I gave a try using KT, + KT free trees, instancing them around the model.
background fit image + distance blue light ( to simulate blues shadows)
that is all
4 min 37 sec!

4min37secKT.jpg

brighter.jpg

Looks good! Maybe add some line work to the concrete sidewalk (control joints)to 'land' the building and also to direct your eye to the building.

Remember that you also need to adjust the camera exposure, as you would in the real world.
If you only adjust the intensity of the light sources you often end up with burned out areas.

I find that the VfSU default is set up for exterior, so when I do interior shots I need to adjust the exposure.

IrfanView and XnView are working with this on a 32 bit - try and see if it works for You.

Thats great. Thanks for the help.

@thomthom said:

Sharper? Not sure sure what you mean here. ❓

It may be hard to tell from the posted pictures what I mean. It's ok. I think my main problem was the lack of light in the scene. I've added some more light and it's brightened that backwall up.

Thanks