Here’s a small list of things that I consider important when doing photorealistic visualization (especially architectural ones).
Tip 1 – Do not use 100% black or 100% white colors
The explanation for this is very simple. To ‘show’ an object’s volume you need to have highlighted areas, shaded areas and mid tones. If a material that is assigned to a 3d model has a 100% black color in the diffuse channel, there will be no visible difference between the mid tones and the shaded areas and it will make your model look flat. Same thing goes for 100% white objects, only this time there will be no significant difference between light areas and mid tones.
Tip 2 – Use chamfered edges, especially in close-ups
In real life there’s no such thing as ‘razor sharp’ edges. Take a look at the objects around you and notice that every edge is more or less rounded. Although in the cad files provided by the architects you will never see this, keep it in mind when building the 3d model.
Chamfered edges not only will make your 3d models look more real, but also may catch specular highlights which will give more depth to the rendering.
Tip 3 – Always use area shadows
If you are doing an exterior rendering, you need to control the sharpness of the shadow, depending on the time of the day. In the morning the shadow is very soft, and it gets sharper and sharper until mid-day; after that moment, it softens again until night. Even at mid-day the shadow is not 100% sharp though so you still need to use area shadow, just adjust the parameter to make it less soft.
Same goes for artificial lighting. Some fixtures cast a subtle shadow, while others (like spotlights) cast a sharper one, but again you should always use area shadows and adjust the parameters accordingly.
Tip 4 – Blur parameter from 1 to 0.1
By default, the blur parameter in the bitmap’s coordinates rollout is set to 1. This causes the textures to look blurred, especially if they are looked at from an angle. By setting this parameter to 0.1, will make the texture look sharper and therefore more real
Hint: This will also increase the rendering times though
Hope these were helpful!