I can't rememberwho told me this but..
Keeping things in the center isnt always the best course t follow in design. Sometimes having assymmetry is good. Try to move your render offcenter and to compensate, brighten the empty space's colors or create a fade gradient. also, try to keep a balanced color swatch.
Predominant colors in your render should appear also in your background to keep a sense of unity. The colors should also be faded/washed out a bit so as not to distract.