Monday, April 20, 2009

How to create artistic 3-D photo realistic images?

The Persistence of Vision Raytracer is a high-quality, totally free tool for creating stunning three-dimensional graphics. It might be useful for designers, photographers, and hobbyists, who do not mind spend some time to create real art with this amazing open-source utility. Review samples of the images, created with its help.


The Persistence of Vision Ray-Tracer creates three-dimensional, photo-realistic images using a rendering technique called ray-tracing. It reads in a text file containing information describing the objects and lighting in a scene and generates an image of that scene from the view point of a camera also described in the text file. Ray-tracing is not a fast process by any means, but it produces very high quality images with realistic reflections, shading, perspective and other effects.

What is Ray-Tracing?

Ray-tracing is a rendering technique that calculates an image of a scene by simulating the way rays of light travel in the real world. However it does its job backwards. In the real world, rays of light are emitted from a light source and illuminate objects. The light reflects off of the objects or passes through transparent objects. This reflected light hits our eyes or perhaps a camera lens. Because the vast majority of rays never hit an observer, it would take forever to trace a scene.

Ray-tracing programs like POV-Ray start with their simulated camera and trace rays backwards out into the scene. The user specifies the location of the camera, light sources, and objects as well as the surface texture properties of objects, their interiors (if transparent) and any atmospheric media such as fog, haze, or fire.
For every pixel in the final image one or more viewing rays are shot from the camera, into the scene to see if it intersects with any of the objects in the scene. These "viewing rays" originate from the viewer, represented by the camera, and pass through the viewing window (representing the final image).

Every time an object is hit, the color of the surface at that point is calculated. For this purpose rays are sent backwards to each light source to determine the amount of light coming from the source. These "shadow rays" are tested to tell whether the surface point lies in shadow or not. If the surface is reflective or transparent new rays are set up and traced in order to determine the contribution of the reflected and refracted light to the final surface color.

Special features like inter-diffuse reflection (radiosity), atmospheric effects and area lights make it necessary to shoot a lot of additional rays into the scene for every pixel.


Here are some highlights of POV-Ray’s features:
1. Easy to use scene description language.
2. Large library of stunning example scene files.
3. Standard include files that pre-define many shapes, colors and textures.
4. Very high quality output image files (up to 48-bit color).
5. 16 and 24 bit color display on many computer platforms using appropriate hardware.
6. Create landscapes using smoothed height fields.
7. Many camera types, including perspective, orthographic, fisheye, etc.
8. Spotlights, cylindrical lights and area lights for sophisticated lighting.
9. Photons for realistic, reflected and refracted, caustics. Photons also interact with media.
10. Phong and specular highlighting for more realistic-looking surfaces.
11. Inter-diffuse reflection (radiosity) for more realistic lighting.
12. Atmospheric effects like atmosphere, ground-fog and rainbow.
13. Particle media to model effects like clouds, dust, fire and steam.
14. Several image file output formats including Targa, BMP (Windows only), PNG and PPM.
15. Basic shape primitives such as ... spheres, boxes, quadrics, cylinders, cones, triangle and planes.
16. Advanced shape primitives such as ... Tori (donuts), bezier patches, height fields (mountains), blobs, quartics, smooth triangles, text, superquadrics, surfaces of revolution, prisms, polygons, lathes, fractals, isosurfaces and the parametric object.
17. Shapes can easily be combined to create new complex shapes using Constructive Solid Geometry (CSG). POV-Ray supports unions, merges, intersections and differences.
18. Objects are assigned materials called textures (a texture describes the coloring and surface properties of a shape) and interior properties such as index of refraction and particle media (formerly known as "halos").
19. Built-in color and normal patterns: Agate, Bozo, Bumps, Checker, Crackle, Dents, Granite, Gradient, Hexagon, Leopard, Mandel, Marble, Onion, Quilted, Ripples, Spotted, Spiral, Radial, Waves, Wood, Wrinkles and image file mapping. Or build your own pattern using functions.
20. Users can create their own textures or use pre-defined textures such as ... Brass, Chrome, Copper, Gold, Silver, Stone, Wood.
21. Combine textures using layering of semi-transparent textures or tiles of textures or material map files.
22. Display preview of image while rendering (not available on all platforms).
23. Halt and save a render part way through, and continue rendering the halted partial render later.




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