Rendering is the process of generating an image from a model, by means of a digital content computer software package (or application as they are more commonly known). Sample programs can include Autodesk 3D Studio Max, Autodesk Maya, Avid Softimage XSI, Maxon Cinema4D, Newtek Lightwave to name just a few. The model is a description of three dimensional objects in a defined language or data structure. This defined language or data structure contains geometry, viewpoint, texture and lighting information. The final outputted (or rendered) image is a digital or raster graphics image. The term Rendering may also be used to describe the process of calculating effects in a video editing file to produce final video output (such as in Adobe Premiere Pro or Adobe After Effects)
Rendering has uses in computer and video games, simulators, movie or TV special effects and design / architectural visualisation. Each market sector (or industry) requires a slightly different balance of features and techniques in order to produce the best output. As a product, a wide variety of software renderer's are available (For example: Splutter fish's Brazil, Autodesk's Mental Ray, Next Limit Technology's Maxwell Renderer, Chaos Group's Vray and NVIDIA's Gelato etc). Some are integrated into larger modeling and animation packages (like Mental Ray into Autodesk 3D Studio Max and Maya), and some are separate renderer's or plug-ins that work with their respective modeling applications (like Splutter Fish's Brazil, Chaos Group's Vray and Next Generation Technologies Maxwell Render). On the inside a software renderer is a carefully engineered program, based on a selective mixture of disciplines related to: light physics, visual perception, mathematics and software development; proving the theory that different renderer's are better for certain types of rendering.
In the case of 3D graphics, rendering and pre-rendering is a slow process, as is real-time rendering.. Rendering & Pre-rendering is a computationally intensive process that is typically used in movie creation and highly detailed animation or visualisation scenes. Real-time rendering is usually done for 3D interactive video games (console based Microsoft XBox360, Sony Playstation 3 etc). These rely on the use of specialist graphics cards with 3D hardware accelerators that are built into the consoles and are specially designed for the product (not mainstream).
Rendering Usage: When the pre-image or model data (a wire frame sketch usually) is complete, rendering is used to create the graphical image or animation frame output. This rendering process turns the simple wire frame model into the detailed output by adding bitmap textures or procedural textures, lights, bump mapping, and relative position geometry to each object. The result is a completed image or frame that the designer can see. Containing enough detail and realism so that it can be used throughout a required project.
For movie animations and 3D visual walk through's (Architectural 3D Visual, Visual Effects, Games Animation etc) several images or frames must be rendered and then 'stitched' together using your 3D modeling application (Autodesk 3D Studio Max, Autodesk Maya, Avid Softimage XSI, Maxon Cinema4D, Newtek Lightwave etc).
Rendering Features: A rendered image can be understood in terms of a number of visible features (number of faces, polygons etc). Rendering research and development has been stimulated by finding ways to simulate these efficiently, making the best use of what modeling tools are available. Giving designers the most lifelike Rendered frame or scene available. Some rendered images relate directly to particular algorithms and modeling techniques. Example Rendering Features are as follows: -
- Caustics: Reflection of light off a shiny object to produce bright highlights on another object
- Shading: How the color and brightness of a surface varies with lighting
- Shadows: The effect of obstructing light
- Reflection: Mirror-like or highly glossy reflection
- Refraction: Bending of light associated with transparency
- Motion Blur: Objects appear blurry due to high-speed motion, or the motion of the camera
- Depth of Field: Objects appear out of focus when too far in front of or behind the object in focus
- Soft Shadows: Varying darkness caused by partially obscured light sources
- Transparency: Sharp transmission of light through solid objects
- Translucency: Highly scattered transmission of light through solid objects
- Bump Mapping: A method of simulating small-scale bumpiness on surfaces
- Texture Mapping: A method of applying detail to surfaces
- Photorealistic Morphing: Photoshopping 3D renderings to appear more life like
- Fogging/Participating Medium: How light dims when passing through non clear air
- Non Photorealistic Rendering: Rendering of scenes in an artistic style, intended to look like a painting or drawing
Rendering Techniques: Many rendering algorithms are available and each software rendering application (Autodesk 3D Studio Max, Autodesk Maya, Avid Softimage XSI, Maxon Cinema4D, Newtek Lightwave, Brazil, Mental Ray, Maxwell, Vray, Gelato etc) can employ a number of different techniques to produce the final image or scene.
