Checking and refining the 3D model

It doesn't matter if a client provides a 3D model or you use a model you created, you still need to check whether there is any bad geometry and, most importantly of all, the level of detail.

The level of detail

The level of detail that is required depends on two aspects. The first aspect you need to take into consideration is how close the 3D model is to the camera? Something that will be in the foreground will need to be more detailed than another 3D model that is, perhaps, in the back of the room hidden by a curtain. It sounds really basic and like a simple tip, but the most efficient practices tend to be simpler.

You will have several benefits if you take this first practice into consideration. You won't have to spend time modeling details that are not visible or have no visual impact on the final render. Since you'll have fewer polygons, the scen51e will be lighter and faster to render. However, what is the second aspect that constrains the level of detail...