Image Generation Algorithm Research Articles

Viewpoint Vector Rendering for Efficient Elemental Image Generation

This paper presents a fast elemental image generation algorithm, called the Viewpoint Vector Rendering (VVR), for the computer-generated integral imaging system. VVR produces a set of elemental images in real-time by assembling the segmented area of the directional scenes taken from a range of viewpoints. This algorithm is less affected by system factors such as the number of elemental lens and the number of polygons. It also supports all display modes of the integral imaging system, real, virtual and focused mode. This paper first describes the characteristics of integral imaging system. It then discusses the design, implementation, and performance evaluation of the VVR algorithm, which can be easily adapted to render the integral images of complex 3D objects.

STATE OF THE ART IN THE REALISTIC MODELING OF PLANT VENATION SYSTEMS

The modeling of plants is an active area of research in computer graphics and the geometrical modeling of veins is essential for obtaining plant images with a realistic appearance. The venation patterns determine the anisotropy of plant tissues, and affect the shadowing and masking of light incident on these tissues, hence the images. The current trend in the area of plant image generation is to aim for realism using biologically-based and predictable algorithms. Such algorithms do not depend on ad hoc parameters that have to be tuned whenever a new image is being generated. A number of plant image generation algorithms are now available in the literature that have achieved an impressive level of sophistication in many aspects, generating realistic looking images. One notable exception is the geometrical modeling of veins. This remains as an open problem in computer graphics. In this paper we review the state of art of the realistic simulation of plant venation systems from a geometric modeling perspective and propose a specified set of requirements for evaluating possible solutions for this problem.

Geometric processing of hyperspectral image data acquired by VIFIS on board light aircraft

The Variable-Interference-Filter Imaging Spectrometer (VIFIS) is an airborne imaging system. Unlike usual airborne spectrometers, the image acquisition of VIFIS is based on 2D sensors with its pixel spatially registered to different passing wavelengths. The correction of perturbations upon the VIFIS platform, required by the hyperspectral image generation, relies solely on the information extracted from the 2D pushbroom image flow. In this paper, we present an analysis of the distortions of the pushbroom scan caused by perturbations upon the platform. Hyperspectral image generation algorithms and band registration methods are also discussed. A practical pre-processing approach is developed to automatically track the displacements and generate up to 64 hyperspectral bands. Finally, a pre-processing example is presented as a demonstration of the overall methodology.

Shape-sequence-based key image generation algorithm for browsing and retrieval of video clips

A new shape-sequence-based algorithm that can effectively generate key images from video clips is introduced. Generated key images can be used as the feature information in the browsing and retrieval of video clips from a multimedia database. Experiments with MPEG-7 data sets were performed, and the results are compared with existing methods.

３次元画像情報技術 多眼ステレオ法を用いた運動視差の再現可能な３次元画像表示 表示画像の生成と評価

We propose a 3D display system which can present real scenes with realistic motion parallax. In the sensing part, a scene is observed by using a camera matrix. An excellent stereo algorithm SEA recovers the depth information of the scene with the density and the sharpness required for high quality image generation. In the display part, 2D images from the viewing position of the observer are generated and presented with proper motion parallax. A novel algorithm to determine the view parameters suitable for reproducing the motion parallax on a fixed screen and an image generation algorithm which can cope with arbitrary viewing positions are described. Evaluation of the proposed algorithms has been done by using the prototype system.

Smooth B-spline illumination maps for bidirectional ray tracing

In this paper we introduce B-spline illumination maps and their generalizations and extensions for use in realistic image generation algorithms. The B-spline lighting functions (i.e., illumination maps) are defined as weighted probability density functions. The lighting functions can be estimated from random data and may be used in bidirectional distributed ray tracing programs as well as radiosity oriented algorithms. The use of these lighting functions in a bidirectional ray tracing system that can handle dispersion as well as the focusing of light through lenses is presented.

