parking meter’, ‘pizza’ or ‘mobile phone’ class, the rightmost mask-head architecture can segment these classes correctly. From left to right, we show better mask-head architectures predicting better masks. Moreover, this difference is only apparent when evaluating on unseen classes — if we evaluate on seen classes, all four architectures exhibit similar performance.

Particularly notable is that these differences between mask-head architectures are not as obvious in the fully supervised setting. Incidentally, this may explain why previous works in instance segmentation have almost exclusively used shallow (i.e., low number of layers) mask heads, as there has been no benefit to the added complexity. Below we compare the mask mAP of three different mask-head architectures on seen versus unseen classes. All three models do equally well on the set of seen classes, but the deep hourglass mask heads stand out when applied to unseen classes. We find hourglass mask heads to be the best among the architectures we tried and we use hourglass mask heads with 50 or more layers to get the best results.

Performance of ResNet-4, Hourglass-10 and Hourglass-52 mask-head architectures on seen and unseen classes. There is a significant difference in performance on unseen classes, even though the performance on seen classes barely changes.

Finally, we show that our findings are general, holding for a variety of backbones (e.g., ResNet, SpineNet, Hourglass) and detector architectures including anchor-based and anchor-free detectors and even when there is no detector at all.

Putting It Together
To achieve the best result, we combined the above findings: We trained a Mask R-CNN model with cropping-to-ground-truth enabled and a deep Hourglass-52 mask head with a SpineNet backbone on high resolution images (1280x1280). We call this model Deep-MARC (Deep Mask heads Above R-CNN). Without using any offline training or other hand-crafted priors, Deep-MARC exceeds previous state-of-the-art models by > 4.5% (absolute) mask mAP. Demonstrating the general nature of this approach, we also see strong results with a CenterNet-based (as opposed to Mask R-CNN-based) model (called Deep-MAC), which also exceeds the previous state of the art.

Comparison of Deep-MAC and Deep-MARC to other partially supervised instance segmentation approaches like MaskX R-CNN, ShapeMask and CPMask.

Conclusion
We develop instance segmentation models that are able to generalize to classes that were not part of the training set. We highlight the role of two key ingredients that can be applied to any crop-then-segment model (such as Mask R-CNN): (1) cropping-to-ground truth boxes during training, and (2) strong mask-head architectures. While neither of these ingredients have a large impact on the classes for which masks are available during training, employing both leads to significant improvement on novel classes for which masks are not available during training. Moreover, these ingredients are sufficient for achieving state-of-the-art-performance on the partially-supervised COCO benchmark. Finally, our findings are general and may also have implications for related tasks, such as panoptic segmentation and pose estimation.

Acknowledgements
We thank our co-authors Zhichao Lu, Siyang Li, and Vivek Rathod. We thank David Ross and our anonymous ICCV reviewers for their comments which played a big part in improving this research.

Source: Google AI Blog


Music Conditioned 3D Dance Generation with AIST++

Dancing is a universal language found in nearly all cultures, and is an outlet many people use to express themselves on contemporary media platforms today. The ability to dance by composing movement patterns that align to music beats is a fundamental aspect of human behavior. However, dancing is a form of art that requires practice. In fact, professional training is often required to equip a dancer with a rich repertoire of dance motions needed to create expressive choreography. While this process is difficult for people, it is even more challenging for a machine learning (ML) model, because the task requires the ability to generate a continuous motion with high kinematic complexity, while capturing the non-linear relationship between the movements and the accompanying music.

In “AI Choreographer: Music-Conditioned 3D Dance Generation with AIST++”, presented at ICCV 2021, we propose a full-attention cross-modal Transformer (FACT) model can mimic and understand dance motions, and can even enhance a person’s ability to choreograph dance. Together with the model, we released a large-scale, multi-modal 3D dance motion dataset, AIST++, which contains 5.2 hours of 3D dance motion in 1408 sequences, covering 10 dance genres, each including multi-view videos with known camera poses. Through extensive user studies on AIST++, we find that the FACT model outperforms recent state-of-the-art methods, both qualitatively and quantitatively.

