Bellow is a small list of things that I consider important when doing architectural visualization (or any other subject, as long as it is supposed to be a photorealistic rendering), and from what I see in the image galeries, a lot of people don’t seem to care about.
1) 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. Bellow are a few images that illustrate better what I’m trying to say.
(click on an image to view a higher resolution one)
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.
2) Don’t 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. This is one of the first things that you learn at art school. 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.
3) 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 (it will also increase the rendering times though…)
4) 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. The photo below has been taken at mid day; take a look at it to see how crisp/soft is the shadow.
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.
Hope these were helpful; feel free to add to the list if you wish.