Alireza Ghasemi

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In this paper, we propose a novel human computation game for sentiment analysis. Our game aims at annotating sentiments of a collection of text documents and simultaneously constructing a highly discriminative lexicon of positive and negative phrases. Human computation games have been widely used in recent years to acquire human knowledge and use it to(More)
We present LCAV-31, a multi-view object recognition dataset designed specifically for benchmarking light field image analysis tasks. The principal distinctive factor of LCAV-31 compared to similar datasets is its design goals and availability of novel visual information for more accurate recognition (i.e. light field information). The dataset is composed of(More)
We propose a scale-invariant feature descriptor for representation of light-field images. The proposed descriptor can significantly improve tasks such as object recognition and tracking on images taken with recently popularized light field cameras. We test our proposed representation using various light field images of different types, both synthetic and(More)
Although many advances have been made in light-field and camera-array image processing, there is still a lack of thorough analysis of the localisation accuracy of different multi-camera systems. By considering the problem from a frame-quantisation perspective, we are able to quantify the point localisation error of circular camera configurations.(More)
—During recent years, active learning has evolved into a popular paradigm for utilizing user's feedback to improve accuracy of learning algorithms. Active learning works by selecting the most informative sample among unlabeled data and querying the label of that point from user. Many different methods such as uncertainty sampling and minimum risk sampling(More)
We propose a novel approach for detecting printed photos from natural scenes using a light-field camera. Our approach exploits the extra information captured by a light-field camera and the multiple views of scene in order to infer a compact feature vector from the variance in the distribution of the depth of the scene. We then use this feature for robust(More)
—In this paper, we investigate point localisation using multi-camera systems consisting of cameras with a finite number of pixels, under the assumption of known camera poses and error-free feature matching. We prove that, for any 2D multi-camera system and triangulation algorithm, the average localisation performance cannot asymptotically decay faster than(More)
We propose a novel camera pose estimation or perspective-n-point (PnP) algorithm, based on the idea of consistency regions and half-space intersections. Our algorithm has linear time-complexity and a squared reconstruction error that decreases at least quadratically, as the number of feature point correspondences increase. Inspired by ideas from(More)