From images to augmented 3D models: improved visual SLAM and augmented point cloud modeling

This thesis investigates into the problem of using monocular image sequences to generate augmented models. The problem is decomposed to two subproblems: monocular visual simultaneously localization and mapping (VSLAM), and the point cloud data modeling. Accordingly, the thesis comprises two major parts. The First part, including Chapters 2, 3 and 4, aims to leverage the system observability theories to improve the VSLAM accuracy. In Chapter 2, a piece-wise linear system is developed to model VSLAM, and two necessary conditions are proved to make the VSLAM completely observable. Based on the First condition, an instantaneous condition for complete observability, the "Optimally Observable and Minimal Cardinality (OOMC) VSLAM" is presented in Chapter 3. The OOMC algorithm selects the feature subset of minimal required cardinality to form the strongest observable VSLAM subsystem. The select feature subset is further used to improve the data association in VSLAM. Based on the second condition, a temporal condition for complete observability, the "Good Features (GF) to Track for VSLAM" is presented in Chapter 4. The GF algorithm ranks the individual features according to their contributions to system observability. Benchmarking experiments of both OOMC and GF algorithms demonstrate improvements in VSLAM performance. The second part, including Chapters 5 and 6, aims to solve the PCD modeling problem in a geometry-driven manner. Chapter 5 presents an algorithm to model PCDs with planar patches via a sparsity-inducing optimization. Chapter 6 extends the PCD modeling to quadratic surface primitives based models. A method is further developed to retrieve the high-level semantic information of the model components. Evaluation on the PCDs generated from VSLAM demonstrates the effectiveness of these geometry-driven PCD modeling approaches.Ph.D

A Sparsity-Inducing Optimization-Based Algorithm for Planar Patches Extraction from Noisy Point-Cloud Data

Currently, much of the manual labor needed to generate as-built Building Information Models (BIMs) of existing facilities is spent converting raw Point Cloud Datasets (PCDs) to BIMs descriptions. Automating the PCD conversion process can drastically reduce the cost of generating as-built BIMs. Due to the widespread existence of planar structures in civil infrastructures, detecting and extracting planar patches from raw PCDs is a fundamental step in the conversion pipeline from PCDs to BIMs. However, existing methods cannot effectively address both automatically detecting and extracting planar patches from infrastructure PCDs. The existing methods cannot resolve the problem due to the large scale and model complexity of civil infrastructure, or due to the requirements of extra constraints or known information. To address the problem, this paper presents a novel framework for automatically detecting and extracting planar patches from large-scale and noisy raw PCDs. The proposed method automatically detects planar structures, estimates the parametric plane models, and determines the boundaries of the planar patches. The first step recovers existing linear dependence relationships amongst points in the PCD by solving a group-sparsity inducing optimization problem. Next, a spectral clustering procedure based on the recovered linear dependence relationships segments the PCD. Then, for each segmented group, model parameters of the extracted planes are estimated via Singular Value Decomposition (SVD) and Maximum Likelihood Estimation Sample Consensus (MLESAC). Finally, the α-shape algorithm detects the boundaries of planar structures based on a projection of the data to the planar model. The proposed approach is evaluated comprehensively by experiments on two types of PCDs from real-world infrastructures, one captured directly by laser scanners and the other reconstructed from video using structure-from-motion techniques. In order to evaluate the performance comprehensively, five evaluation metrics are proposed which measure different aspects of performance. Experimental results reveal that the proposed method outperforms the existing methods, in the sense that the method automatically and accurately extracts planar patches from large-scaled raw PCDs without any extra constraints nor user assistance.This is the accepted manuscript. The final version is available from Wiley at http://onlinelibrary.wiley.com/doi/10.1111/mice.12063/abstract

PO-274 Photobiomodulation Preconditioning Prevents Hypoxia-ischemia Induced Dyscinesia in a Neonatal Rat Model

Objective Neonatal hypoxia-ischemia (HI) injury caused by oxygen deprivation is the most common cause of severe neurologic deficits and dyscinesia in neonates. The work was designed to evaluate the preventative effect of photobiomodulation (PBM) preconditioning on HI-induced Dyscinesia in a Neonatal Rat Model, and its underlying mechanism of PBM action on brain damage in a HI model in neonatal rats. Methods 10-day-old neonatal Sprague-Dawley rats were randomly divided into 3 groups: (a) control group (animals without ligation); (b) HI group (HI animal with PBM pretreatment); (c) PBM group (HI animal with PBM pretreatment). The hanging wire test and cylinder test were conducted to evaluate the the strength and asymmetry of left (contralateral) paw usage, respectively. The volume shrinkage of the brain was analyzed on postnatal day 29. The neuronal loss, mitochondrial dynamics, mitochondrial fragmentation, cytochrome c release, neuronal apoptosis, dendritic and synaptic injury in hippocampus were tested using the brain collected on postnatal day 16. Results PBM preconditioning significantly attenuated motor function impairment, volume shrinkage, neuron loss, dendritic and synaptic injury after HI. Further mechanistic investigation showed that PBM preconditioning effectively restore HI-induced mitochondrial dynamic changes and inhibit mitochondrial fragmentation, accompanied by a robust suppression of cytochrome c release, and prevention of neuronal apoptosis by inhibition of caspase activation. Conclusions PBM preconditioning can prevent HI induced dyscinesia and brain injury by maintaining mitochondrial dynamics and inhibiting mitochondrial apoptotic pathway. &nbsp

