HAPNet: hierarchically aggregated pyramid network for real-time stereo matching

©Recovering the 3D shape of the surgical site is crucial for multiple computer-assisted interventions. Stereo endoscopes can be used to compute 3D depth but computational stereo is a challenging, non-convex and inherently discontinuous optimisation problem. In this paper, we propose a deep learning architecture which avoids the explicit construction of a cost volume of similarity which is one of the most computationally costly blocks of stereo algorithms. This makes training our network significantly more efficient and avoids the needs for large memory allocation. Our method performs well, especially around regions comprising multiple discontinuities around surgical instrumentation or around complex small structures and instruments. The method compares well to the state-of-the-art techniques while taking a different methodological angle to computational stereo problem in surgical video

SERV-CT: A disparity dataset from cone-beam CT for validation of endoscopic 3D reconstruction

In computer vision, reference datasets from simulation and real outdoor scenes have been highly successful in promoting algorithmic development in stereo reconstruction. Endoscopic stereo reconstruction for surgical scenes gives rise to specific problems, including the lack of clear corner features, highly specular surface properties and the presence of blood and smoke. These issues present difficulties for both stereo reconstruction itself and also for standardised dataset production. Previous datasets have been produced using computed tomography (CT) or structured light reconstruction on phantom or ex vivo models. We present a stereo-endoscopic reconstruction validation dataset based on cone-beam CT (SERV-CT). Two ex vivo small porcine full torso cadavers were placed within the view of the endoscope with both the endoscope and target anatomy visible in the CT scan. Subsequent orientation of the endoscope was manually aligned to match the stereoscopic view and benchmark disparities, depths and occlusions are calculated. The requirement of a CT scan limited the number of stereo pairs to 8 from each ex vivo sample. For the second sample an RGB surface was acquired to aid alignment of smooth, featureless surfaces. Repeated manual alignments showed an RMS disparity accuracy of around 2 pixels and a depth accuracy of about 2 mm. A simplified reference dataset is provided consisting of endoscope image pairs with corresponding calibration, disparities, depths and occlusions covering the majority of the endoscopic image and a range of tissue types, including smooth specular surfaces, as well as significant variation of depth. We assessed the performance of various stereo algorithms from online available repositories. There is a significant variation between algorithms, highlighting some of the challenges of surgical endoscopic images. The SERV-CT dataset provides an easy to use stereoscopic validation for surgical applications with smooth reference disparities and depths covering the majority of the endoscopic image. This complements existing resources well and we hope will aid the development of surgical endoscopic anatomical reconstruction algorithms

Hot Dust-Obscured Galaxies with Excess Blue Light

Hot dust-obscured galaxies (Hot DOGs) are among the most luminous galaxies in the universe. Powered by highly obscured, possibly Compton-thick, active galactic nuclei (AGNs), Hot DOGs are characterized by spectral energy distributions that are very red in the mid-infrared yet dominated by the host galaxy stellar emission in the UV and optical. An earlier study identified a subsample of Hot DOGs with significantly enhanced UV emission. One target, W0204–0506, was studied in detail and, based on Chandra observations, it was concluded that the enhanced emission was most likely due to either extreme unobscured star formation (star formation rate > 1000 M_⊙ yr⁻¹) or to light from the highly obscured AGN scattered by gas or dust into our line of sight. Here, we present a follow-up study of W0204–0506 as well as two more Hot DOGs with excess UV emission. For the two new objects we obtained Chandra/ACIS-S observations, and for all three targets we obtained Hubble Space Telescope/WFC3 F555W and F160W imaging. The analysis of these observations, combined with multiwavelength photometry and UV/optical spectroscopy suggests that UV emission is most likely dominated by light from the central highly obscured, hyperluminous AGN that has been scattered into our line of sight, by either gas or dust. We cannot decisively rule out, however, that star formation or a second AGN in the system may significantly contribute to the UV excess of these targets

Glocal participatory system for the recording, documentation and promotion of cultural heritage: A greek case-study

The recording, documentation and promotion of local cultural heritage has been the subject of significant research from scientists from various fields such as architecture, anthropology, history, folklore, ethnomusicology, and museology. This paper argues that digital technologies could have a catalytic role concerning the operational part of a holistic–interdisciplinary approach to the maintenance of cultural heritage. Simultaneous and bidirectional recording, documentation and promotion of human histories, material elements of space, personal and collective memories, music, dance, singing and other performances, customs, traditions etc. has the effect of improving the understanding of each place and, therefore, contributing to the establishment of sustainable living conditions and environmental balance. At the same time, it facilitates the process of presenting the place’s local identity as well as its tangible and intangible cultural heritage. The paper proposes the design, the creation and the pilot operation of a glocal hybrid (physical and digital) participatory system for monitoring cultural heritage, which consists of (a) spatial recording and projection constructions (open micro-labs); (b) research and documentation centers; and (c) digital databases and mobile applications for interconnection and diffusion of digital content. The system’s implementation domain is considered to be “historic urban landscapes”, i.e., geographical areas with particular cultural features such as traditional settlements, monuments and historical centers, regarded as exceptional universal heritage. In particular, the project’s prime exemplary pilot setup is considered to be operated in specific Greek areas of cultural importance. © 2018 by the authors. Licensee MDPI, Basel, Switzerland

Glocal participatory system for the recording, documentation and promotion of cultural heritage: A greek case-study

The recording, documentation and promotion of local cultural heritage has been the subject of significant research from scientists from various fields such as architecture, anthropology, history, folklore, ethnomusicology, and museology. This paper argues that digital technologies could have a catalytic role concerning the operational part of a holistic–interdisciplinary approach to the maintenance of cultural heritage. Simultaneous and bidirectional recording, documentation and promotion of human histories, material elements of space, personal and collective memories, music, dance, singing and other performances, customs, traditions etc. has the effect of improving the understanding of each place and, therefore, contributing to the establishment of sustainable living conditions and environmental balance. At the same time, it facilitates the process of presenting the place’s local identity as well as its tangible and intangible cultural heritage. The paper proposes the design, the creation and the pilot operation of a glocal hybrid (physical and digital) participatory system for monitoring cultural heritage, which consists of (a) spatial recording and projection constructions (open micro-labs); (b) research and documentation centers; and (c) digital databases and mobile applications for interconnection and diffusion of digital content. The system’s implementation domain is considered to be “historic urban landscapes”, i.e., geographical areas with particular cultural features such as traditional settlements, monuments and historical centers, regarded as exceptional universal heritage. In particular, the project’s prime exemplary pilot setup is considered to be operated in specific Greek areas of cultural importance. © 2018 by the authors. Licensee MDPI, Basel, Switzerland