Semantic Segmentation using convolutional neural networks is a trending technique in scene understanding. As these techniques are data-intensive, several devices struggle to store and process even a small batch of images at a time. Also, as the volume of training datasets required by the training algorithms is very high, it might be wise to store these datasets in their compressed form. Not only this, in order to correspond the limited bandwidth of the transmission network the images could be compressed before sending to the destination. Joint Photography Expert Group (JPEG) is a famous technique for image compression. However, JPEG introduces several unwanted artifacts in the images after compression. In this paper, we explore the effect of JPEG compression on the performance of several deep-learning-based semantic segmentation techniques for both the synthetic and real-world dataset at various compression levels. For some established architectures trained with compressed synthetic and real-world dataset, we noticed the equivalent (and sometimes better) performances compared to uncompressed dataset with substantial amount of storage space reduced. We also analyze the effect of combining original dataset with the compressed dataset with different JPEG quality levels and witnessed a performance improvement over the baseline. Our evaluation and analysis indicates that the segmentation network trained on compressed dataset could be a better option in terms of performance. We also illustrate that the JPEG compression acts as a data augmentation technique improving the performance of semantic segmentation algorithms.
For autonomous vehicles 3D, rotating LiDAR sensors are often critically important towards the vehicle’s ability to sense its environment. Generally, these sensors scan their environment, using multiple laser beams to gather information about the range and the intensity of the reflection from an object. LiDAR capabilities have evolved such that some autonomous systems employ multiple rotating LiDARs to gather greater amounts of data regarding the vehicle’s surroundings. For these multi–LiDAR systems, the placement of the sensors determine the density of the combined point cloud. We perform preliminary research regarding the optimal LiDAR placement strategy on an off–road, autonomous vehicle known as the Halo project. We use the Mississippi State University Autonomous Vehicle Simulator (MAVS) to generate large amounts of labeled LiDAR data that can be used to train and evaluate a neural network used to process LiDAR data in the vehicle. The trained networks are evaluated and their performance metrics are then used to generalize the performance of the sensor pose. Data generation, training, and evaluation, was performed iteratively to perform a parametric analysis of the effectiveness of various LiDAR poses in the Multi–LiDAR system. We also, describe and evaluate intrinsic and extrinsic calibration methods that are applied in the multi–LiDAR system. In conclusion we found that our simulations are an effective way to evaluate the efficacy of various LiDAR placements based on the performance of the neural network used to process that data and the density of the point cloud in areas of interest.