We present a novel full-attention cross-modal transformer (FACT) network that can generate realistic 3D dance motion (right) conditioned on music and a new 3D dance dataset, AIST++ (left).

We generate the proposed 3D motion dataset from the existing AIST Dance Database — a collection of videos of dance with musical accompaniment, but without any 3D information. AIST contains 10 dance genres: Old School (Break, Pop, Lock and Waack) and New School (Middle Hip-Hop, LA-style Hip-Hop, House, Krump, Street Jazz and Ballet Jazz). Although it contains multi-view videos of dancers, these cameras are not calibrated.

For our purposes, we recovered the camera calibration parameters and the 3D human motion in terms of parameters used by the widely used SMPL 3D model. The resulting database, AIST++, is a large-scale, 3D human dance motion dataset that contains a wide variety of 3D motion, paired with music. Each frame includes extensive annotations:

  • 9 views of camera intrinsic and extrinsic parameters;
  • 17 COCO-format human joint locations in both 2D and 3D;
  • 24 SMPL pose parameters along with the global scaling and translation.

The motions are equally distributed among all 10 dance genres, covering a wide variety of music tempos in beat per minute (BPM). Each genre of dance contains 85% basic movements and 15% advanced movements (longer choreographies freely designed by the dancers).

The AIST++ dataset also contains multi-view synchronized image data, making it useful for other research directions, such as 2D/3D pose estimation. To our knowledge, AIST++ is the largest 3D human dance dataset with 1408 sequences, 30 subjects and 10 dance genres, and with both basic and advanced choreographies.

An example of a 3D dance sequence in the AIST++ dataset. Left: Three views of the dance video from the AIST database. Right: Reconstructed 3D motion visualized in 3D mesh (top) and skeletons (bottom).

Because AIST is an instructional database, it records multiple dancers following the same choreography for different music with varying BPM, a common practice in dance. This posits a unique challenge in cross-modal sequence-to-sequence generation as the model needs to learn the one-to-many mapping between audio and motion. We carefully construct non-overlapping train and test subsets on AIST++ to ensure neither choreography nor music is shared across the subsets.

Full Attention Cross-Modal Transformer (FACT) Model
Using this data, we train the FACT model to generate 3D dance from music. The model begins by encoding seed motion and audio inputs using separate motion and audio transformers. The embeddings are then concatenated and sent to a cross-modal transformer, which learns the correspondence between both modalities and generates N future motion sequences. These sequences are then used to train the model in a self-supervised manner. All three transformers are jointly learned end-to-end. At test time, we apply this model in an autoregressive framework, where the predicted motion serves as the input to the next generation step. As a result, the FACT model is capable of generating long range dance motion frame-by-frame.

The FACT network takes in a music piece (Y) and a 2-second sequence of seed motion (X), then generates long-range future motions that correlate with the input music.

FACT involves three key design choices that are critical for producing realistic 3D dance motion from music.

  1. All of the transformers use a full-attention mask, which can be more expressive than typical causal models because internal tokens have access to all inputs.
  2. We train the model to predict N futures beyond the current input, instead of just the next motion. This encourages the network to pay more attention to the temporal context, and helps prevent the model from motion freezing or diverging after a few generation steps.
  3. We fuse the two embeddings (motion and audio) early and employ a deep 12-layer cross-modal transformer module, which is essential for training a model that actually pays attention to the input music.

Results
We evaluate the performance based on three metrics:

Motion Quality: We calculate the Frechet Inception Distance (FID) between the real dance motion sequences in the AIST++ test set and 40 model generated motion sequences, each with 1200 frames (20 secs). We denote the FID based on the geometric and kinetic features as FIDg and FIDk, respectively.

Generation Diversity: Similar to prior work, to evaluate the model’s ability to generate divers dance motions, we calculate the average Euclidean distance in the feature space across 40 generated motions on the AIST++ test set, again comparing geometric feature space (Distg) and in the kinetic feature space (Distk).