PO-275 Effect of acute photobiomodulation treatment on the recovery of exhaustive exercise-induced motor dysfunction: There is no full text article associated whit this abstract

Objective Photobiomodulation (PBM), originally known as “low-level laser therapy”, has been recognized as an effective methond to relieve pain, reduce inflammtion and improve healing. PBM induces photobiological effect at the the cellular level without thermal and toxic effects. Currently, PBM study on muscle recovery after exercise mainly focouses on the changes of molecular and immunological parameters. This study was designed to analyze the effect of acute PBM treatment on exhaustive exercise-induced behaviorial changes. Methods 1. Sprague-Dawley rats were randomly divided into three groups (n=8, each group): Control group without exhaustive exercise (Cont), Exhaustive exercise group (EE) and acute PBM treatment group (APBM). Acute PBM were conducted immediately using a diode laser with continuous wave (CW) at 808 nm (350 mW/cm2) after exhaustive exercise. Each paws were treated using PBM for 2 minutes. Grisp test were performed 24 hours after exhaustive exercise. The grisp strength score and the hanging time on the rope were recorded and analyzed using Sigmastat. Results 1. Signficant decreases of the grisp strength score and the hanging time were observed in the EE group compared with control group. 2. The motor function in the acute PBM treatment group were significantly improved. Conclusions Acute photobiomodulation treatment with 808 nm laser can signicicantly enchance the recovery of exhaustive exercise-induced motor dysfunction . &nbsp

PO-281 Vibration Training Restores Food Intake and Body Weight in a Rat Model of Depression

Objective Stress is well known to negatively affect body weight and food intake in animal models, but the underlying mechanisms have not yet been well elucidated and effective treatment is lacking. This project was initiated to study the potential beneficial effect of vibration training, a novel neuromuscular training method, in the treatment of depression. Methods Adult Sprague-Dawley male rats were randomly divided into the following three groups: 1) naïve control group, 2) depressive disorder group, and 3) depression with vibration training treatment group. To develop a depression phenotype, rats were individually and gently restricted in a modified, well-ventilated tube for 4 h every day for 21 days. Animals in vibration training treatment group were subjected to 30 min of vibration training (30 Hz, 5 days / week) for continuous 5 weeks. Body weight, physical and mental condition, and food intake were recorded daily and the data were statistically analyzed and compared between groups. Results 1. Daily body weight and food intake measurements revealed that both parameters decreased rapidly after the initiating daily restraint stress, compared with control group.  Intriguingly, both body weight and food intake of the depressive disorder group with 5-week vibration training were significantly improved. 2. The secretion of serotonin and dopamine in animals with chronic restraint stress were decreased compared with normal animals, and this attenuation was significantly prevented by vibration training. Conclusions The present study demonstrates that vibration training is capable of restoring food intake and body weight in a rat model of chronic restraint stress-induced depression

PO-284 Aerobic Exercise Preconditioning Prevents Behavioral Deficits in an Ovariectomized Rat Model of Post-traumatic Stress Disorder

Objective Post-traumatic Stress Disorder (PTSD) occurs in people who suffers reparative shocking, scary, or dangerous event. Evidences demonstrate that PTSD is associated with cognitive decline and depression. In the general population, women tend to show higher incidence of PTSD compared with men. Using the the ovariectomized rat model, the present work was designed to investigate the potential beneficial effect of aerobic exercise on the prevention of PTSD. Methods Adult Sprague-Dawley male rats were randomly divided into the following four groups (n = 8-10 in each group): 1) naïve control group; 2) ovariectomized group (OVX), 3) OVX with PTSD group (OVX + PTSD), 4) OVX + exercise group (OVX + Exe), and 5) OVX + PTSD + exercise (OVX + PTSD + Exe). For exercise pretreatment groups, the rats were subjected to 30 min of treadmill exercise (30 min/day, 5 days / week) for continuous 4 weeks. Open field test and elevated plus maze were used to measure behavioral changes from day 59 to day 66. Hippocampal levels of 17β-estradiol (E2) and brain-derived neurotrophic factor (BDNF) level were measured. Results 1. Results of open field and elevated plus maze test revealed that OVX animals exposed to PTSD showed obvious anxiety-like behavior compared to OVX animals without exercise. Intriguingly, anxiety-like behavior in OVX + PTSD group was significantly improved by aerobic exercise pretreatment in ovariectomized animals after PTSD. 2. Hippocampal levels of E2 and BDNF levels in the OVX + Exe group were significantly increased after aerobic exercise compared to these from OVX without exercise group. Conclusions These findings demonstrated that aerobic exercise preconditioning can efficiently prevent anxiety-like behavior in the ovariectomized rats subjected to PTSD, a mechanism could be associate with the increased levels of E2 and BDNF induced by exercise treatment

Mechanical characteristics research of new asphalt pavement structure based on geogrid

In order to study the mechanical characteristics of new asphalt pavement structural materials, UTM testing machine and Overlay Test (OT) testing machine, four-point fatigue test, tensile test and bending strength test have been carried out on different types of grid asphalt mixtures. The result shows: the addition of different types of grids can effectively improve the mechanical properties of the asphalt concrete pavement structure; geogrid addition can improve the stress on the road surface, improve the strength of pavement materials, it can effectively alleviate early generation of fatigue cracks on the road surface; it can also effectively avoid the problem of rutting damage on the whole road surface after partial damage to the road surface; can effectively promote pavement stress dispersion, improve pavement structure stability, make the pavement structure more stable, improve its service life