A Generic Image Processing Pipeline for Enhancing Accuracy and Robustness of Visual Odometry.

The accuracy of pose estimation from feature-based Visual Odometry (VO) algorithms is affected by several factors such as lighting conditions and outliers in the matched features. In this paper, a generic image processing pipeline is proposed to enhance the accuracy and robustness of feature-based VO algorithms. The pipeline consists of three stages, each addressing a problem that affects the performance of VO algorithms. The first stage tackles the lighting condition problem, where a filter called Contrast Limited Adaptive Histogram Equalization (CLAHE) is applied to the images to overcome changes in lighting in the environment. The second stage uses the Suppression via Square Covering (SSC) algorithm to ensure the features are distributed properly over the images. The last stage proposes a novel outliers rejection approach called the Angle-based Outlier Rejection (AOR) algorithm to remove the outliers generated in the feature matching process. The proposed pipeline is generic and modular and can be integrated with any type of feature-based VO (monocular, RGB-D, or stereo). The efficiency of the proposed pipeline is validated using sequences from KITTI (for stereo VO) and TUM (for RGB-D VO) datasets, as well as experimental sequences using an omnidirectional mobile robot (for monocular VO). The obtained results showed the performance gained by enhancing the accuracy and robustness of the VO algorithms without compromising on the computational cost using the proposed pipeline. The results are substantially better as opposed to not using the pipeline.

Correction: Osman, M., et al. A Novel Online Approach for Drift Covariance Estimation of Odometries Used in Intelligent Vehicle Localization. Sensors 2019, 19, 5178.

The authors wish to make the following corrections to this paper [...].

Trocar assisted distal shunt tube insertion with intra-operative X-Ray confirmation.

Trocar assisted distal shunt catheter placement could be an alternative to mini-laparotomy or laporoscopy with good results in comparison to other procedures. Objects: We report our experience with trocar assisted distal shunt tube placement with intraoperative x-ray to rule-out misplacement. Methods: Patients having peritoneal distal catheter site placement for ventriculo-peritoneal or lumbo-peritoneal shunts presenting to Dr. Soliman Fakeeh Hospital, Jeddah, Saudi Arabia, over 27 months' period between October 2016 and December 2018. Results: We performed 65 procedures on 58 patients with mean age of 11 years. The main etiology was congenital hydrocephalus with and without meningeocele followed by post hemorrhagic hydrocephalus and idiopathic intracranial hypertension. Two patients developed shunt infection and one case was complicated by bowel injury. No patient showed pre-peritoneal shunt tube malposition. Conclusion: Trocar-assisted distal shunt tube insertion is a good option in shunt procedures for operation time and infection risk. However, we do not recommend usage of trocar in patients with previous abdominal surgery as adhesions may increase the risk of visceral perforation.

A Novel Online Approach for Drift Covariance Estimation of Odometries Used in Intelligent Vehicle Localization.

Localization is the fundamental problem of intelligent vehicles. For a vehicle to autonomously operate, it first needs to locate itself in the environment. A lot of different odometries (visual, inertial, wheel encoders) have been introduced through the past few years for autonomous vehicle localization. However, such odometries suffers from drift due to their reliance on integration of sensor measurements. In this paper, the drift error in an odometry is modeled and a Drift Covariance Estimation (DCE) algorithm is introduced. The DCE algorithm estimates the covariance of an odometry using the readings of another on-board sensor which does not suffer from drift. To validate the proposed algorithm, several real-world experiments in different conditions as well as sequences from Oxford RobotCar Dataset and EU long-term driving dataset are used. The effect of the covariance estimation on three different fusion-based localization algorithms (EKF, UKF and EH-infinity) is studied in comparison with the use of constant covariance, which were calculated based on the true variance of the sensors being used. The obtained results show the efficacy of the estimation algorithm compared to constant covariances in terms of improving the accuracy of localization.

Secondary Arachnoid Cyst - A Late Complication of Craniotomy: A Case Report and Review of Literature.

Arachnoid cyst can be defined as cerebral-spinal fluid entrapment within the central nervous system. It may occur primarily as a congenital malformation or secondary as a complication following trauma, infection, bleeding, or surgical manipulation. Congenital arachnoid cyst usually asymptomatic and cause no pressure symptoms. No treatment is needed unless size increase and cause pressure symptoms and increased intracranial pressure. We report a case presented to the hospital with neurological signs of increased intracranial pressure, 3 years Post aborted craniotomy for meningioma resection. Radiological imaging showed postoperative newly developed arachnoid cyst with mass effect. He underwent the urgent cerebral spinal fluid diversionary procedure with cystoperitoneal shunt.

Spindle Cell Oncocytoma of the Anterior Pituitary Presenting with an Acute Clinical Course Due To Intraventricular Hemorrhage. A Case Report and Review of Literature.

BACKGROUND Spindle cell oncocytoma (SCO) is a rare nonfunctioning neoplasm of the adenohypophysis, and was first described in 2002. SCO has been categorized as a separate entity by the 2007 World Health Organization (WHO) and is classified as a Grade 1 tumor of the central nervous system (CNS). Review of the literature has shown that 33 cases of SCO have been reported to date, and most of them presented with a mass effect or with panhypopituitarism. However, all reported cases have described the tendency of SCO to be hypervascular on imaging and histology. We detail the first reported case of SCO to present with acute symptoms (pituitary apoplexy) and intraventricular hemorrhage, and review the literature on SCO. CASE REPORT We report the case of 56-year-old man who presented suddenly with a severe headache and an altered level of consciousness. Brain magnetic resonance imaging (MRI) showed a suprasellar mass with hemorrhagic areas within the tumor and bleeding into the lateral ventricle with chiasmal and hypothalamic compression. The patient underwent urgent craniotomy, tumor resection and placement of an external ventricular drain (EVD). Histology and immunohistochemistry supported a diagnosis of SCO. CONCLUSIONS SCO of the adenohypophysis should be considered in patients who present suddenly with symptoms of pituitary apoplexy and intraventricular hemorrhage which may worsen the prognosis.