Modeling environment using multi-view stereo

In this work, we study the potential of a two-camera system in building an understanding of the environment. We investigate, if stereo camera as the sole sensor can be trusted in real time environment analysis and modeling to enable movement and interaction in a general setting. We propose a complete pipeline from the sensor setup to the final environment model, evaluate currently available algorithms for each step, and make our own implementation of the pipeline. To assess real world performance, we record our own stereo dataset in a laboratory environment in good lighting conditions. The dataset contains stereo recordings using different camera angles concerning the movement, and ground truth for the environment model and the camera trajectory recorded with external sensors. The steps of our proposed pipeline are as follows. 1) We calibrate two cameras using de facto method to form the stereo camera system. 2) We calculate depth from the stereo images by finding dense correspondences using semi global block matching and compare results to a recent data driven convolutional neural network algorithm. 3) We estimate camera trajectory using temporal feature tracking. 4) We form a global point cloud from the depth maps and the camera poses and analyze drivability in indoors and outdoors environments by fitting a plane or a spline model, respectively, to the global cloud. 5) We segment objects based on connectivity in the drivability model and mesh rough object models on top of the segmented clouds. 6) We refine the object models by picking keyframes containing the object, re-estimating camera poses using structure from motion, and building an accurate dense cloud using multi-view stereo. We use a patch-based algorithm that optimizes the photo consistency of the patches in the visible cameras. We conclude that with current state of the art algorithms, a stereo camera system is capable of reliably estimating drivability in real time and can be used as the sole sensor to enable autonomous movement. Building accurate object models for interaction purposes is more challenging and requires substantial view coverage and computation with the current multi-view algorithms. Our pipeline has limitations in long-term modeling: drift accumulates, which can be dealt with by implementing loop closure, and using external information such as GPS. Data wise, we inefficiently conserve complete information, while storing compressed presentations such as octrees or the built model can be considered. Finally, environments with insufficient texture and lighting are problematic for camera-based systems and require complementary solutions

Total knee arthroplasty in a fast-track setting: reasons and risk factors for 90-day readmission

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Reply to Comment on Saku et al. : Reasons and risk factors for ninety day re-admission following primary total knee arthroplasty in a high-volume centre

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A Consultation Phone Service for Patients With Total Joint Arthroplasty May Reduce Unnecessary Emergency Department Visits

Background: Different measures for reducing costs after total joint arthroplasty (TJA) have gained attention lately. At our institution, a free-of-charge consultation phone service was initiated that targeted patients with TJA. This service aimed at reducing unnecessary emergency department (ED) visits and, thus, potentially improving the cost-effectiveness of TJAs. To our knowledge, a similar consultation service had not been described previously. We aimed at examining the rates and reasons for early postdischarge phone calls and evaluating the efficacy of this consultation service. Methods: During a 2-month period, we gathered information on every call received by the consultation phone service from patients with TJAs within 90 days of the index TJA procedure. Patients were followed for 2weeks aftermaking a call to detectmajor complications and self-initiated EDvisits. Datawere collected fromelectronic medical charts regarding age, gender, type of surgery, date of discharge, and length of hospital stay. Results: We analyzed 288 phone calls. Calls were mostly related to medication (41%), wound complications (17%), and mobilization issues (15%). Most calls were resolved in the phone consultation. Few patients (13%) required further evaluation in the ED. The consultation service failed to detect the need for an ED visit in 2 cases (0.7%) that required further care. Conclusion: The consultation phone service clearly benefitted patients with TJAs. The service reduced the number of unnecessary ED visits and functioned well in detecting patients who required further care. Most postoperative concernswere related to prescribed medications, wound complications, and mobilization issues. (c) 2017 Elsevier Inc. All rights reserved.Peer reviewe

Osteosynteesimateriaalin poisto aikuisilta

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Potilaiden yhteydenotot leikanneeseen yksikköön lonkan- ja polven tekonivelleikkauksen jälkeen

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Polviluksaatioihin liittyvien peroneus ja tibialis hermovammojen diagnostiikka, vaikeusaste ja toipumisennuste

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Nilkan avomurtumat : esiintyvyys, hoito ja komplikaatiot

Open ankle fractures are rare injuries with a high incidence of wound complications and infection related morbidity. The aim of this study was to evaluate the demographic characteristics, outcomes, and complications of patients treated for open ankle fractures at a level-1 trauma center from 2006 to 2011. We identified 137 open ankle fractures from a cohort of 3041 consecutive operatively treated ankle fractures. The mean age of patients was 60 years and 56% were women. Only 20% of the fractures were the result of high-energy trauma. Most of the fractures were Weber type B with a medial sided wound. Immediate internal fixation was performed in 82% of patients, and the wound was primarily closed in the majority of cases (80%). The incidence of deep infection and postoperative wound necrosis was 17% and 18%, respectively. Older patients did not have an increased risk of complications. The results showed that younger patients are more likely to suffer an open ankle fracture resulting from high-energy trauma, leading to more complications and subsequent increased resource utilization