Four different dance choreographies (right) generated using different music, but the same two second seed motion (left). The genres of the conditioning music are: Break, Ballet Jazz, Krump and Middle Hip-hop. The seed motion comes from hip-hop dance.

Motion-Music Correlation: Because there is no well-designed metric to measure the correlation between input music (music beats) and generated 3D motion (kinematic beats), we propose a novel metric, called Beat Alignment Score (BeatAlign).

Kinetic velocity (blue curve) and kinematic beats (green dotted line) of the generated dance motion, as well as the music beats (orange dotted line). The kinematic beats are extracted by finding local minima from the kinetic velocity curve.

Quantitative Evaluation
We compare the performance of FACT on each of these metrics to that of other state-of-the-art methods.

Compared to three recent state-of-the-art methods (Li et al., Dancenet, and Dance Revolution), the FACT model generates motions that are more realistic, better correlated with input music, and more diversified when conditioned on different music. *Note that the Li et al. generated motions are discontinuous, making the average kinetic feature distance abnormally high.

We also perceptually evaluate the motion-music correlation with a user study in which each participant is asked to watch 10 videos showing one of our results and one random counterpart, and then select which dancer is more in sync with the music. The study consisted of 30 participants, ranging from professional dancers to people who rarely dance. Compared to each baseline, 81% prefered the FACT model output to that of Li et al., 71% prefered FACT to Dancenet, and 77% prefered it Dance Revolution. Interestingly, 75% of participants preferred the unpaired AIST++ dance motion to that generated by FACT, which is unsurprising since the original dance captures are highly expressive.

Qualitative Results
Compared with prior methods like DanceNet (left) and Li et. al. (middle), 3D dance generated using the FACT model (right) is more realistic and better correlated with input music.

More generated 3D dances using the FACT model.

Conclusion and Discussion
We present a model that can not only learn the audio-motion correspondence, but also can generate high quality 3D motion sequences conditioned on music. Because generating 3D movement from music is a nascent area of study, we hope our work will pave the way for future cross-modal audio to 3D motion generation. We are also releasing AIST++, the largest 3D human dance dataset to date. This proposed, multi-view, multi-genre, cross-modal 3D motion dataset can not only help research in the conditional 3D motion generation research but also human understanding research in general. We are releasing the code in our GitHub repository and the trained model here.

While our results show a promising direction in this problem of music conditioned 3D motion generation, there are more to be explored. First, our approach is kinematic-based and we do not reason about physical interactions between the dancer and the floor. Therefore the global translation can lead to artifacts, such as foot sliding and floating. Second, our model is currently deterministic. Exploring how to generate multiple realistic dances per music is an exciting direction.

Acknowledgements
We gratefully acknowledge the contribution of other co-authors, including Ruilong Li and David Ross. We thank Chen Sun, Austin Myers, Bryan Seybold and Abhijit Kundu for helpful discussions. We thank Emre Aksan and Jiaman Li for sharing their code. We also thank Kevin Murphy for the early attempts in this direction, as well as Peggy Chi and Pan Chen for the help on user study experiments.

Source: Google AI Blog


Google at ICCV 2019



This week, Seoul, South Korea hosts the International Conference on Computer Vision 2019 (ICCV 2019), one of the world's premier conferences on computer vision. As a leader in computer vision research and a Gold Sponsor, Google will have a strong presence at ICCV 2019 with over 200 Googlers in attendance, more than 40 research presentations, and involvement in the organization of a number of workshops and tutorials.

If you are attending ICCV this year, please stop by our booth. There you can chat with researchers who are actively pursuing the latest innovations in computer vision and demo some of their latest research, including the technology behind MediaPipe, the new Open Images dataset, new developments for Google Lens and much more.

This year Google researchers are recipients of three prestigious ICCV awards:
More details about the Google research being presented at ICCV 2019 can be found below (Google affiliations in blue).