Tracing every ray of light in a scene is very impractical and takes very large amounts of time to render (making the design pipeline very inefficient). Even tracing a portion large enough to produce an image takes a large amount of time (if the sampling is not intelligently restricted). To make the rendering process more efficient four loose families of light transport techniques have emerged. These are rasterisation, scanline rendering, ray casting, radiosity and ray tracing. Each has its own advantage giving better more realistic rendered outputs (dependent upon project use etc). Ray tracing is by far the most realistic rendering technique as it utilizes more advanced optical simulation to obtain more realistic results, but at a speed that is dramatically slower than other techniques. CAD2 Blade RX Render Nodes can help reduce rendering times when rendering large complex ray traced scenes/images.
Most advanced software renderer's combine two or more of these techniques to obtain a fine balance between image quality and actual rendering time (like Splutter Fish's Brazil, Chaos Group's Vray and Next Generation Technologies Maxwell Render).
Scanline Rendering & Rasterisation:
A high level representation of an image necessarily contains elements in a different domain from pixels. Pixel by pixel rendering gives a very high quality image output (rendered image) but takes a considerable amount of time. If a pixel by pixel approach to rendering is impractical or too slow for your particular project then a primitive-by-primitive approach can prove to be more useful. This is called rasterization and is the rendering method used by most current graphics cards.
CAD2 Blade RX Render Nodes incorporate the very latest 64Bit Quad-Core microprocessors to allow ultra high quality pixel by pixel rendered image to become part of the standard design process. Shortening the production time line and enabling a quicker return of investment (ROI).
Rasterization is frequently faster than pixel by pixel rendering for three reasons. These are as follows: -
Large areas of the image may be empty of primitives; rasterization will ignore these areas, but pixel by pixel rendering must pass through them (wasting time).
Rasterization can improve cache coherency and reduce redundant work by taking advantage of the fact that the pixels occupied by a single primitive tend to be contiguous in the image.
Rasterization is usually the approach of choice when interactive rendering is required; however, the pixel by pixel approach can often produce higher quality images and is more versatile because it does not depend on as many assumptions about the image as rasterization.
Rasterization exists in two main forms, not only when an entire face is rendered but when the vertices of a face are all rendered and then the pixels on the face which lie between the vertices rendered using simple blending of each vertex colour to the next, this version of rasterization has overtaken the old method as it allows the graphics to flow without complicated textures (a rasterized image when used face by face tends to have a very block-like effect if not covered in complex textures; the faces aren't smooth because there is no gradual color change from one pixel to the next). Sometimes designers and modelers will use one rasterization method on some faces and the other methods for the remaining faces, thus increasing speed and not hurting the overall effect.
Ray casting is primarily used for real time simulations, such as those used in 3D computer games development and cartoon animations where detail is not important or where it is more efficient to manually fake the details in order to obtain better performance in the computational stage. This is usually the case when a large number of frames need to be animated. The resulting surfaces have a characteristic 'flat' appearance when no additional tricks are used.
Radiosity: Radiosity is a method which attempts to simulate the way in which reflected light, instead of just reflecting to another surface, also illuminates the area around it. This produces more realistic shading and seems to better capture the 'ambience' of an indoor scene. A classic example used is of the way that shadows 'hug' the corners of a room or building. This is very popular in the 3D Architectural and Visualisation industry where 100% exact representations of a interior/exterior design has to be simulated throughout the entire project.
The optical basis of the simulation is that some diffused light from a given point on a given surface is reflected in a large spectrum of directions and illuminates the area around it. The simulation technique may vary in complexity. Many renderings have a very rough estimate of radiosity, simply illuminating an entire scene very slightly with a factor known as ambiance. However, when advanced radiosity estimation is coupled with a high quality ray tracing algorithm, images may exhibit convincing realism, particularly for indoor scenes.
Our Blade RX Render Nodes offer ultimate hardware rendering performance for real time Radiosity projects and animation frames/scenes. For further information please contact our rendering specialists on +44 (0) 800 180 4801 or e-mail firstname.lastname@example.org
Ray tracing: Ray tracing is an extension of the same technique developed in scanline rendering and ray casting. Like those, it handles complicated objects well, and the objects may be described mathematically. In a final, production quality rendering of a ray traced work, multiple rays are generally shot for each pixel, and traced not just to the first object of intersection, but rather, through a number of sequential 'bounces', using known laws of optics that deal with refraction and surface roughness.
Until recently raytracing was considered to slow for real time or animation sequences of any degree of quality (automotive design/simulation, advertisement, still images etc). With the recent launch of our Blade RX Quad-Core Render Nodes, ultra high quality photo realistic raytraced images are now possible in record time, removing the typical bottlenecks normally associated with Raytrace renders. For further information please contact us on +44 (0) 800 180 4801 or e-mail email@example.com