Backgrounds, distant objects, and skydomes

MKDAWUSS

What's the trick to making these convincing? More often than not in 3D world (not just DAZ world - I notice this is in games too), I notice where the world ends and the background begins, and sometimes it's a bit glaring. What's the trick to getting the objects to blend better with the background? The less that's faked - or less noticeably faked - the better. I've often resorted to positioning renders where the wall or floor cover the entire view, or the shot is low pointing up just enough (outdoors, some windows), or it's a shot where the backdrop allows for a off-camera drop-off between the figure and the backdrop (hills, mountains).

FSMCDesigns

enable depth of field (DOF) in the camera which blurs the background a bit

Chezjuan

If you use Iray you can use HDRIs. They provide good backgrounds (including ground in most cases) and there is not really an issue with positioning like with a backdrop on a plane or using the "environment" tab to insert an image.

1. Turn on Draw Dome in Render Settings -> Environment
2. Click the image in Environment Map and select the .hdr file

Considerations for HDRIs:

• They contain lighting information so you can rotate them to change how the light they produce hits your scene. The background moves when you do this as well, so if you are trying for a specific view you may need to put up with the lighing being not where you want it.
• Speaking of lighting, you want to look at supplementing the light from the HDRI so the skin tones of the figures looks natural. That goes a long way in selling the illusion.
• Since they are full 360 degree domes, you need higher resolution than you would think. I usually reneder at quad HD and use 8k or 16k HDRIs for shots where the background is a big part of the end result, but go lower if I am using DOF or it is an incidental view, like something out a window off to the side.
• Change Dome Mode to finite sphere and, if necessary, adjust the dome radius and/or scale multiplier so the image looks right (doesn't noticably curve straight lines, etc.). 
• Turn on draw ground if it is an outdoor scene where the character or objects will be seen interacting with it. If Ground Position Mode is set to auto, it will position itself under the lowest object in the scene.