KEYWORDS: Data modeling, Image analysis, Visual process modeling, Education and training, Cameras, Performance modeling, Mixtures, Ablation, Visualization, Systems modeling
A topic model is a probabilistic method for data analysis and characterization that provides insight into the topics that comprise each document in a corpus, where each topic is described by an associated word distribution. A dynamic topic model is an extension of this model that can be applied to time series data. These models have typically been applied to the text domain where the concepts of tokens and words are well defined. Applying these models to the image domain is non-obvious because the concepts of tokens and words need to hand-crafted. In this work, we apply the dynamic topic model to a sequence of images to provide insight into their dynamic nature, e.g., by helping to identify interesting locations in time that correspond to change in operating conditions We apply this model to images from the KITTI dataset and show that the model captures the evolving nature of these topics over time.
KEYWORDS: Synthetic aperture radar, 3D modeling, Education and training, 3D image processing, Data modeling, Image processing, 3D acquisition, Voxels, Machine learning, Solid modeling
An important application of deep learning classifiers is to recognize vehicles or ships in satellite images. Neural Radiance Field (NeRF) methods apply a limited number of 2D electro-optical (EO) views of an object to learn its 3D shape and view-dependent radiance properties. The resulting latent model generates novel views for training a deep learning classifier. Space-based synthetic aperture radar (SAR) sensors present a new, useful source of wide-area imagery. Because SAR phenomenology and geometry are different from EO, we construct a suitable NeRF-like approach for SAR and demonstrate generation of realistic simulated SAR imagery..Several commercial and military applications classify vehicles or ships in satellite images. In many cases, it is infeasible to acquire looks at the objects over the wide range of views and conditions needed for machine learning classifier training. Neural Radiance Fields (NeRF) and other related methods apply a limited number of 2D views of an object to learn its 3D shape and view-dependent radiance properties. One application of these techniques is to generate additional, novel views of objects for training deep learning classifiers. Current NeRF and NeRF-like methods have been demonstrated with electro-optical (EO) imagery. The emergence of space-based synthetic aperture radar (SAR) imaging sensors presents a new, useful source of wide-area imagery with day/night, all-weather commercial and military applications. Because SAR imaging phenomenology and projection geometry are different from EO, the application of NeRF-like methods to generate novel SAR images of objects for training a classifier presents new challenges. For example, unlike EO, the mono-static SAR illumination source moves with the sensor view geometry. In addition, the 2D SAR image projection is angle-range, not angle-angle. In this paper, we evaluate the salient differences between EO and SAR, and construct a processing pipeline to generate realistic synthetic SAR imagery. The synthetic SAR imagery provides additional training data, augmenting collected image data, for machine learning-based Automatic Target Recognition (ATR) algorithms. We provide examples of synthetic SAR image creation using this approach.
Object detection is a central theme for many Artificial Intelligence (AI) applications such as autonomous vehicles, surveillance etc. The algorithms providing this capability rely on training data being available in corresponding sensor mode. Having co-located data from multiple sensor modes enhances the detection confidence, but the availability of training data in desired sensor mode is not always readily available, which slows down progress. In this paper, we investigate the ability to translate images from one sensor mode to another, on a single fixed camera dataset, using conditional Generative Adversarial Network (cGAN). Specifically, images are transferred from Electro-Optical (EO) to Infra-Red (IR) images and vice-versa using cGAN models, which are generative models that learn the data distribution in a minimax game setting. To investigate the usability of such transferred images, we apply object detection algorithm on ground truth and transferred images and compare their performance. The results indicate that transferred images match closely to real images and object detection has good performance on transferred images, especially when the object size is large.
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