Unsupervised spectral sub-feature learning for hyperspectral image classification

Spectral pixel classification is one of the principal techniques used in hyperspectral image (HSI) analysis. In this article, we propose an unsupervised feature learning method for classification of hyperspectral images. The proposed method learns a dictionary of sub-feature basis representations from the spectral domain, which allows effective use of the correlated spectral data. The learned dictionary is then used in encoding convolutional samples from the hyperspectral input pixels to an expanded but sparse feature space. Expanded hyperspectral feature representations enable linear separation between object classes present in an image. To evaluate the proposed method, we performed experiments on several commonly used HSI data sets acquired at different locations and by different sensors. Our experimental results show that the proposed method outperforms other pixel-wise classification methods that make use of unsupervised feature extraction approaches. Additionally, even though our approach does not use any prior knowledge, or labelled training data to learn features, it yields either advantageous, or comparable, results in terms of classification accuracy with respect to recent semi-supervised methods

Image-based road type classification

The ability to automatically determine the road type from sensor data is of great significance for automatic annotation of routes and autonomous navigation of robots and vehicles. In this paper, we present a novel algorithm for content-based road type classification from images. The proposed method learns discriminative features from training data in an unsupervised manner, thus not requiring domain-specific feature engineering. This is an advantage over related road surface classification algorithms which are only able to make a distinction between pre-specified uniform terrains. In order to evaluate the proposed approach, we have constructed a challenging road image dataset of 20,000 samples from real-world road images in the paved and unpaved road classes. Experimental results on this dataset show that the proposed algorithm can achieve state-of-the-art performance in road type classification

Visitor-art interaction by motion path detection

This paper describes a method for video-based motion path detection which is applied in the creation of an interactive artwork. The proposed algorithm, based on the Hough transform, detects parametric motion trajectories in real-time (10 fps). In order to detect people's motion under non-static background object occlusion we have also developed a video segmentation technique. The proposed interaction system adopts top-down camera view to extract spatiotemporal motion trajectories and discern predefined patterns of movement thus enabling the creation of new artistic choreographies. We present test results that illustrate the effectiveness of our method and discuss the practical applicability of our approach in other domains

Characterizing the response of charge-couple device digital color cameras

The advance and rapid development of electronic imaging technology has lead the way to production of imaging sensors capable of acquiring good quality digital images with a high resolution. At the same time the cost and size of imaging devices have reduced. This has incited an increasing research interest for techniques that use images obtained by multiple camera arrays. The use of multi-camera arrays is attractive because it allows capturing multi-view images of dynamic scenes, enabling the creation of novel computer vision and computer graphics applications, as well as next generation video and television systems. There are additional challenges when using a multi-camera array, however. Due to inconsistencies in the fabrication process of imaging sensors and filters, multi-camera arrays exhibit inter-camera color response variations. In this work we characterize and compare the response of two digital color cameras, which have a light sensor based on the charge-coupled device (CCD) array architecture. The results of the response characterization process can be used to model the cameras’ responses, which is an important step when constructing a multi-camera array system