911 research outputs found
PWC-Net: CNNs for Optical Flow Using Pyramid, Warping, and Cost Volume
We present a compact but effective CNN model for optical flow, called
PWC-Net. PWC-Net has been designed according to simple and well-established
principles: pyramidal processing, warping, and the use of a cost volume. Cast
in a learnable feature pyramid, PWC-Net uses the cur- rent optical flow
estimate to warp the CNN features of the second image. It then uses the warped
features and features of the first image to construct a cost volume, which is
processed by a CNN to estimate the optical flow. PWC-Net is 17 times smaller in
size and easier to train than the recent FlowNet2 model. Moreover, it
outperforms all published optical flow methods on the MPI Sintel final pass and
KITTI 2015 benchmarks, running at about 35 fps on Sintel resolution (1024x436)
images. Our models are available on https://github.com/NVlabs/PWC-Net.Comment: CVPR 2018 camera ready version (with github link to Caffe and PyTorch
code
Learning Fully Dense Neural Networks for Image Semantic Segmentation
Semantic segmentation is pixel-wise classification which retains critical
spatial information. The "feature map reuse" has been commonly adopted in CNN
based approaches to take advantage of feature maps in the early layers for the
later spatial reconstruction. Along this direction, we go a step further by
proposing a fully dense neural network with an encoder-decoder structure that
we abbreviate as FDNet. For each stage in the decoder module, feature maps of
all the previous blocks are adaptively aggregated to feed-forward as input. On
the one hand, it reconstructs the spatial boundaries accurately. On the other
hand, it learns more efficiently with the more efficient gradient
backpropagation. In addition, we propose the boundary-aware loss function to
focus more attention on the pixels near the boundary, which boosts the "hard
examples" labeling. We have demonstrated the best performance of the FDNet on
the two benchmark datasets: PASCAL VOC 2012, NYUDv2 over previous works when
not considering training on other datasets
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