Organizing Committee includes:
Ming-Hsuan Yang (Program Chair)

Oral Presentations
Learning Single Camera Depth Estimation using Dual-Pixels
Rahul Garg, Neal Wadhwa, Sameer Ansari, Jonathan Barron 

RIO: 3D Object Instance Re-Localization in Changing Indoor Environments
Johanna Wald, Armen Avetisyan, Nassir Navab, Federico Tombari, Matthias Niessner 

ShapeMask: Learning to Segment Novel Objects by Refining Shape Priors
Weicheng Kuo, Anelia Angelova, Jitendra Malik, Tsung-Yi Lin 

PuppetGAN: Cross-Domain Image Manipulation by Demonstration
Ben Usman, Nick Dufour, Kate Saenko, Chris Bregler

COCO-GAN: Generation by Parts via Conditional Coordinating
Chieh Hubert Lin, Chia-Che Chang, Yu-Sheng Chen, Da-Cheng Juan, Wei Wei, Hwann-Tzong Chen

Towards Unconstrained End-to-End Text Spotting
Siyang Qin, Alessandro Bissaco, Michalis Raptis, Yasuhisa Fujii, Ying Xiao

SinGAN: Learning a Generative Model from a Single Natural Image
Tamar Rott Shaham, Tali Dekel, Tomer Michaeli 
(ICCV 2019 Marr Prize Winner — Best Paper Award)

Generative Modeling for Small-Data Object Detection
Lanlan Liu, Michael Muelly, Jia Deng, Tomas Pfister, Li-Jia Li 

Searching for MobileNetV3
Andrew Howard, Mark Sandler, Bo Chen, Weijun Wang, Liang-Chieh Chen, Mingxing Tan, Grace Chu, Vijay Vasudevan, Yukun Zhu, Ruoming Pang, Hartwig Adam, Quoc Le 

S⁴L: Self-Supervised Semi-supervised Learning
Lucas Beyer, Xiaohua Zhai, Avital Oliver, Alexander Kolesnikov 

Sampling-Free Epistemic Uncertainty Estimation Using Approximated Variance Propagation
Janis Postels, Francesco Ferroni, Huseyin Coskun, Nassir Navab, Federico Tombari

Linearized Multi-sampling for Differentiable Image Transformation
Wei Jiang, Weiwei Sun, Andrea Tagliasacchi, Eduard Trulls, Kwang Moo Yi 

Poster Presentations
ELF: Embedded Localisation of Features in Pre-trained CNN
Assia Benbihi, Matthieu Geist, Cedric Pradalier 

Depth from Videos in the Wild: Unsupervised Monocular Depth Learning from Unknown Cameras
Ariel Gordon, Hanhan Li, Rico Jonschkowski, Anelia Angelova

ForkNet: Multi-branch Volumetric Semantic Completion from a Single Depth Image
Yida Wang, David Joseph Tan, Nassir Navab, Federico Tombari 

A Learned Representation for Scalable Vector Graphics
Raphael Gontijo Lopes, David Ha, Douglas Eck, Jonathon Shlens 

FrameNet: Learning Local Canonical Frames of 3D Surfaces from a Single RGB Image
Jingwei Huang, Yichao Zhou, Thomas Funkhouser, Leonidas Guibas

Prior-Aware Neural Network for Partially-Supervised Multi-Organ Segmentation
Yuyin Zhou, Zhe Li, Song Bai, Xinlei Chen, Mei Han, Chong Wang, Elliot Fishman, Alan Yuille 

Boundless: Generative Adversarial Networks for Image Extension
Dilip Krishnan, Piotr Teterwak, Aaron Sarna, Aaron Maschinot, Ce Liu, David Belanger, William Freeman

Cap2Det: Learning to Amplify Weak Caption Supervision for Object Detection
Keren Ye, Mingda Zhang, Adriana Kovashka, Wei Li, Danfeng Qin, Jesse Berent 

NOTE-RCNN: NOise Tolerant Ensemble RCNN for Semi-supervised Object Detection
Jiyang Gao, Jiang Wang, Shengyang Dai, Li-Jia Li, Ram Nevatia 

