Channel invariant online visibility enhancement for visual SLAM in a turbid environment

This paper presents a real‐time and channel‐invariant visibility enhancement algorithm using a hybrid image enhancement approach. The proposed method is initially motivated by an underwater visual simultaneous localization and mapping (SLAM) failure in a turbid medium. The environments studied contain various particles and are dominated by a different image degradation model. Targeting image enhancement for degraded images but not being limited to it, the proposed method provides a highly effective solution for both color and gray images with substantial improvement in the process time compared to conventional methods. The proposed method introduces a hybrid scheme of two image enhancement modules: a model‐based (extensive) enhancement and a model‐free (immediate) enhancement. The proposed method is validated by using simulated synthetic color images and real‐world color and grayscale underwater images. Real‐world validation is performed in various environments such as hazy indoor, smoky indoor, and underwater. Using the ground truth trajectory or clear images acquired from the same area but without turbidity, we evaluate the proposed visibility enhancement and camera registration improvement for a feature based (ORB‐SLAM2), a direct (LSD‐SLAM), and a visual underwater SLAM application.     

Graphene‐Mimicking 2D Porous Co3O4 Nanofoils for Lithium Battery Applications

2D nanoscale oxides have attracted a large amount of research interest due to their unique properties. Here, a facile synthetic approach to prepare graphene‐mimicking, porous 2D Co₃O₄ nanofoils using graphene oxide (GO) as a sacrificial template is reported. The thermal instability of graphene, as well as the catalytic ability of Co₃O₄ particles to degrade carbon backbones, allow the fabrication of porous 2D Co₃O₄ nanofoils without the loss of the 2D nature of GO. Based on these results, a graphene mimicking as a route for large‐area 2D transition metal oxides for applications in electrochemical energy storage devices is proposed. As a proof of concept, it is demonstrated that graphene‐like, porous 2D Co₃O₄ nanofoils exhibit a high reversible capacity (1279.2 mAh g^?1), even after 50 cycles. This capacity is far beyond the theoretical capacity of Co₃O₄ based on the conversion mechanism from Co₃O₄ to Li₂O and metallic Co.     

Concentric Circle‐Based Image Signature for Near‐Duplicate Detection in Large Databases

Many applications dealing with image management need a technique for removing duplicate images or for grouping related (near‐duplicate) images in a database. This paper proposes a concentric circle‐based image signature which makes it possible to detect near‐duplicates rapidly and accurately. An image is partitioned by radius and angle levels from the center of the image. Feature values are calculated using the average or variation between the partitioned sub‐regions. The feature values distributed in sequence are formed into an image signature by hash generation. The hashing facilitates storage space reduction and fast matching. The performance was evaluated through discriminability and robustness tests. Using these tests, the particularity among the different images and the invariability among the modified images are verified, respectively. In addition, we also measured the discriminability and robustness by the distribution analysis of the hashed bits. The proposed method is robust to various modifications, as shown by its average detection rate of 98.99%. The experimental results showed that the proposed method is suitable for near‐duplicate detection in large databases.     

The development of a mobile money service: an exploratory actor-network study

Mobile money has received ample academic and practitioner attention as a means to improve access to financial services in developing countries. However, there is a paucity of empirical studies examining mobile money development from a socio-technical stance. Based on an exploratory cross-sectional field study conducted at three sites in the Upper East region of Ghana, this paper attempts to understand the dynamics of the development and diffusion of a mobile money service from an actor-network theory (ANT) perspective. Data from semi-structured interviews with the principal stakeholders (supplemented by documentary evidence) were analyzed using grounded theory coding techniques and the emergent themes interpreted through the lens of the “moments of translation” (Callon, M. (1999). Some elements of a sociology of translation: Domestication of the scallops and the fishermen of St Brieuc Bay. In M. Biagioli (Ed.), The science studies reader (pp. 67–83). London: Routledge) framework of ANT. The study found that a mobile network operator has built a nascent network of composite social and material stakeholders to offer mobile money services despite significant challenges. Although the actor-network is still evolving and mobile money has yet to reach critical mass, there is evidence of growing uptake. This paper highlights the value of ANT as a lens for exploring the diffusion of innovations in information and communication technology for development (ICT4D) research.     

Automatic wall slant angle map generation using 3D point clouds

Recently, quantitative and repetitive inspections of the old urban area were conducted because many structures exceed their designed lifetime. The health of a building can be validated from the condition of the outer wall, while the slant angle of the wall widely serves as an indicator of urban regeneration projects. Mostly, the inspector directly measures the inclination of the wall or partially uses 3D point measurements using a static light detection and ranging (LiDAR). These approaches are costly, time-consuming, and only limited space can be measured. Therefore, we propose a mobile mapping system and automatic slant map generation algorithm, configured to capture urban environments online. Additionally, we use the LiDAR-inertial mapping algorithm to construct raw point clouds with gravity information. The proposed method extracts walls from raw point clouds and measures the slant angle of walls accurately. The generated slant angle map is evaluated in indoor and outdoor environments, and the accuracy is compared with real tiltmeter measurements.