Visual Intelligence and Learning Laboratory (VILAB)

We are a research group at the Swiss Federal Institute of Technology (EPFL)'s School of Computer and Communication Sciences (IC). Our research focus is broadly on Computer Vision, Machine Learning, and Perception-for-Robotics.




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Highlighted Recent Projects

MultiMAE: Multi-modal Multi-task Masked Autoencoders
R. Bachmann*, D. Mizrahi*, A. Atanov, A. Zamir
ArXiv, 2022.
[project website] [code] [PDF]

We propose a pre-training strategy called Multi-modal Multi-task Masked Autoencoders (MultiMAE). It differs from standard Masked Autoencoding in two key aspects: I) it can optionally accept additional modalities of information in the input besides the RGB image (hence "multi-modal"), and II) its training objective accordingly includes predicting multiple outputs besides the RGB image (hence "multi-task"). We make use of masking (across image patches and input modalities) to make training MultiMAE tractable as well as to ensure cross-modality predictive coding is indeed learned by the network. We show this pre-training strategy leads to a flexible, simple, and efficient framework with improved transfer results to downstream tasks. In particular, the same exact pre-trained network can be flexibly used when additional information besides RGB images is available or when no information other than RGB is available - in all configurations yielding competitive to or significantly better results than the baselines. To avoid needing training datasets with multiple modalities and tasks, we train MultiMAE entirely using pseudo labeling, which makes the framework widely applicable to any RGB dataset. The experiments are performed on multiple transfer tasks (image classification, semantic segmentation, depth estimation) and datasets (ImageNet, ADE20K, Taskonomy, Hypersim, NYUv2). The results show an intriguingly impressive capability by the model in cross-modal/task predictive coding and transfer.

3D Common Corruptions and Data Augmentation
O.F. Kar, T. Yeo, A. Atanov, A. Zamir
CVPR, 2022. [Oral]
[project website] [code] [PDF]

We introduce a set of image transformations that can be used as corruptions to evaluate the robustness of models as well as data augmentation mechanisms for training neural networks. The primary distinction of the proposed transformations is that, unlike existing approaches such as Common Corruptions, the geometry of the scene is incorporated in the transformations -- thus leading to corruptions that are more likely to occur in the real world. We also introduce a set of semantic corruptions (e.g. natural object occlusions).

We show these transformations are `efficient' (can be computed on-the-fly), `extendable' (can be applied on most image datasets), expose vulnerability of existing models, and can effectively make models more robust when employed as `3D data augmentation' mechanisms. The evaluations on several tasks and datasets suggest incorporating 3D information into benchmarking and training opens up a promising direction for robustness research.

CLIPasso: Semantically-Aware Object Sketching
Y. Vinker, E. Pajouheshgar, J. Y. Bo, R. Bachmann, A. H. Bermano, D. Cohen-Or, A. Zamir, A. Shamir
Transactions on Graphics (Proceedings of SIGGRAPH), 2022.
[project website] [code] [PDF]

Abstraction is at the heart of sketching due to the simple and minimal nature of line drawings. Abstraction entails identifying the essential visual properties of an object or scene, which requires semantic understanding and prior knowledge of high-level concepts. Abstract depictions are therefore challenging for artists, and even more so for machines. We present an object sketching method that can achieve different levels of abstraction, guided by geometric and semantic simplifications. While sketch generation methods often rely on explicit sketch datasets for training, we utilize the remarkable ability of CLIP (Contrastive-Language-Image-Pretraining) to distill semantic concepts from sketches and images alike. We define a sketch as a set of Bézier curves and use a differentiable rasterizer to optimize the parameters of the curves directly with respect to a CLIP-based perceptual loss. The abstraction degree is controlled by varying the number of strokes. The generated sketches demonstrate multiple levels of abstraction while maintaining recognizability, underlying structure, and essential visual components of the subject drawn.

Robustness via Cross-Domain Ensembles
T. Yeo*, O.F. Kar*, A. Zamir
ICCV, 2021. [Oral]
[project website] [code] [PDF]

We present a method for making neural network predictions robust to shifts from the training data distribution. The proposed method is based on making predictions via a diverse set of cues (called 'middle domains') and ensembling them into one strong prediction. The premise of the idea is that predictions made via different cues respond differently to a distribution shift, hence one should be able to merge them into one robust final prediction. We perform the merging in a straightforward but principled manner based on the uncertainty associated with each prediction. The evaluations are performed using multiple tasks and datasets (Taskonomy, Replica, ImageNet, CIFAR) under a wide range of adversarial and non-adversarial distribution shifts which demonstrate the proposed method is considerably more robust than its standard learning counterpart, conventional deep ensembles, and several other baselines.

Omnidata: A Scalable Pipeline for Making Multi-Task Mid-Level Vision Datasets from 3D Scans
A. Eftekhar*, A. Sax*, R. Bachmann, J. Malik, A. Zamir
ICCV, 2021.
[project website] [live demo] [code] [PDF]

This paper introduces a pipeline to parametrically sample and render multi-task vision datasets from comprehensive 3D scans from the real world. Changing the sampling parameters allows one to "steer" the generated datasets to emphasize specific information. In addition to enabling interesting lines of research, we show the tooling and generated data suffice to train robust vision models. Common architectures trained on a generated starter dataset reached state-of-the-art performance on multiple common vision tasks and benchmarks, despite having seen no benchmark or non-pipeline data. The depth estimation network outperforms MiDaS and the surface normal estimation network is the first to achieve human-level performance for in-the-wild surface normal estimation -- at least according to one metric on the OASIS benchmark. The Dockerized pipeline with CLI, the (mostly python) code, PyTorch dataloaders for the generated data, the generated starter dataset, download scripts and other utilities are available through our project website, https://omnidata.vision.

