Once you have modeled, refined, and positioned your 3D models, you are ready to produce a photorealistic image.
We report here steps that you could follow to produce images more efficiently.
1) Set the camera position and the angle of view.
2) Assign simple materials, for example materials whose components can be a "plain" color source shader, a reflection shader set to "matte", "plastic" or "metal" and no displacement or transparency.
3) Position a few lights and set their intensities. Most scenes only require a simple set of lights, an ambient light with a low intensity and a single distant light. The distant light is likely to be positioned at 45 degrees to the camera viewing line. As an alternative to the distant light, a spotlight may be used. By positioning the spot light carefully, the objects being rendered can be made to stand out from the background. At this stage shadows should not be turned on. A recommended lighting set up is an ambient light with an intensity of 0.2 and a distant light with an intensity of 1, positioned appropriately for the relative positions of the camera and the object.
4) Use the Preview rendering for this stage.
5) Assign definitive materials. Select a type of material applicable to each object. Plain materials are appropriate for most objects. If more complex materials are selected, like blue marble, it is likely that the parameters for the material will need to be adjusted for the particular object to which they are attached. The scale parameter of such shaders allows the size of the visual appearance of the shader to be adjusted to suit the size of the object to which the shader is attached.
The three simplest reflectance shaders are matte, plastic and metal. Matte is used for materials that do not have polished or glossy surface finishes, like paper and matte-painted walls. The plastic shader is applicable to materials that are glossy and have sharp highlights, like plastic objects, varnished wood, gloss-painted surfaces and glazed ceramic materials. The highlights on plastic materials will `take on' the color of the lights being reflected, normally a white color. The Phong reflectance shader is similar in effect to plastic. The metal shader may be used on metallic objects like machined mechanical parts. The material will have sharp highlights like plastic, but they will be a lighter shade of the base color, rather than the light's color. Most objects do not require materials that use ray-tracing reflection shaders, because few real-world materials have mirror-like reflections. Many materials can be simulated using the plastic and simple metal materials, which are faster than the ray-tracing materials. The chrome 2D reflectance shader, which simulates a simplified reflective surface, can be used as a simple alternative to the ray-tracing reflection shaders.
Only use shaders that use ray-tracing, i.e. mirror, glass, dielectric and conductor if necessary. The calculation time of these shaders may be reduced significantly if the mirror factor parameter of the shader is set to be 0. If this is done, then no ray-tracing will take place, increasing the performance and reducing the memory requirement.
There are two ways of rendering transparent objects, either through ray-tracing reflectance shaders or transparency shaders. Ray-tracing can simulate the complex refractions, or bending, of light as it passes through objects. For flat or thin transparent objects, like glass in windows where there is little refraction, transparency shaders are much more efficient than ray-tracing. The plain transparency shader gives materials a uniform transparency, and has as a parameter a color specifying the amount of transparency.
If the components of the color are set to 0.3, then the material will be two-thirds transparent. If the components are set to 0.9, then the material will be nearly opaque. By setting the color parameter to be a color, like red, the material will simulate colored glass.
Displacement shaders can simulate changes to the smoothness of a surface's finish. The rough displacement shader may be used for 'natural' bumpy surfaces like stone, cast metal and worn wood. Other displacement shaders like wrapped dimple can simulate manufactured surfaces, where a regular pattern appears across a surface.
6) Adjust shadows. The shadow resolution may need to be adjusted depending on the detail contained within the object and the overall size of the object. Some images require additional fill lights to lighten the shadows cast from the main light. A distant light positioned at an angle to the main light will accomplish this.
7) Render the final image. For the final image generation you must select an appropriate image resolution. The final image resolution and aspect ratio should be selected appropriately for the final output device. If the image is to be displayed on a computer screen, then the resolution should match the resolution of the display, for example 1024 by 768 pixels. If the image is to be output onto transparency film, by a film recorder, typical resolutions are 2048 by 1365 or 4096 by 2731 pixels. The quality of shadows is partly dependent on the resolution of the shadow map, and also the resolution of the image. For higher image resolutions the shadow map resolutions may also have to be changed appropriately. For the maximum image quality the Scanline full rendering mode should be used. If shader aliasing occurs then the Raytrace full rendering mode may be used, however this will significantly increase rendering times.