Chia-Yen Chen

Image Stitching - Comparisons and New Techniques

This work describes the steps involved in the generation of a panoramic image, i.e., image acquisition, image registration and image merging. Different approaches for each of these steps are discussed and compared. The resultant images from image registration and image merging are quantitatively evaluated to provide an indication to the performance of the different methods. The methods provided in this work can be used to generate panoramic images for the use of interactive panoramic viewing of images, architectural walk-through, and other applications associated with the modelling of 3D environments.

Adaptive 3D Reconstruction system with improved recovery of miscoded region to automatically adjust projected light patterns

The paper proposes an adaptive system for 3D object reconstruction which analyzes the shape and colours of the object and automatically designs suitable projection patterns for more effective reconstruction. The system is also able to detect regions with details and adaptively provides higher resolution reconstructions for such regions. A method that interpolates the ambiguous or miscoded regions based on the monotonicity of camera-projector correspondence relationship is also proposed to improve the accuracy of the system. Experiments have been performed to demonstrate the effectiveness of the proposed approaches and to show that the proposed system is able to overcome inflexibilities in traditional structured lighting approaches.

Optimal capacitor control for unbalanced distribution systems with distributed generations

An unbalanced three-phase optimal capacitor control algorithm taking the mathematical models of Distributed Generations (DGs) into account is proposed in the paper. The formulations and solution procedures of the optimal capacitor planning and real-time capacitor control are both derived. The special topological characteristics of distribution networks are fully exploited to develop the proposed optimal capacitor control formulations. According to the characteristics of output power, DGs can be specified as constant power factor model, constant voltage model or variable reactive power model in the system analysis. Different types of DGs have different reactive power output characteristics, the mathematical formulations of different models are integrated into the proposed optimal capacitor control method. Besides, the variation of DGspsila energy sources will actually influence on the planning and operation of distribution feeders; therefore, it is also discussed in this paper. Test results show that the proposed method can integrate DGs into optimal capacitor planning and operation effectively and efficiently, and have great potential to be utilized in the future smart-grid applications.

Shape from Photometric Stereo and Contours

In this work, we propose an alternative approach to 3D shape recovery by combining photometric stereo and shape from contours methods. Surfaces recovered by photometric stereo are aligned, adjusted and merged according to a preliminary 3D model obtained by shape from contours. Comparisons are conducted to evaluate the performances of different methods. It has been found that the proposed approach provides more accurate shape recovery than the photometric stereo and shape from contours methods.

Albedo recovery using a photometric stereo approach

This paper describes a method for the estimation of surface reflectance values using a photometric stereo approach. Evaluations show that surfaces rendered with reflectance values calculated by the proposed method have more realistic appearances than those with constant albedo.

Assessment of In-Cloud Enterprise Resource Planning System Performed in a Virtual Cluster

This paper introduces a high-performed high-availability in-cloud enterprise resources planning (in-cloud ERP) which has deployed in the virtual machine cluster. The proposed approach can resolve the crucial problems of ERP failure due to unexpected downtime and failover between physical hosts in enterprises, causing operation termination and hence data loss. Besides, the proposed one together with the access control authentication and network security is capable of preventing intrusion hacked and/or malicious attack via internet. Regarding system assessment, cost-performance (C-P) ratio, a remarkable cost effectiveness evaluation, has been applied to several remarkable ERP systems. As a result, C-P ratio evaluated from the experiments shows that the proposed approach outperforms two well-known benchmark ERP systems, namely, in-house ECC 6.0 and in-cloud ByDesign.

Geometric calibration of a multi-layer LiDAR system and image sensors using plane-based implicit laser parameters for textured 3-D depth reconstruction

The paper proposes the calibration of a LiDAR-camera system that consists of a multi-layer laser rangefinder device and a pair of video cameras. The method calibrates the intrinsic laser parameters and the extrinsic parameters of the integrated LiDAR-camera system. Using a linear form, the dimensionality of the calibration parameter space is reduced in the plane-based least square model. The optimal laser intrinsic parameters can be determined during the optimization of the extrinsic parameters, without being explicitly modeled. However, due to limited FOV of the cameras, the reduced model may lead to a solution that cannot be generalized to the working space. Hence, we use additional scene planes to improve the determination of intrinsic laser parameters. Overall performance is improved if calibration targets can be accurately estimated from the cameras. Results indicate a reduction of 50% in the flatness error is achievable and running time of the process is also decreased.

Power system vulnerability assessment considering Energy Storage Systems

Vulnerability assessment is one of the main issues for power system planning and operation. Recent research reveals that Energy Storage Systems (ESSs) have a great potential to be used to mitigate power system vulnerability. A vulnerability assessment is proposed in this paper to calculate the impact factors for power systems based on generator and line outages. A Bus Impact Severity (BIS) analysis is then designed and used to find the vulnerable buses in the power system. The buses with larger BIS values as defined in this paper can be considered as the better locations for ESS placement. Test results show that the ESS placement in the vulnerable buses can mitigate system vulnerability effectively.

Extrinsic calibration of a multi-beam LiDAR system with improved intrinsic laser parameters using v-shaped planes and infrared images

In this paper we present a novel method for the calibration of LiDAR-camera systems. The method uses infrared (IR) images to establish laser-pixel correspondences between a multi-layer laser scanner and an IR image sensor. Based on the established correspondences, the intrinsic parameters of the LiDAR system and of the camera as well as the extrinsic parameters are adjusted. The proposed method works in a two-stage manner. The linear estimation of the extrinsic parameters are first obtained using an efficient PnP algorithm, while in the second stage the extrinsic and intrinsic parameters are optimized using a nonlinear algorithm. Experiments show promising results.

Improving Optical Flow Using Residual and Sobel Edge Images

Optical flow is a highly researched area in low-level computer vision. It is a complex problem which tries to solve a 2D search in continuous space, while the input data is 2D discrete data. Furthermore, the latest representations of optical flow use Hue-Saturation-Value (HSV) colour circles, to effectively convey direction and magnitude of vectors. The major assumption in most optical flow applications is the intensity consistency assumption, introduced by Horn and Schunck. This constraint is often violated in practice. This paper proposes and generalises one such approach; using residual images (high-frequencies) of images, to remove the illumination differences between corresponding images.