Computer world is comprised of images, videos, images both static and animated. These images are built from a set of pixels on a grid. Rendering is a process of creating image from a model. Image rendering is common term in graphics world, most of the work on graphics requires image rendering under certain set of limitations etc. Graphic world I full of new and advance techniques, methodologies, methods, however some assumptions and some limitations are always present in every method/model. Image rendering is a process of creating images from a model with the aid of computer programs.
The model is always based on three dimensional objects which are strictly defined by a language or data structure. These models are always based on some figures and statistical facts. These models contain different angles and different information including geometry, viewpoint, texture, lighting, and shading information. Rendered image produced by a model contain digital information or it always a digital image or raster graphic image.
Rendering process in used in different ways , it is also being used for animated images and other objects. Rendering of an image is also used to calculating different values and effects. Image rendering process is also done by the designers on old films or objects to produce new and refined rendered images from previous images or videos. Image rendering term is widely used in 3D object graphics (a three dimensional representation of geometric data which is stored on computer for rendering old /previous 2D images to produce new and refined form of images.
Image rendering is also widely used for editing films in various fields. Image rendering is used in various fields like architecture, video games, simulators, movie or TV special effects, and design visualization majors. Different techniques and different methods/ models are applied depending upon the limitations and object status to retrieve desired output. Different rendered programs are also available for rendering images and achieving desired output within few minutes.
These programs are available for free and some are available at economical rates. A rendered program is an engineered program depending upon some major and strict principles of graphics and other subjects like light physics, visual perception, mathematics, and software development. Image rendering is also used n movies and animation, in ambition movies, some parts of image must be rendered for producing effective and nice results.
In animation movies frames must be rendered, an any available 3D program animator has also these options by which a designer or animator can easily do image rendering. There are number of different features of image rendering: few of them are as follows: shading, texture-mapping, bump-mapping, fogging/participating medium shadows, soft shadows, reflection, transparency, transparency or opacity, translucency, refraction, diffraction, indirect illumination, caustics.
There are different techniques of mages rendering, few of them are as follows: Scan line rendering and rasterisation, Ray casting, Radiosity, Ray tracing. Academic core of image rendering depends on different factors; some of them are as follows: The rendering equation, The Bidirectional Reflectance Distribution Function, Geometric optics, Visual perception. Past few decades has seen major and vast changes, developments and improvements in the field of image rendering.
Nowadays, there are number of personal level consumer processors are available and number of researches are using this background for producing new and advanced algorithms of in image rendering field. Researchers are using ground realties, keeping in mind the needs and changing requirements of today’s world, user and market on the basis of which they are trying to produce new, cost effective and strong algorithms and image rendering techniques.
This paper will deal the methods, methodologies and their limitation, assumptions of image rendering methods. Number of image rendering methods is available for producing new and refined images from old ones. These refined images are used a lot in number of fields, infect, number of fields are running only because of these rendering images. Number of techniques, methods is available for rendering images, each of which has certain limitation and assumptions, all produce new and unique output based on different calculations and objective. As, it is stated above that number of techniques and methods are available, few of them are briefly described below:
Interactive Fur Shaping and Rendering Using Non uniform-Layered Textures
In this approach, image rendering and refining is done by using non uniform layered texture from which different calculation are obtained and helps in producing desired rendered images (Langley, 2001). In this approach, such system are taken which represents furry surfaces as non uniform layers of texture slices, afterwards which are automatically adjusted layers to produce efficient, high-quality rendering of an image. This method employs layered shadow maps to simulate self-shadowing technique which is helpful in dealing with non uniform layered texture (Kajiya, 1989).
By using these approach interactive tools are used in different ways, interactive tools let users intuitively create and edit furry objects and instantly view the rendered objects. This method is of great significance in producing and editing old images for producing new and refined rendered image. As, this approach uses interactive tools which led a user to create or edit previous picture by using provided tools in simple steps. This approach is time saving approach, its is also cost effective approach however, output sometime do not meet user’s requirements but up to some extent this methods is highly effective(Banks, 1994). This approach also gives opportunity to instant view of user’s rendered image.
