Lijun Xie

Harmful Gas Recognition Exploiting a CTL Sensor Array

In this paper, a novel cataluminescence (CTL)-based sensor array consisting of nine types of catalytic materials is developed for the recognition of several harmful gases, namely carbon monoxide, acetone, chloroform and toluene. First, the experimental setup is constructed by using sensing nanomaterials, a heating plate, a pneumatic pump, a gas flow meter, a digital temperature device, a camera and a BPCL Ultra Weak Chemiluminescence Analyzer. Then, unique CTL patterns for the four types of harmful gas are obtained from the sensor array. The harmful gases are successful recognized by the PCA method. The optimal conditions are also investigated. Finally, experimental results show high sensitivity, long-term stability and good linearity of the sensor array, which combined with simplicity, make our system a promising application in this field.

A novel radiometric projector compensation algorithm based on Lambertian reflection model

In this paper, a novel radiometric compensation algorithm based on Lambertian reflection model is proposed to neutralize the visual perception of colors and textures which are intrinsic to the projection display surface. The algorithm uses a calibration method of advanced coded structure light to determine the geometric mapping between corresponding points in the projector-camera system. Concrete analysis of the dynamic range of projectors is applied to obtain the intensity limits of the input image. Consequently, the Lambertian reflection model is constructed for each point to compute the radiometric compensation function between displayed images and camera captured images. Experimental results show that this algorithm can effectively correct color inaccuracy of projection on arbitrary textured surfaces, and observers almost hard to notice visible artifacts of projected images.

Facial Features Extraction based on Active Shape Model

Active shape model (ASM) is an image searching method based on statistical model, which is widely used to extract features. The classical ASM model includes the shape model and the local profile model. The main merit of ASM model is using statistics to contribute model of specific target image, by introducing prior knowledge on awaiting extraction target object, limiting the searching result in the variable range. These characteristics make it suitable for any similar object’s feature. Experimental results show that the algorithm can extract facial features rapidly and have higher accuracy

An efficient projection defocus algorithm based on multi-scale convolution kernel templates

The focal problems of projection include out-of-focus projection images from the projector caused by incomplete mechanical focus and screen-door effects produced by projection pixilation. To eliminate these defects and enhance the imaging quality and clarity of projectors, a novel adaptive projection defocus algorithm is proposed based on multi-scale convolution kernel templates. This algorithm applies the improved Sobel-Tenengrad focus evaluation function to calculate the sharpness degree of intensity equalization and then constructs multi-scale defocus convolution kernels to remap and render the defocus projection image. The resulting projection defocus corrected images can eliminate out-of-focus effects and improve the sharpness of uncorrected images. Experiments show that the algorithm works quickly and robustly and that it not only effectively eliminates visual artifacts and can run on a self-designed smart projection system in real time but also significantly improves the resolution and clarity of the observer’s visual perception.

An Intelligent Projection System Adapted to Arbitrary Surfaces

This paper designs and implements an intelligent projection system which automatically calibrates projected distorted images on an arbitrary surface. It consists of a projector, computer, camera and tilt sensor. Binary-coded structured light is projected to recognize the geometric shape of a projected surface. Tilt sensor determines a appropriate visual angle and an effective projected area. Discrete mapping algorithm is proposed to warp the original projected image which helps to compensate the distortion of a projected surface. The whole process takes less than two minutes. Experimental results show that this intelligent system does not only adapt to the variation of projector pose, but also any arbitrary projected surface automatically.

Projecting Tetrahedra with a Simplified Basis Graph

The basis graph with five vertices has been commonly used in the GPU-accelerated Project Tetrahedra algorithm because of the inability to create or delete vertices within a vertex program and the fixed topological constraints of submitted vertices. However, it is so complicated that projecting a tetrahedron need to render four triangles. In this paper, we present a novel algorithm with a simplified four-vertex basis graph which decomposes a tetrahedral silhouette into two triangles. In contrast with previous algorithms, our algorithm can reduce the vertices and the triangles to be rendered and computational overhead on vertex processors, and therefore can remarkably improve the interactive rendering performance. Experimental results demonstrate that our algorithm can sort and render up to 2.30 - 6.16 Mtets/sec for a frame buffer resolution in 512 times 512.

A Novel Pointcloud-based Isosurface Extraction

In this paper, we present a novel approach of hardware-accelerated pointcloud-based isosurface extraction on tetrahedral cells. In contrast to previous methods, our method takes advantage of programmable capability on the modern graphics hardware to render the isosurface silhouette and reduces the video memory consumption per tetrahedron. We achieve this by using a GPU-based geometry-generating method called fat-point technique. We classify tetrahedra into three isosurface cases and compute corresponding parameters in vertex processors, and then generate implicit isosurface silhouette in fragment processors. Utilizing the high performance OpenGL vertex buffer objects, our algorithm can achieve a rendering rate of three million tetrahedra per second.

A Virtual Plant Ecosystem Featuring Parallel Computing and Distributed Visualization

A parallel plant ecosystem simulation, running on a computer cluster with commodity graphic cards, is performed to simulate and visualize large groups of plants. With a scalable architecture, the system can simulate very large and complex plant ecosystem in much shorter time than the traditional. The extreme complexity is first simplified by using multilevel models, and then dividing into multiple parts and simulating parallel. The entire simulation process is visualized in an immersive mode approximately in real time by rendering the results locally and concatenated to a large display wall

EEMAS: An enabling environment for multidisciplinary application simulations

EEMAS environment is a problem-solving environment for multidisciplinary application simulations. Within the EEMAS, there are four categories of modules involved, namely pre-processing module, computing module, post-processing module, and platform control module. The EEMAS is developed for complex and large-scale simulations to take advantage of powerful parallel and distributed computing technologies. All the modules are coupled through a software bus, which maintains the share memory and makes the modules integrated seamlessly. In the present paper, detailed design principles and applications of the EEMAS are addressed.

Aerospace Numerical Simulation and Digital Prototyping Technologies

A High End Digital Prototyping system (HEDP) designed for aerospace numerical simulation is introduced in this paper. This system is a problem solving environment equipped with capability of parallel mesh generation, immersive visual steering, large‐scale visualization and parallel computation. All enabling technologies are realized as separate modules and coupled through a software bus, which makes them integrated seamlessly. Detailed design principles and a numerical simulation of turbulent combustion in the HyShot Scramjet whitin the HEDP system is addressed.