Wow, this is a sleepy little backwater of a sub-forum.
I've just been reading about Saginaw in the US, made famous when Paul Simon took 4 days to hitchhike out of it so he could 'find America'- this must be DCad's 'Saginaw'!
I've gone on about how useful Sketchup is as a 3D display tool before - I don't use it to build 3D models (even small editing endeavours are painful to me in SKP compared to DCad) but it is very good at displaying and moving around in large files very smoothly. The 'real time' shadows it produces are also indispensable now for me as we now have to produce detailed shadow maps on all commercial & condominium projects in order to get environmental approval.
And it's free! (Sketchup Make)
It's rendering ability is better than DCad but it is still not great, so I recently bought a rendering plugin - Shaderlight - for it which produces stunning results for the money.
As I mentioned, Sketchup is free but I paid about $300 for a licensed copy of Shaderlight (still way cheaper than other photo-realistic renderers) and because it's a plugin for SKP you can take advantage of their massive selection of 3D models which I use to populate my 3d models.
The attached render started as a DCad drawing (724kb size) which I exported to SKP - I geographically placed it in position in Google Earth so the shadows would be correct (my client is very worried about not getting sun in the living rooms, in Thailand sun is bad, very bad).
I then furnished the entire house, added trees and potplants, even wine bottles & a coffee machine in the kitchen. This expanded the SKP file from 440kb (a bit smaller than the DCad file) to about 95mb and it is still easy and smooth to manipulate.
The 'camera' controls are much more intuitive than DCad's controls (ask Doctor Phil what he thinks about that!) with typical 'real camera' controls like focal length. There is a 'walk around' option that allows you to pull yourself through the house, bumping into walls and furniture (but not going through them) you do tend to 'jump up' onto the lower furniture though but it happily 'walks' you up and down stairs.
Shaderlight plugin lets you place all kinds of lights including 'IES' lights which allow you to download light maps from the bulb manufacturer so you can place the actual bulb you'll be buying from your local shops. It's transparency and reflective material options are impressive, I've finally mastered how to get underwater lights in a swimming pool to display the way I want (hint, you need to make the pool tile highly reflective and bump up the wattage of the bulbs massively).
They even get the refractive property of water right, making the pool look very shallow, just like in real.
This render at 3600 x 2025 size (& best possible quality) took about 28 hours to generate, although you can get very usable images at 1800 x 1012 pixels after a couple of hours - before that they are very grainy.
With this type of rendering ability within our grasp, I don't see why DCad should spend any time trying to improve its rendering beyond 'functional', that is, good enough to view the model while you are building it.