Massive-Model Rendering Techniques
There are number of techniques available of model rendering, massive techniques produces results quiet different, as these massive techniques include mixture of different techniques for producing nice and effective output.
According to new approaches, it has been observed that exponentially increasing size of 3D models usually prohibits rendering images using brute force methods. For the solution of this problem, researchers have proposed various output sensitive rendering algorithms to overcome this challenge. This method and massive techniques provides an overview of all these technologies which are always good and helpful for beginners and also helps in producing low profile rendered image (Yoon, 2007). These methods do not need various types of images but are useful in certain situations.
Synergistic Visual/Haptic Rendering Modes for Scientific Visualization
There are number of images and different types of resolution images are available and most of the time animators require dealing with different type of images simultaneously. In that situation animator required some strong and advanced algorithm, approach to fulfill his needs or requirement. Visual Haptic rendering modes allow user to deal with number of different type images at a time. These modes allows user to create and modify different fields according to the needs and requirements of their data.
This Haptic approach allow user to combine Haptic and visual approach interactively and helps them in exploring scalar, vector, and tensor fields, which facilitates their understanding and requirements of the data. In this approach a primary role is based on Haptic interaction method for volume visualization which typically provides support for visual exploration of data and additional information is provided by giving the relief of viewing images instantly. This Haptic approach is suitable for both visualization and modeling applications. Points are directly calculated from the volume data and are consistent of volume rendering methods, it also provides strong co relation between visual and haptic feedback.
In this approach virtual tools are simulated by applying three dimensional filters to explore the data obtained by ray casting method (Sobierajski, 1996). This method is produced by using Phantom Haptic interface. This approach is suitable for both volume of data and the data is widely obtained by volume visualization. This method produces and effective and time saving results and this technique is suitable in number of situations. The use of visual interactive tools makes this technique worthy and time saving. In this approach, data is directly obtained by volume of data and other facts.
Sensation-Preserving Haptic Rendering
In past few decades as tremendous and new changes came in field of graphics particularly in image rendering fields. Researchers had faced a lot of problems in contracting forces and torques between 3D virtual objects. This problem faced by number of researchers was of 6DOf haptic rendering (Baraff, 1994). This 6DOF Haptic rendering divide in two categories i.e.3-DOf forces and 3DOF torques. This method based on the principals of preserving the dominant perceptual factors in haptic exploration. This method applies for simulation the rigid body’s dynamics of haptically manipulated objects using implicit integration.
This method provides higher stability and responsiveness than all other previous methods. Different approaches based on rendering algorithms helps in solving problems of 6-DOF problems (Danzig, 1968).
This method also helps in solving complex 6 DOF structures by using different rendering polygonal methods. A different and effective algorithm for computing contact forces between solid objects to deal with friction. Algorithm deals with both static and dynamic friction. The problem of computing contact forces is not transformed into optimized problem. This algorithm deals with friction in both static and dynamic images (Cottle, 1992). This approach is more reliable, time saving and effective than any other previous approach.
Physically Accurate Haptic Rendering with Dynamic Effects
This approach presents a real time method to render contact force and momentum between two static and rigid bodies taking as account friction and dynamic effects. This approach produces a new method for rigid bodies based on volume rich penalty method. This penalty method applies a spring damper model which is very simple, effective and useful method for real time simulation of multi bodies. There is a limitation that penalty method cannot deal face contact because reflection point cannot be found by this method. Spring damper model is always recommended for solving such problems.
In this method, intersection part of bodies and integrate forces and torques from distributed damper models. This method uses simulator with simple penalty method to resolve the face face contact issue, if haptic interface is attached with simulator, this make animator able to interact haptic interfaces in virtual world (Sato, 2003). This method deals with interactive parts and torques of body and produces effective results. This method applies simple damper method which is useful in number of situations and it also empower user to interact with haptic approaches to virtual world.
Interactive Transfer Function Design Based on Editing Direct Volume Rendered Images
Direct render images are widely used for to reveal structures in volumetric data. DVRIs generated by many volume visualization techniques can only satisfy user’s demands, as number of techniques is using today but all of them are not effective and reliable. So, its’ necessary to use and implement only reliable and good techniques for producing effective results. Applying techniques in a proper way saves a lot of time (Bruckner and Gröller, 2006).