Robust Learning Through Cross-Task Consistency
A. Zamir*, A. Sax*, T. Yeo, O. Kar, N. Cheerla, R. Suri, J. Cao, J. Malik, L. Guibas
CVPR, 2020. [Best Paper Award Nominee]
[project website] [live demo] [code] [PDF] [slides]

Visual perception entails solving a wide set of tasks, e.g., object detection, depth estimation, etc. The predictions made for multiple tasks from the same image are not independent, and therefore, are expected to be ‘consistent’. We propose a broadly applicable and fully computational method for augmenting learning with Cross-Task Consistency. The proposed formulation is based on inference-path invariance over a graph of arbitrary tasks. We observe that learning with cross-task consistency leads to more accurate predictions and better generalization to out-of-distribution inputs. This framework also leads to an informative unsupervised quantity, called Consistency Energy, based on measuring the intrinsic consistency of the system. Consistency Energy correlates well with the supervised error (r=0.67), thus it can be employed as an unsupervised confidence metric as well as for detection of out-of-distribution inputs (ROC-AUC=0.95). The evaluations are performed on multiple datasets, including Taskonomy, Replica, CocoDoom, and ApolloScape, and they benchmark cross-task consistency versus various baselines including conventional multi-task learning, cycle consistency, and analytical consistency.

Which Tasks Should Be Learned Together in Multi-task Learning?
T. Standley, A. Zamir, D. Chen, L. Guibas, J. Malik, S. Savarese
ICML, 2020.
[project website] [slides] [code] [PDF]

Many computer vision applications require solving multiple tasks in real-time. A neural network can be trained to solve multiple tasks simultaneously using multi-task learning. This can save computation at inference time as only a single network needs to be evaluated. Unfortunately, this often leads to inferior overall performance as task objectives can compete, which consequently poses the question: which tasks should and should not be learned together in one network when employing multi-task learning? We study task cooperation and competition in several different learning settings and propose a framework for assigning tasks to a few neural networks such that cooperating tasks are computed by the same neural network, while competing tasks are computed by different networks. Our framework offers a time-accuracy trade-off and can produce better accuracy using less inference time than not only a single large multi-task neural network but also many single-task networks.

Side-tuning: Network Adaptation via Additive Side Networks
J. Zhang, A. Sax, A. Zamir, L. Guibas, J. Malik
ECCV, 2020. [Spotlight]
[project website] [code] [PDF]

When training a neural network for a desired task, one may prefer to adapt a pre-trained network rather than start with a randomly initialized one -- due to lacking enough training data, performing lifelong learning where the system has to learn a new task while being previously trained for other tasks, or wishing to encode priors in the network via preset weights. The most commonly employed approaches for network adaptation are fine-tuning and using the pre-trained network as a fixed feature extractor, among others.

In this paper we propose a straightforward alternative: Side-Tuning. Side-tuning adapts a pre-trained network by training a lightweight "side" network that is fused with the (unchanged) pre-trained network using a simple additive process. This simple method works as well as or better than existing solutions while it resolves some of the basic issues with fine-tuning, fixed features, and several other common baselines. In particular, side-tuning is less prone to overfitting when little training data is available, yields better results than using a fixed feature extractor, and does not suffer from catastrophic forgetting in lifelong learning. We demonstrate the performance of side-tuning under a diverse set of scenarios, including lifelong learning (iCIFAR, Taskonomy), reinforcement learning, imitation learning (visual navigation in Habitat), NLP question-answering (SQuAD v2), and single-task transfer learning (Taskonomy), with consistently promising results.

Robust Policies via Mid-Level Visual Representations: An Experimental Study in Manipulation and Navigation
B. Chen, S. Sax, L. Pinto, F. Lewis, I. Armeni, S. Savarese, A. Zamir, J. Malik
CoRL, 2020.
[project website] [code] [PDF]

Vision-based robotics often factors the control loop into separate components for perception and control. Conventional perception components usually extract hand-engineered features from the visual input that are then used by the control component in an explicit manner. In contrast, recent advances in deep RL make it possible to learn these features end-to-end during training, but the final result is often brittle, fails unexpectedly under minuscule visual shifts, and comes with a high sample complexity cost.

In this work, we study the effects of using mid-level visual representations asynchronously trained for traditional computer vision objectives as a generic and easy-to-decode perceptual state in an end-to-end RL framework. We show that the invariances provided by the mid-level representations aid generalization, improve sample complexity, and lead to a higher final performance. Compared to the alternative approaches for incorporating invariances, such as domain randomization, using asynchronously trained mid-level representations scale better to harder problems and larger domain shifts, and consequently, successfully trains policies for tasks where domain randomization or learning-from-scratch failed. Our experimental findings are reported on manipulation and navigation tasks using real robots as well as simulations.



Prospective Members:

  • PhD Applicants: We are always looking for highly talented and motivated students. However, you don't need to send an email first. PhD admissions at EPFL are centralized and competitive. Please directly apply to the PhD program of computer science. The admission system allows you to identify the professors/labs you're interested in. If you believe your case is a unique fit for our lab, please send an email with your CV as well, after you submit your application.
  • Postdocs: Please email Amir directly.
  • BS/MS interns and project students: If you're an EPFL student, send us an email with your CV attached. If you are not and you are eligible for Summer@EPFL internship program, please apply here. Otherwise, feel free to send us an email with your CV attached.



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