Object-Driven Multi-Layer Scene Decomposition from a Single Image
Helisa Dhamo, Nassir Navab, Federico Tombari 

Improving Adversarial Robustness via Guided Complement Entropy
Hao-Yun Chen, Jhao-Hong Liang, Shih-Chieh Chang, Jia-Yu Pan, Yu-Ting Chen, Wei Wei, Da-Cheng Juan 

XRAI: Better Attributions Through Regions
Andrei Kapishnikov, Tolga Bolukbasi, Fernanda Viegas, Michael Terry

SegSort: Segment Sorting for Semantic Segmentation
Jyh-Jing Hwang, Stella Yu, Jianbo Shi, Maxwell Collins, Tien-Ju Yang, Xiao Zhang, Liang-Chieh Chen 

Self-Supervised Learning with Geometric Constraints in Monocular Video: Connecting Flow, Depth, and Camera
Yuhua Chen, Cordelia Schmid, Cristian Sminchisescu 

VideoBERT: A Joint Model for Video and Language Representation Learning
Chen Sun, Austin Myers, Carl Vondrick, Kevin Murphy, Cordelia Schmid 

Explaining the Ambiguity of Object Detection and 6D Pose from Visual Data
Fabian Manhardt, Diego Martín Arroyo, Christian Rupprecht, Benjamin  Busam, Tolga Birdal, Nassir Navab, Federico Tombari 

Constructing Self-Motivated Pyramid Curriculums for Cross-Domain Semantic Segmentation
Qing Lian, Lixin Duan, Fengmao Lv, Boqing Gong 

Learning Shape Templates Using Structured Implicit Functions
Kyle Genova, Forrester Cole, Daniel Vlasic, Aaron Sarna, William Freeman, Thomas Funkhouser

Transferable Representation Learning in Vision-and-Language Navigation
Haoshuo Huang, Vihan Jain, Harsh Mehta, Alexander Ku, Gabriel Magalhaes, Jason Baldridge, Eugene Ie 

Controllable Attention for Structured Layered Video Decomposition
Jean-Baptiste Alayrac, Joao Carreira, Relja Arandjelović, Andrew Zisserman

Pixel2Mesh++: Multi-view 3D Mesh Generation via Deformation
Chao Wen, Yinda Zhang, Zhuwen Li, Yanwei Fu

Beyond Cartesian Representations for Local Descriptors
Patrick Ebel, Anastasiia Mishchuk, Kwang Moo Yi, Pascal Fua, Eduard Trulls

Domain Randomization and Pyramid Consistency: Simulation-to-Real Generalization without Accessing Target Domain Data
Xiangyu Yue, Yang Zhang, Sicheng Zhao, Alberto Sangiovanni-Vincentelli, Kurt Keutzer, Boqing Gong 

Evolving Space-Time Neural Architectures for Videos
AJ Piergiovanni, Anelia Angelova, Alexander Toshev, Michael Ryoo 

Moulding Humans: Non-parametric 3D Human Shape Estimation from Single Images
Valentin Gabeur, Jean-Sebastien Franco, Xavier Martin, Cordelia Schmid, Gregory Rogez

Multi-view Image Fusion
Marc Comino Trinidad, Ricardo Martin-Brualla, Florian Kainz, Janne Kontkanen 

EvalNorm: Estimating Batch Normalization Statistics for Evaluation
Saurabh Singh, Abhinav Shrivastava

Attention Augmented Convolutional Networks
Irwan Bello, Barret Zoph, Quoc Le, Ashish Vaswani, Jonathon Shlens 

Patchwork: A Patch-wise Attention Network for Efficient Object Detection and Segmentation in Video Streams
Yuning Chai

Workshops
Low-Power Computer Vision
Organizers include: Bo Chen

Neural Architects
Organizers include: Barret Zoph

The 3rd YouTube-8M Large-Scale Video Understanding Workshop
Organizers include: Paul NatsevCordelia SchmidRahul SukthankarJoonseok LeeGeorge Toderici