Radar tomography for the generation of three-dimensional images

Computer-aided tomography is normally a process by which a 2D cross-sectional image of an object is obtained by illuminating it from many different directions in a plane. For the case of radar imaging, microwave energy reflected by the object is processed to produce an image which maps the object's radar cross-section (RCS) density into the image plane. Each observation provides a 1D projection of the RCS density. The Fourier slice theorem states that the Fourier transform (FT) of each projection is equal to the functional value of the 2D FT of the RCS density along a related projection. By accumulating the FT of many 1D projections, it is possible to accumulate a sample representation of the FT of the RCS density. The image can then be obtained using the backprojection algorithm by taking the inverse FT of the sampled transform function. The authors extend the tomographic technique to the generation of 3D images from 1D range profiles. It is seen that the Fourier slice theorem, the backprojection image generation algorithm, and the backprojected function are useful concepts in the interpretation of 3D imagery. Point spread functions (PSFs) for various radar and observation parameters are illustrated.

Computer Generated Copper Plates

AbstractMaking computer generated copper plates with image generation algorithms is presented. The method uses a kind of volume texturing in connection with image processing algorithms, and is suitable for implementation in a ray tracing algorithm. Experience shows that this method is especially interesting for illustrations in books and for generating icons on user interfaces.

Real-time display and manipulation of 3-D medical objects: The voxel processor architecture

The fundamental problems associated with the interactive display, manipulation, and editing of three-dimensional (3-D) objects obtained from medical imaging systems such as CT, PET, and MRI are addressed. Software, hardware, and firmware techniques for shaded graphics display of medical objects are described and evaluated in terms of flexibility and performance. A special purpose multiprocessor architecture (the Voxel Processor architecture) developed specifically for medical research, clinical diagnosis, and surgical planning is presented. The Voxel Processor implements a shaded graphics display system with rotation, scaling, translation, slice planes and tone scale transformations on gray-scale data in true real time. The high-speed image generation algorithms exploit the ability to partition object space and require only simple arithmetic and logical operations. Minimal preprocessing steps are required to prepare object data for the Voxel Processor, and the data are always readily accessible for analysis or editing. The architecture is highly structured and is ideally suited for VLSI implementation.

Spinal cord injury: optimization of computerized tomography image factors for accuracy

Computerised tomography (CT) scanning has become an accepted diagnostic method in evaluation of patients with spinal cord injury and has become increasingly important in the assessment of the vertebral column, spinal cord, and brain. Since CT images are graphic representations of generated computer mathematical data viewed with variable window and level selections (display factors), various image representatations are possible and potentially erroneous objective and subjective conclusions from viewing and measuring anatomical findings can result if an appreciation of this potential variability is not understood. Additionally, the CT image can be reconstructed from a variety of mathematical algorithm selections, which can enhance or diminish aspects of tissue contrast (smoothing or edge enhancement). Optimization of these factors, (window and level selection for viewing, and image generation algorithm), is especially important if detection and measurement of objective structures are to be reliable.The authors studied otpimization of algorithm selection and display factors (window and level selection), with a phantom designed to mimic spinal column, spinal cord and subarachnoid space. Varying concentrations of metrizamide in the phantom were scanned.With the G.E. 8800 Scanner, the bone algorithm was found to be the optimum algorithm for optimum spinal cord images if the measured metrizamide CT attenuation number was greater than 150-200. With a metrizamide CT attentua-tion number less than 150 the soft tissue algorithm was optimum. Window centre (level) selection greatly influenced the measurement of cord size, whereas window width did not. The appropriate window centre (level) selection is the mean between the metrizamide CT attenuation number and the cord CT attenuation number.The clinical application of these findings is summarized, and includes: Patients with metrizamide CT studies that require accurate measurement of spinal cord size or measurement of spinal cord cyst size (post-traumatic cystic myelopathy). Significant errors are possible if the formula for appropriate window centre selection is not followed. Additionally, the use of the bone algorithm requires higher contrast for accuracy, thus if metrizamide concentrations are weak, erroneous interpretations are possible. The authors also found that in the presence of metal (rods, screws or plates) the bone algorithm increased artifacts in CT, thus should not be used in this situation but rather the soft tissue algorithm must be used when metal is present to minimize artifacts.