Shadows and Light. Ernie Gehr Exhibitions at the Museum of Modern Art

This thesis examines exhibitions and media installations of Ernie Gehr’s work at The Museum of Modern Art (MoMA), beginning with the pivotal 1970 show Information, which presented four films by Gehr. Wait (1968), Transparency (1969), Reverberation (1969), and History (1970) were screened alongside work by other avant-garde filmmakers and video artists in a circular viewing booth in the gallery space, in a show featuring works now considered masterpieces of conceptual art. It also considers the two site-specific video works, MoMA on Wheels (2002) and Navigation (2002), which Gehr created for the lobby space at MoMA QNS, the temporary home for the museum during construction for a major expansion project. Finally it explores Gehr’s two major solo exhibitions, Panoramas of the Moving Image: Mechanical Slides and Dissolving Views from Nineteenth-Century Magic Lantern Shows from 2007, and Carnival of Shadows from 2015. Descriptive analysis of each film or installation, inflected with methodologic devices of film history, art history, and philosophy, grounds discussion of the works within the surrounding context of the Museum

To 3D or Not 3D: Choosing a Photogrammetry Workflow for Cultural Heritage Groups

The 3D reconstruction of real-world heritage objects using either a laser scanner or 3D modelling software is typically expensive and requires a high level of expertise. Image-based 3D modelling software, on the other hand, offers a cheaper alternative, which can handle this task with relative ease. There also exists free and open source (FOSS) software, with the potential to deliver quality data for heritage documentation purposes. However, contemporary academic discourse seldom presents survey-based feature lists or a critical inspection of potential production pipelines, nor typically provides direction and guidance for non-experts who are interested in learning, developing and sharing 3D content on a restricted budget. To address the above issues, a set of FOSS were studied based on their offered features, workflow, 3D processing time and accuracy. Two datasets have been used to compare and evaluate the FOSS applications based on the point clouds they produced. The average deviation to ground truth data produced by a commercial software application (Metashape, formerly called PhotoScan) was used and measured with CloudCompare software. 3D reconstructions generated from FOSS produce promising results, with significant accuracy, and are easy to use. We believe this investigation will help non-expert users to understand the photogrammetry and select the most suitable software for producing image-based 3D models at low cost for visualisation and presentation purposes

Parallax-Tolerant Image Stitching

Parallax handling is a challenging task for image stitch-ing. This paper presents a local stitching method to handle parallax based on the observation that input images do not need to be perfectly aligned over the whole overlapping re-gion for stitching. Instead, they only need to be aligned in a way that there exists a local region where they can be seam-lessly blended together. We adopt a hybrid alignment model that combines homography and content-preserving warp-ing to provide flexibility for handling parallax and avoiding objectionable local distortion. We then develop an efficient randomized algorithm to search for a homography, which, combined with content-preserving warping, allows for op-timal stitching. We predict how well a homography enables plausible stitching by finding a plausible seam and using the seam cost as the quality metric. We develop a seam finding method that estimates a plausible seam from only roughly aligned images by considering both geometric alignment and image content. We then pre-align input images using the optimal homography and further use content-preserving warping to locally refine the alignment. We finally compose aligned images together using a standard seam-cutting al-gorithm and a multi-band blending algorithm. Our exper-iments show that our method can effectively stitch images with large parallax that are difficult for existing methods. 1