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Rendering CGI
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| What is it? |
Simply, rendering is the process of generating an image from a model. Rendering is a computer processing intensive process in which the model combined with data about texture, lighting, and shading is outputed to a final picture. There are many different rendering algorithms and engines available, however, the two main techniques are scanline and ray casting which are covered in this section. Rendering takes a lot of time so a more efficient algorithm is always being sought after. |
| Visible Features | ||
A rendered image is a combination of visible features. The following are just some features which are produced in the rendering process.
From the images below in the images section you can see these visible features. |
| Scanline Rendering |
The way this rendering algorithm works is exactly how its named and is the preferred method of generating computer graphics in film. This type of rendering is the most widely used and is implemented in most software packages. Scanline rendering works on a row-by-row basis. That is, all the polygons are first sorted by their top y coordinates and then each row of the image is rendered where the scanline (current row) meets the polygon mesh. The scanline will iterate through each pixel of the polygon mesh and compute its visible features to be displayed in the final image. Assigning these colors to these output pixels is a process called rasterization. Scanline rendering offers a number of advantages including realtime rendering and speed. |
| Ray Casting |
This rendering process, althought not as widely used as scanline, is also efficient and can produce photorealistic results. Ray casting works by following rays of light from the eye of the observer to a light source. The main concept behind ray casting is that it shoots rays of light to each pixel and finds the closest object that blocks it path. Then using the material properties of the object and the effects of light, shading of the object can be determined. Since different colors and textures absorb, reflect, and refract light differently, each pixel's visible features are accurately calculated. Ray casting is a newer technology than scanline rendering and is adopted in many of the high end software packages. However, its algorithms are complex and render time can be lengthy. For full feature films, render time can take too long to meet production deadlines. However, for high intensity photorealistic visual effects, ray casting may be the method of choice. |
 Ray casting rendering |
| Images | ||
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