Autoregressive Uncertainty Modeling for 3D Bounding Box Prediction
YuXuan Liu, Nikhil Mishra, Maximilian Sieb, Yide Shentu, Pieter Abbeel, and Xi Chen
Covariant.ai, UC Berkeley
Abstract: 3D bounding boxes are a widespread intermediate representation in many computer vision applications. However, predicting them is a challenging task, largely due to partial observability, which motivates the need for a strong sense of uncertainty. While many recent methods have explored better architectures for consuming sparse and unstructured point cloud data, we hypothesize that there is room for improvement in the modeling of the output distribution and explore how this can be achieved using an autoregressive prediction head. Additionally, we release a simulated dataset, COB-3D, which highlights new types of ambiguity that arise in real-world robotics applications, where 3D bounding box prediction has largely been underexplored. We propose methods for leveraging our autoregressive model to make high confidence predictions and meaningful uncertainty measures, achieving strong results on SUN-RGBD, Scannet, KITTI, and our new dataset.
We autoregressively sample dimensions, center, and rotations, each step conditioned on the previous one. We can express uncertainty through samples, such as the rotational symmetry of the bottle, whereas pointwise models could only make a single prediction.
For indoor 3D Object Detection, we use FCAF3D as a base model with an autoregressive head for bounding box prediction. For 3D Bounding Box Estimation we take object-centric features from a 2D object detector and pass them into a 2D CNN for autoregressive bounding box prediction.
a) In this scene from a real-world robotics application, how tall is the object highlighted in red? b) A pointwise model could output only one box prediction with no notion of uncertainty c)-e) Predictions from our confidence box method. Notice that the predicted box expands in the direction of uncertainty as we increase the confidence requirement. f) Our dimension conditioning method can leverage additional information to make more accurate predictions.