Visual Simultaneous Localization and Mapping (vSLAM) system is widely used by autonomous mobile robots. Most vSLAM systems use cameras to analyze surrounding environment and to build maps for autonomous navigation. For a robot to perform intelligent tasks, the built map should be accurate. Landmark features are crucial elements for mapping and path planning. In the vSLAM literature, loop closure detection is a very important process for enhancing the robustness of the vSLAM algorithms. The most widely used algorithms for loop closure detection use a single descriptor. However, the performance of the single descriptors appears to worsen as the map keeps growing. One possible solution to this problem is to use multiple descriptors and combine them as in Naive and linear combinations. These approaches, however, have weaknesses in recognizing the correct locations due to overfitting and highbias, which hinder the generalization performance. This paper proposes the usage of ensemble learning to combine the predictions of multiple Bayesian filter models which make more accurate prediction than individual models. The proposed approach is validated on three public datasets; namely, Lip6 Indoor, Lip6 Outdoor and City Centre. The results show that the proposed ensemble algorithm significantly outperforms the single approaches with a recall of 80%, 97% and 87%, with 100% precision on the three datasets, and outperforms the Naive approach and the existing loop closure detection algorithms.
The false positive (FP) is an over-segment result where the noncancerous pixel is segmented as a cancer pixel. The FP rate is considered a challenge in localising masses in mammogram images. Hence, in this article, a rejection model is proposed by using a supervised learning method in mass classification such as support vector machine (SVM). The goal of the rejection model which is based on SVM is the reduction of FP rate in segmenting mammogram through the Chan-Vese method, which is initialised by the marker controller watershed (MCWS) algorithm. The MCWS algorithm is utilised for segmentation of a mammogram image. The segmentation is subsequently refined through the Chan-Vese method, followed by the development of the proposed SVM rejection model with different window size as well as its application in eliminating incorrect segmented nodules. The dataset comprised of 57 nodules and 113 non-nodules and the study successfully proved the effectiveness of the SVM rejection model to decrease the FP rate.
The Gleason grading system assists in evaluating the prognosis of men with prostate cancer. Cancers with a higher score are more aggressive and have a worse prognosis. The pathologists observe the tissue components (e.g. lumen, nuclei) of the histopathological image to grade it. The differentiation between Grade 3 and Grade 4 is the most challenging, and receives the most consideration from scholars. However, since the grading is subjective and time-consuming, a reliable computer-aided prostate cancer diagnosing techniques are in high demand. This study proposed an ensemble computer-added system (CAD) consisting of two single classifiers: a) a specialist, trained specifically for texture features of the lumen and the other for nuclei tissue component; b) a fusion method to aggregate the decision of the single classifiers. Experimental results show promising results that the proposed ensemble system (area under the ROC curve (Az) of 88.9% for Grade 3 versus Grad 4 classification task) impressively outperforms the single classifier of nuclei (Az=87.7) and lumen (Az=86.6).