Should We Pre-register Experiments in Computer Vision?
Organizers include: Jack Valmadre

Extreme Vision Modeling
Organizers include: Rahul Sukthankar

Joint COCO and Mapillary Recognition Challenge
Organizers include: Tsung-Yi Lin, Yin Cui

Open Images Challenge
Organizers include: Vittorio Ferrari, Alina Kuznetsova, Rodrigo Benenson, Victor Gomes, Matteo Malloci

Tutorials
Meta-Learning and Metric Learning Algorithms
Organizers include: Kevin Swersky

Source: Google AI Blog


Announcing the YouTube-8M Segments Dataset



Over the last two years, the First and Second YouTube-8M Large-Scale Video Understanding Challenge and Workshop have collectively drawn 1000+ teams from 60+ countries to further advance large-scale video understanding research. While these events have enabled great progress in video classification, the YouTube dataset on which they were based only used machine-generated video-level labels, and lacked fine-grained temporally localized information, which limited the ability of machine learning models to predict video content.

To accelerate the research of temporal concept localization, we are excited to announce the release of YouTube-8M Segments, a new extension of the YouTube-8M dataset that includes human-verified labels at the 5-second segment level on a subset of YouTube-8M videos. With the additional temporal annotations, YouTube-8M is now both a large-scale classification dataset as well as a temporal localization dataset. In addition, we are hosting another Kaggle video understanding challenge focused on temporal localization, as well as an affiliated 3rd Workshop on YouTube-8M Large-Scale Video Understanding at the 2019 International Conference on Computer Vision (ICCV’19).



YouTube-8M Segments
Video segment labels provide a valuable resource for temporal localization not possible with video-level labels, and enable novel applications, such as capturing special video moments. Instead of exhaustively labeling all segments in a video, to create the YouTube-8M Segments extension, we manually labeled 5 segments (on average) per randomly selected video on the YouTube-8M validation dataset, totalling ~237k segments covering 1000 categories.

This dataset, combined with the previous YouTube-8M release containing a very large number of machine generated video-level labels, should allow learning temporal localization models in novel ways. Evaluating such classifiers is of course very challenging if only noisy video-level labels are available. We hope that the newly added human-labeled annotations will help ensure that researchers can more accurately evaluate their algorithms.

The 3rd YouTube-8M Video Understanding Challenge
This year the YouTube-8M Video Understanding Challenge focuses on temporal localization. Participants are encouraged to leverage noisy video-level labels together with a small segment-level validation set in order to better annotate and temporally localize concepts of interest. Unlike last year, there is no model size restriction. Each of the top 10 teams will be awarded $2,500 to support their travel to Seoul to attend ICCV’19. For details, please visit the Kaggle competition page.

The 3rd Workshop on YouTube-8M Large-Scale Video Understanding
Continuing in the tradition of the previous two years, the 3rd workshop will feature four invited talks by distinguished researchers as well as presentations by top-performing challenge participants. We encourage those who wish to attend to submit papers describing their research, experiments, or applications based on the YouTube-8M dataset, including papers summarizing their participation in the challenge above. Please refer to the workshop page for more details.

It is our hope that this newest extension will serve as a unique playground for temporal localization that mimics real world scenarios. We also look forward to the new challenge and workshop, which we believe will continue to advance research in large-scale video understanding. We hope you will join us again!

Acknowledgements
This post reflects the work of many machine perception researchers including Ke Chen, Nisarg Kothari, Joonseok Lee, Hanhan Li, Paul Natsev, Joe Yue-Hei Ng, Naderi Parizi, David Ross, Cordelia Schmid, Javier Snaider, Rahul Sukthankar, George Toderici, Balakrishnan Varadarajan, Sudheendra Vijayanarasimhan, Yexin Wang, Zheng Xu, as well as Julia Elliott and Walter Reade from Kaggle. We are also grateful for the support and advice from our partners at YouTube.