This approach presents a framework of editing of DVRIs which is also used for interactive transfer function. Design. This approach is designed in such a way to provide users the option of fusing multiple features in district DVRI’s into comprehensive one (Chan and Zhou, 2006). This approach also allow user to fuse or sharpen multiple effects of an image. Using this approach a user can easily modify and edit images according to his own desire. This approach also presents options for editing images to produce new rendered images with a combination of smooth and refined animations for focus plus context visualization. This technique is applied on number of images to obtain reliable and accurate results and this technique proved better results than other rendering techniques (Cornea, 2003).
Virtual Change of Illumination Color in Image Based Rendering
This method presents a method of generating images and an extension of image based rendering is followed by a method of generating images correspondence to a virtual change of lighting color. This method offers an additional ability to previous methods that allows generating images by changing lighting orientation. With the help of which number of tasks were done in past few years. Still this approach is applicable in different situations and different conditions. This approach is highly applicable to the virtual varying object material (Kitahashi, 2005).
Illustrative Visualization
This approach presents state-of-the-art visualization techniques which are inspired by different traditional technical and medical illustrations. Such techniques exploit the perception of the human visual system and are designed in keeping an eye of changing needs and requirements of this changing world. The aim of this approach is to provide effective visual abstractions to make the visualization clearly understandable and use it for further processing of image.
Visualization emphasis and abstraction has been used for expressive and attractive presentation from different types of paintings to nowadays scientific and medical illustrations which are designed for actual representation of different images (Stredney, 2005). Many of the expressive techniques used in art are adopted in computer graphics, and are denoted as illustrative or non-photorealistic rendering. There are number of different stroke techniques which are specially designed for image rendering, or brush properties express a particular level of abstraction. Feature emphasis or feature suppression is achieved by combining different abstraction levels in illustrative rendering.
A New IBR Approach Based on View Synthesis for Virtual Environment Rendering
A general IBR image approach (Image Based Rendering) schema which is based on synthesis image of new and obtained viewpoint is presented in this approach. With the giving series of images of an environment on closely spaced two circles viewpoints the proposed algorithm is specially designed to generate perspective intermediate images and new or refined images within the environment in any viewpoint between two circles or between two objects. In this approach the same environment is displayed from the view of a simple camera which is highly controlled by the user.
This approach processes in simple three steps: First, it deals with the ring-like region in between both outer and inner circles can be divided as a set of fan just like sub-regions. This approach emphasizes on finding the fan-like region to encircle the specified viewpoint, then an IBR processing between two images taken by moving camera along optical axis is implemented for producing new and reformed images and to generate two intermediate image; finally, an IBR processing between two images for this approach is always taken by virtual moving camera around the scene which is implemented to generate the destination image with clear view corresponding the specified viewpoint.
Different experiments were done o different type of images for producing nice and effective results. This approach has given a new turn to the image rendering field. This approach is applicable on number of different images and is specially designed for all types of objects (ying Ou, 2006). The results proven this approach one of the best approach for all images and it also helps a lot to user in driving different calculation from objects. This approach is reliable, time saving and always produces perfect and effective results. Environment matters a lot in this rendering as virtual environment produces a great impact on this approach. With the aid of this approach, one can easily compute angles of image and it also helps in dealing with virtual camera images.
Efficient Depth Image Based Rendering with Edge Dependent Depth Filter and Interpolation
This approach provides an efficient depth image based rendering with specially designed edge dependent depth filter for image rendering purpose and interpolation is proposed. The proposed method has the ability to solve the hole-filling problem in DIBR system efficiently and accurately with high quality. The PSNR of the proposed method is better than the previous work which was done by 6 dB.
The object oriented and subjective approach and technique shows that the output quality is better than others. In addition to that, the huge number of instruction cycles were carried to produce effective results but as a results it has observed that 3.7 percent compared with the previous work and this approach produces a best and effective results(Liang-Gee Chen, 2005).
