Sensor-Assisted Video Mosaicing for Seafloor Mapping

This paper discusses a proposed processing technique for combining video imagery with auxiliary sensor information. The latter greatly simplifies image processing by reducing complexity of the transformation model. The mosaics produced by this technique are adequate for many applications, in particular habitat mapping. The algorithm is demonstrated through simulations and hardware configuration is described

Seafloor Video Mapping: Modeling, Algorithms, Apparatus

This paper discusses a technique used for construction of high-resolution image mosaic from a videosequence and the synchronously logged camera attitude information. It allows one to infer geometric characteristics of the imaged terrain and hence improve the mosaic quality and reduce the computational burden. The technique is demonstrated using numerical modeling and is applied to videodata collected on Rainsford Island, Mass. Calculation of the transformation relating consecutive image frames is an essential operation affecting reliability of the whole mosaicing process. Improvements to the algorithm are suggested, which significantly decrease the possibility of convergence to an inappropriate solution

Improvement of Image Alignment Using Camera Attitude Information

We discuss a proposed technique for incorporation of information from a variety of sensors in a video imagery processing pipeline. The auxiliary information allows one to simplify computations, effectively reducing the number of independent parameters in the transformation model. The mosaics produced by this technique are adequate for many applications, in particular habitat mapping. The algorithm, demonstrated through simulations and hardware configuration, is described in detai

Underwater Video Survey: Planning and Data Processing

The importance of underwater video surveys as an exploration tool has been steadily increasing over recent years [1]. Better photographic equipment, more effective sources of illumination, and improved processing techniques - all make video surveying a reliable tool for seafloor habitat mapping, sediment boundary delineation and groundtruthing, mapping and documentation of forensic and archaeological sites. There is a change in attitude towards video surveying that affects the way the data is collected, and hence its quality. Earlier video data processing algorithms had to cope with whatever was recorded (often simultaneously with acquisition of other data, considered to be more important). Now we have a chance to plan ahead and organize a survey in a way most suitable for the processing. The goal of this paper is to review available processing techniques and to discuss preferable survey patterns, associated errors and processing stability

Seafloor Segmentation Based on Bathymetric Measurements from Multibeam Echosounders Data

Bathymetric data depicts the geomorphology of the seabottom and allows characterization of spatial distributions of apparent benthic habitats. The variability of seafloor topography can be defined as a texture. This prompts for the application of well developed image processing techniques for automatic delineation of regions with clucially different physiographic characteristics. In the present paper histograms of biologically motivated invariant image attributes are used for characterization of local geomorphological feahires. This technique can be naturally applied in a range of spatial scales. Local feature vectors are then submitted to a procedure which divides the set into a number of clusters each representing a distinct type of the seafloor. Prior knowledge about benthic habitat locations allows the use of supervised classification, by training a Suppolt Vector Machine on a chosen data set, and then applying the developed model to a full set. The classification method is shown to perform well on the multibeam echosounder (MBES) data from Piscataqua River, New Hampshire, USA

Sensor-assisted Video Mapping of the Seafloor

In recent years video surveys have become an increasingly important ground-truthing of acousticseafloor characterization and benthic habitat mapping studies. However, the ground-truthing and detailed characterization provided by video are still typically done using sparse sample imagery supplemented by physical samples. Combining single video frames in a seamless mosaic can provide a tool by which imagery has significant areal coverage, while at the same time showing small fauna and biological features at mm resolution. The generation of such a mosaic is a challenging task due to height variations of the imaged terrain and decimeter scale knowledge of camera position. This paper discusses the current role of underwater video survey, and the potential for generating consistent, quantitative image maps using video data, accompanied by data that can be measured by auxiliary sensors with sufficient accuracy, such as camera tilt and heading, and their use in automated mosaicking techniques. The camera attitude data also provide the necessary information to support the development of a video collage. The collage provides a quick look at the large spatial scale features in a scene and can be used to pinpoint regions that are likely to yield useful information when rendered into high-resolution mosaics. It is proposed that high quality mosaics can be produced using consumer-grade cameras and low-cost sensors, thereby allowing for the economical scientific video surveys. A case study is presented with the results from benthic habitat mapping and the ground-truthing ofseafloor acoustic data using both real underwater imagery and simulations. A computer modeling of the process of video data acquisition (in particular on a non-flat terrain) allows for a better understanding of the main sources of error in mosaic generation and for the choice of near-optimal processing strategies. Various spatial patterns of video survey coverage are compared and it is shown that some patterns have certain advantages in the sense of accumulated error and overall mosaic accuracy

Climate Change Adaptation in Mediterranean Cities: An Introduction to the Special Issue

Given the highly developed nature of Mediterranean regions and their importance in global trade and migration, it is crucial to develop comprehensive solutions for climate change. The widespread societal impacts of climate change add urgency towards transdisciplinary and transnational solutions for climate change adaptation. We represent the Mediterranean Climate Change Consortium (MC-4), an international network of scholars, policy makers, and practitioners working towards climate change adaptation in cities with Mediterranean climates. Our proposition is that areas with similar, Mediterranean, climates will have more climate adaptation lessons to share with each other than areas with distinctly different climates. As a step towards this, we present this special issue, which is a collection of articles and practitioner notes focused on climate change adaptation in Mediterranean climate cities. While this issue has a special focus on southern California, we hope these articles serve as a springboard for the discussion of adaptation lessons from other Mediterranean areas. We look forward to highlighting these regions in subsequent issues. We would like to invite other Mediterranean climate change adaptation scholars and professionals to join us in sharing their research and case studies to be collected in this volume