Source: Google AI Blog


Announcing Open Images V5 and the ICCV 2019 Open Images Challenge



In 2016, we introduced Open Images, a collaborative release of ~9 million images annotated with labels spanning thousands of object categories. Since then we have rolled out several updates, culminating with Open Images V4 in 2018. In total, that release included 15.4M bounding-boxes for 600 object categories, making it the largest existing dataset with object location annotations, as well as over 300k visual relationship annotations.

Today we are happy to announce Open Images V5, which adds segmentation masks to the set of annotations, along with the second Open Images Challenge, which will feature a new instance segmentation track based on this data.

Open Images V5
Open Images V5 features segmentation masks for 2.8 million object instances in 350 categories. Unlike bounding-boxes, which only identify regions in which an object is located, segmentation masks mark the outline of objects, characterizing their spatial extent to a much higher level of detail. We have put particular effort into ensuring consistent annotations across different objects (e.g., all cat masks include their tail; bags carried by camels or persons are included in their mask). Importantly, these masks cover a broader range of object categories and a larger total number of instances than any previous dataset.

Example masks on the training set of Open Images V5. These have been produced by our interactive segmentation process. The first example also shows a bounding box, for comparison. From left to right, top to bottom: Tea and cake at the Fitzwilliam Museum by Tim Regan, Pilota II by Euskal kultur erakundea Institut culturel basque, Rheas by Dag Peak, Wuxi science park, 1995 by Gary Stevens, Cat Cafe Shinjuku calico by Ari Helminen, and Untitled by Todd Huffman. All images used under CC BY 2.0 license.
The segmentation masks on the training set (2.68M) have been produced by our state-of-the-art interactive segmentation process, where professional human annotators iteratively correct the output of a segmentation neural network. This is more efficient than manual drawing alone, while at the same time delivering accurate masks (intersection-over-union 84%). Additionally, we release 99k masks on the validation and test sets, which have been annotated manually with a strong focus on quality. These are near-perfect and capture even fine details of complex object boundaries (e.g. spiky flowers and thin structures in man-made objects). Both our training and validation+test annotations offer more accurate object boundaries than the polygon annotations provided by most existing datasets.

Example masks on the validation and test sets of Open Images V5, drawn completely manually. From left to right: thistle flowers by sophie, still life with ax by liz west, Fischkutter KOŁ-180 in Kolobrzeg (PL) by zeesenboot. All images used under CC BY 2.0 license.
In addition to the masks, we also added 6.4M new human-verified image-level labels, reaching a total of 36.5M over nearly 20,000 categories. Finally, we improved annotation density for 600 object categories on the validation and test sets, adding more than 400k bounding boxes to match the density in the training set. This ensures more precise evaluation of object detection models.

Open Images Challenge 2019
In conjunction with this release, we are also introducing the second Open Images Challenge, to be held at the 2019 International Conference on Computer Vision (ICCV 2019). This Challenge will have a new instance segmentation track based on the data above. Moreover, as in the 2018 edition, it will also feature a large-scale object detection track (500 categories with 12.2M training bounding-boxes), and a visual relationship detection track for detecting pairs of objects in particular relations (329 relationship triplets with 375k training samples, e.g., “woman playing guitar” or “beer on table”).

The training set with all annotations is available now. The test set has the same 100k images as the 2018 Challenge and will be launched again on June 3rd, 2019 by Kaggle. The evaluation servers will open on June 3rd for the object detection and visual relationship tracks, and on July 1st for the instance segmentation track. The deadline for submission of results is October 1st, 2019.

We hope that the exceptionally large and diverse training set will inspire research into more advanced instance segmentation models. The extremely accurate ground-truth masks we provide rewards subtle improvements in the output segmentations, and thus will encourage the development of higher-quality models that deliver precise boundaries. Finally, having a single dataset with unified annotations for image classification, object detection, visual relationship detection, and instance segmentation will enable researchers to study these tasks jointly and stimulate progress towards genuine scene understanding.

Source: Google AI Blog