Large Scale SfM with the Distributed Camera Model

We introduce the distributed camera model, a novel model for Structure-from-Motion (SfM). This model describes image observations in terms of light rays with ray origins and directions rather than pixels. As such, the proposed model is capable of describing a single camera or multiple cameras simultaneously as the collection of all light rays observed. We show how the distributed camera model is a generalization of the standard camera model and describe a general formulation and solution to the absolute camera pose problem that works for standard or distributed cameras. The proposed method computes a solution that is up to 8 times more efficient and robust to rotation singularities in comparison with gDLS. Finally, this method is used in an novel large-scale incremental SfM pipeline where distributed cameras are accurately and robustly merged together. This pipeline is a direct generalization of traditional incremental SfM; however, instead of incrementally adding one camera at a time to grow the reconstruction the reconstruction is grown by adding a distributed camera. Our pipeline produces highly accurate reconstructions efficiently by avoiding the need for many bundle adjustment iterations and is capable of computing a 3D model of Rome from over 15,000 images in just 22 minutes.Comment: Published at 2016 3DV Conferenc

GraphMatch: Efficient Large-Scale Graph Construction for Structure from Motion

We present GraphMatch, an approximate yet efficient method for building the matching graph for large-scale structure-from-motion (SfM) pipelines. Unlike modern SfM pipelines that use vocabulary (Voc.) trees to quickly build the matching graph and avoid a costly brute-force search of matching image pairs, GraphMatch does not require an expensive offline pre-processing phase to construct a Voc. tree. Instead, GraphMatch leverages two priors that can predict which image pairs are likely to match, thereby making the matching process for SfM much more efficient. The first is a score computed from the distance between the Fisher vectors of any two images. The second prior is based on the graph distance between vertices in the underlying matching graph. GraphMatch combines these two priors into an iterative "sample-and-propagate" scheme similar to the PatchMatch algorithm. Its sampling stage uses Fisher similarity priors to guide the search for matching image pairs, while its propagation stage explores neighbors of matched pairs to find new ones with a high image similarity score. Our experiments show that GraphMatch finds the most image pairs as compared to competing, approximate methods while at the same time being the most efficient.Comment: Published at IEEE 3DV 201

The use of everyday technologies to enhance wellbeing and enjoyment for people living with dementia: A systematic literature review and narrative synthesis grounded in qualitative data

BackgroundEveryday technologies, such as laptops and tablets, are often used for enjoyment, pleasure, leisure and social participation. Despite this, whilst considerable research has investigated exploring people’s experiences of using assistive technologies, it is not clear how everyday technologies are experienced by individuals living with dementia. The aims of this review were to explore the experiences and views of people living with dementia and carers about using everyday technology to enhance their well-being and enjoyment, social engagement, participation and leisure as well as understand their views about the usability of everyday technology in dementia.MethodsA systematic search of the literature was conducted using the electronic databases: PsycINFO, PsycARTICLES, CINAHL Complete and EThOS. Five qualitative studies and five mixed-method studies were included and synthesised using a narrative approach. The methodological quality of the studies was assessed using the National Institute for Health and Care Excellence Qualitative Quality Appraisal, which uncovered key variation in the quality of the included, synthesised studies.FindingsThe review suggests that everyday technologies can help support well-being, particularly when technology is used in a group setting and when individuals received the right amount of support to help engage in the technology. Four major themes relating to experiences and views were derived from the findings of the 10 included studies: ‘Technology use maintaining a sense of identity’, ‘Assumptions held by the self and others’, ‘The importance of others’ and ‘The usability of technology influencing effective engagement’.ConclusionsOverall, everyday technologies appear to have a positive impact on different aspects of the well-being of people living with dementia. Clinical implications of these findings include supporting opportunities for people living with dementia to use everyday technology for enjoyment and making these technologies more widely available and accessible

Modeling and Calibrating the Distributed Camera

Structure-from-Motion (SfM) is a powerful tool for computing 3D reconstructions from images of a scene and has wide applications in computer vision, scene recognition, and augmented and virtual reality. Standard SfM pipelines make strict assumptions about the capturing devices in order to simplify the process for estimating camera geometry and 3D structure. Specifically, most methods require monocular cameras with known focal length calibration. When considering large-scale SfM from internet photo collections, EXIF calibrations cannot be used reliably. Further, the requirement of single camera systems limits the scalability of SfM. This thesis proposes to remove these constraints by instead considering the collection of cameras as a distributed camera that encapsulates the image and geometric information of all cameras simultaneously. First, I provide full generalizations to the relative camera pose and absolute camera pose problems. These generalizations are more expressive and extend the traditional single-camera problems to distributed cameras, forming the basis for a novel hierarchical SfM pipeline that exhibits state-of-the-art performance on large-scale datasets. Second, I describe two efficient methods for estimating camera focal lengths for the distributed camera when calibration is not available. Finally, I show how removing these constraints enables a simpler, more scalable SfM pipeline that is capable of handling uncalibrated cameras at scale

Fuller Farmstead: Reuse & Rehabilitation Feasibility Report

A new atrium has been proposed to accommodate the needs of the Barnstable Land Trusts proposed programs. The atrium would provide a well defined, ADA accessible entrance to the building. Design of the new atrium would apply to the Secretary of the Interior’s Standards for new exterior additions to historic properties. It is recommended that the atrium be constructed on the west façade, after the demolition of 2/3 of the southwest ells

The realities of storing carbon dioxide - A response to CO2 storage capacity issues raised by Ehlig-Economides & Economides

In a recent publication, Ehlig-Economides & Economides (2010) have sought to demonstrate that carbon dioxide capture and storage (CCS) is not technically or economically feasible, based on a supposed lack of underground storage capacity. We consider this to be a serious misrepresentation of the scientific, engineering and operational facts surrounding CCS. Ehlig-Economides & Economides raise a number of storage related issues: reservoir boundaries, capacity, pressure management, storage integrity, dissolution and storage in depleted reservoirs. We take each one in turn, highlighting specific errors in the paper but also drawing attention to more general background issues. Finally, we discuss in more detail some inconsistencies in the paper surrounding the reservoir engineering calculations