3D Image-Based Rendering Technique for Mobile Handheld Devices
This approach is specifically designed for presenting 3D image based rendering technique for mile and other handheld devices. This method presents a refined architecture for the rendering of 3D scenes and 3D images on different wireless and mobile devices so that mobile devices and other handheld devices can easily present 3D rendered images (Fomel, 2001). This approach is comprises a novel lightweight rendering algorithm and a fault tolerant local cache management mechanism which produces an effective and smooth image after processing.
Both the rendering algorithm and the cache management mechanism are totally based on the some facts and calculation derived from image objects and especially it is based on interpolation model of image-based rendering. This algorithm applies loose restriction on source virtual camera placement which helps in easily capturing of available source data (Tong and Wang, ET, al, 2001). This technique is applied on number of objects for roving its reliability and effectiveness and this technique is quiet successful in delivering smooth images on mobile and handheld devices.
As, this technique is applied on different real and artificial objects so results have shown that the rendering performance of the proposed algorithm is better compared to other known algorithms listed in literature. In addition, the achieved real-time response time obtained from the results makes our algorithm a promising solution for 3D rendering in wireless devices (Chen, 2004). Time saving algorithm for producing rendering of 3D images on mobile devices was the objective of this method. This approach is proved as one of the best approach of image rendering on mobile devices.
Image-based rendering of diffuse, specular and glossy surfaces from a single image
This approach presents a new and different easy method to recover an approximation of the bidirectional reflectance distribution function (BRDF) of the surfaces present in a real scene or movies. This approach results in obtaining glossy and specular images from a single image. This approach was applied on a single photograph and a 3D geometric model of the scene and desired results were obtained (Romanzin, 1993).
This methods results as a presentation of full model of the reflectance properties of all surfaces, which can always be rendered under novel illumination conditions with, for e.g. viewpoint modification obtained from image with the addition of new and derived synthetic objects for this technique. This technique is applied on real and artificial objects for producing a reflectance model using a small number of parameters. These parameters nevertheless approximate the BRDF and are used in the recovery of the photometric properties of diffuse, specular, isotropic complex textured objects (Nelder, 1965).
The input data used in this approach is based on geometric model of the scene including the light source positions and the camera properties which helps in capturing real images from virtual cameras with soft handling, and a single image captured using this camera. This algorithm generates a new synthetic image using classic rendering techniques and massive models, and a hypothesis about the reflectance model of the surfaces (Gervautz, 1996).
Afterwards, it is relatively compares the original image to the new one, and chooses a more complex reflectance model so that if any complex point is available it also compares the difference between the two images the older one and a new one greater than a user-defined threshold. This approach is applied on different objects and different synthetic images which are compared to original ones and some possible application and results we present several synthetic images that are compared to the original ones and some possible applications has increased reality.
A novel image-based rendering method by linear filtering of multiple focused images acquired by a camera array This apporach deals presnets a noval approach of rederning images of an arbitary view image with a focus on the scence consiting two contsnat depths. This method differes from other conventional methods presented earlier.This methods gives a new and unique technique for rendering images. this apporach based on noval approach multiple view images and deals with number of images at a time. This method saves lot of time and produce and effective and smooth rendered image.
Dense Estimation of Surface Reflectance Properties Based on Inverse Global Illumination Rendering
This approach is specifically designed for the solution of past decades problem faced in image rendering field.In augments approach based on virtual, and used for estimating object surface reflectance properties which is very important while rendering different objects under arbitrary illumination conditions. However, this approach is quiet faithful in producing rendered images and are useful in number of situations.faithfully estimating surface reflectance properties is difficult for objects having inter reflections.
The present paper describes a new method for densely estimator approach is widely used for estimating the non-uniform surface reflectance properties of real objects constructed of both lenses which produces two types of surface i.e. convex and concave surfaces having diffuse and specular inter reflections. As, every method has some limitations same in case of this method uses for computing the registered range and surface color texture images were obtained using a laser rangefinder, these ranges data helps a lot in producing and refining new and smooth images after rendering.
In this method, the light positions are first determined in order to take color of images by various ways, which are then used to differentiate between diffuse and specular reflection components of surface reflection, it includes both surfaces convex and concave. Surface reflectance parameters are then computed which based on an inverse global illumination rendering (Machida,2004). Number of experiments were conducted using this approach and it produced great results in image rendering. This approach saves time and money including user’s efforts of computing different type of data for image rendering process.
