Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: M$^2$BEV: Multi-Camera Joint 3D Detection and Segmentation with Unified
  Birds-Eye View Representation   In this paper, we propose M$^2$BEV, a unified framework that jointly performs
3D object detection and map segmentation in the Birds Eye View~(BEV) space with
multi-camera image inputs. Unlike the majority of previous works which
separately process detection and segmentation, M$^2$BEV infers both tasks with
a unified model and improves efficiency. M$^2$BEV efficiently transforms
multi-view 2D image features into the 3D BEV feature in ego-car coordinates.
Such BEV representation is important as it enables different tasks to share a
single encoder. Our framework further contains four important designs that
benefit both accuracy and efficiency: (1) An efficient BEV encoder design that
reduces the spatial dimension of a voxel feature map. (2) A dynamic box
assignment strategy that uses learning-to-match to assign ground-truth 3D boxes
with anchors. (3) A BEV centerness re-weighting that reinforces with larger
weights for more distant predictions, and (4) Large-scale 2D detection
pre-training and auxiliary supervision. We show that these designs
significantly benefit the ill-posed camera-based 3D perception tasks where
depth information is missing. M$^2$BEV is memory efficient, allowing
significantly higher resolution images as input, with faster inference speed.
Experiments on nuScenes show that M$^2$BEV achieves state-of-the-art results in
both 3D object detection and BEV segmentation, with the best single model
achieving 42.5 mAP and 57.0 mIoU in these two tasks, respectively.

16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin