In the Links below I used an HDRI Image to reveal the background so it looked like the characters are in the scene. I use a  Very Large 380 Degree pano Pano that is or about 768x 2200. I will add black on the bottom to the tune of an extra 800 pixels plus or minus to suit the image. The black throws no light. If you use any other colors, thats the color your light will be hued. You can Adjust the Blueish hue most HDRIs throw under your light tab/sky dome color. I always use a grayish color that way the models in the scene still look fairly normal. I would tell more, but I am at work can't open my Vue and tell precise facts. Also use the bottons to adjust the HDRI up or down---right or left and that will take care of the black bottom unless yout terrain and models do it for you.
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Oh yes, and basically because I am using a High Res Photo and not an High Dynamic Photo it is considered an LDRI.

I would rather be Politically Incorrect,
Then have Politically Correct-Incorrectness!!!