Image Based Rendering with Stable Frame Rates
There are hundreds of researchers working on image rendering problems and all these researchers using previous background of image rendering as a base of their research. This method deals with an efficient keyframeless image-based rendering technique. This technique is highly effective as it work on key frames which helps in creating motions in images and videos. This Approach used an intermediate image to exploit the coherence among neighboring frames.
The pixels in the intermediate image are first rendered by a ray-casting method which produces a nice and smooth image and then intermediate image was warped to the intermediate image at the current viewpoint and view direction. this method uses offset buffer to record the precise positions of obtained pixels from an intermediate image. in this approach researchers generated every frame in three steps: warping the intermediate image onto the frame, filling in holes, and selectively rendering a group of ?old? pixels. it helps a lot setting dynamically the number of those pixels in the last step, by this way the workload on every frame got balanced and proved effective in producing desired output.the workload at every frame can be balanced.
The pixels generated by the last two steps make great and enhanced contributions to the newly produced intermediate image. Occasional key frames of an image based on image-based rendering which always need to be totally rendered, intermediate images are always need to be partially updated at every frame, by this way the workload on every frame get balanced. This approach can guarantee more stable frame rates and more uniform image qualities in image rendering(Kaufman,2000).
An intermediate image used in this approach can be warped efficiently with the aid of modified incremental 3D warp algorithm which is widely used to render intermediate images.this technique is applied on number of images for checking the output and it produced great and acceptable results in a specific application, this approach also produces great results with the combination of technique with a voxel-based terrain rendering system.
An Efficient Image-Based Rendering Method
This approach works on given set of images of the same scene, this approach propose an efficient and time saving method which produces great and efficient results based on realistically synthesizing a new image observed from a new viewpoint. This approach is also compared with some previous techniques which explicitly reconstruct the 3D geometry of the scene and also use for computing angles and data from images, this approach directly reconstruct the color of each pixel and give it a new color in the new image by utilizing a weighted photo consistency constraint.
This approach uses Global photo consistency constraint by which one pixel is firstly utilized to generate a new color and than it used as a list of plausible colors for each rendered pixel in the newly formed image. By considering the existing pixels of partial occlusion or the deficiencies in the image-formation model, this approach looks like an iteratively update the color for each rendered pixel which highly based on local texture statistics similar to the input images and pixel color in input image.This technique is also applied on number of images reliability and to show proved results and compared observation with different methods.
Image-Based Rendering Using Parametrized Image Varieties
In this approach of image rendering user will find that this approach addresses the problem of characterizing the group of all images of a set of m points and n lines cached by a weak perspective camera. by taking it in the account of constraints related with calibrated cameras, this approach shows that the corresponding image space can be easily presented in a form of six dimensional and parametrized form and can be embedded in {cal R}^{2(m+n)} and can be easily parametrized by the image positions of three reference points (Hartley, 1992).
The coefficients which defined this parametrized image variety and coefficients can also be estimated from a sample of images of a scene via linear and non-linear least squares(Ayache,1997). This approach has been implemented on various images and extensively tested on real data sets for proven results.
In this paper it has seen that a huge number of methods are available for images rendering. in graphics field its very common term used in various situations. for that one need to understand the basics of graphics and other related terms (Fitzgibbon, 1998). there are number of algorithms are present for image based rendering and video based rendering but there is a need of proper understanding and implementation of image based rendering techniques (Genc, 1999). This world has become a world of changes, every next moment graphics field is facing new challenges so there is a need of proper and strong understanding and implementation of image rendering techniques and methods in proper way (Faugeras,1995).
In this paper, we have seen number of methods of image rendering, each method has its own effectiveness and efficiency. Each method has its own assumption and limitation according to which it is required to applied. Few methods computes different data from an image and used in further processing.This approach of calculating data and figures, angles from images is a time saving approach and it helps in producing sharp, smooth and effective results. So, there is a need of proper on time decision of choosing algorithm and technique according to one’s requirements.
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