Video Scene Parsing with Predictive Feature Learning : — Supplementary Material —

In this supplementary material, we provide more implementation details including the architectures and training settings of baseline models and PEARL. We also present the experimental results and analysis of PEARL on Camvid dataset, as well as more qualitative evaluations of PEARL. 1. Implementation Details Since the class distribution is extremely unbalanced in video scene parsing, we increase the weight of rare classes during training, similar to [3, 6, 15]. In particular, we adopt the re-weighting strategy in [15]. The weight for the class y is set as ωy = 2 ⌈log 10(η/fy)⌉ where fy is the frequency of class y and η is a dataset-dependent scalar which is defined using the 85%/15% frequent/rare classes rule. All of our experiments are carried out on NVIDIA Titan X and Tesla M40 GPUs using Caffe library. 1.1. Network Architectures To demonstrate that PEARL can be applied with advanced deep architectures, we implement PEARL and baseline models using two state-of-the-art deep architectures: i.e. VGG16 and Res101 and compare their performance. For fair comparison, both the frame parsing network and the predictive learning network in PEARL share the same architecture as baseline models except for the input/output layers in the predictive learning network (which takes multiple frames as inputs and outputs RGB frames instead of parsing maps). In the following, we first introduce the architecture details of baseline models (i.e., the following VGG16baseline and Res101-baseline) and then the differences between PEARL and these baselines. • VGG16-baseline The VGG16-baseline is built upon DeepLab [2] with two modifications. First, to further enhance model’s ability for video scene parsing, we add Feature map Global pooling Up-sampling 1 × 1 c o n v , 1 0 2 4 1024-d Output features Concatenation Global Contexture Module Figure 1: Architecture of the global contexture module which is applied to encode the image global context information as suggested in ParseNet [12]. The output feature map of fc7/conv5 3 layer in VGG16/Res101 architectures in our experiments is passed through such global contextual module to produce a global context augmented feature map by global average pooling, up-sampling and concatenation with fc7/conv3 3 output feature map. A 1×1 convolutional layer is then applied to the concatenated feature map to produce the output features with 1,024 channels. three deconvolutional layers (each followed by ReLU) to up-sample the fc7 output features of DeepLab. The three deconvolutional layers consist of 4 × 4 convolutional kernels with striding of size 2 and padding of size 1. The number of kernels are 256, 128 and 64 respectively. Besides, following ParseNet [12], we use the global contexture module for fc7 features to enhance the model’s capability of capturing global context information. As shown in Figure 1, the global contexture module transforms the input feature map to a 1024-channel feature map. In experiments, we find such a module improves the parsing performance of the baseline model as it enlarges the model’s receptive field size and utilizes the global information to distinguish local confusing pixels. • Res101-baseline The architecture of our Res101baseline is illustrated in Figure 2. It is modified from the original Res101 [5] by adapting it to a fully convolutional network, following [14]. Specifically, we replace the average pooling layer and the 1,000-way classification layer with a fully convolutional layer (denoted as conv5 3cls in Figure 2) to produce dense parsing maps.