How useful are they to match the lighting of the real world? Do you use one often when compositing?
Do you mean the actual object or those pictures?
the actual ball, used in conjunction with hdrshop I believe it’s called. Using the ball to create a world by which the scene is lit with.
Honestly, I don’t think it would work that well, because I don’t think it gets the right part of the picture, and I think that you’d get finger prints all over it.
The process is essential but:
Chrome balls are useful, but it’s teadious to do, do you have a digital camera that you can bracketed exposures on, there’s loads of tutorials and search BA lot’s been said here. If you go for a chrome ball, then get a couple of high polished hollow ball bearings a 2" and a 4", not those xmas dec’s or garden stuff.
But even then it’s a PITA to paint yourself and tripod out of a lot of images before you even get to making the HDR from multiple images of a 360deg scene with bracketed exposures and getting them to line up.
What I’d suggest though is getting a nodal pan head for your tripod and forget the chrome ball stuff, then get some camera automation software to control your exposure bracketing and shoot remote.
…or a 180 degree fisheye lens on an SLR…
Chrome balls, as I used them in photography, were not used to determine “what is where in the surroundings,” but rather to allow measurement of the light sources. By examining the reflections in the ball(s), and doing a little rough math, you can estimate where the light is coming from, what color it is and how intense it is.
An “18% gray ball,” like a white-target or any other object of precisely known color, is valuable in reference photographs. Because you know what the characteristics of the object are, you can evaluate the image that you have just taken of it. (The “18%” gray value is a number that’s been chosen to take into account the gamma characteristics of photographic film.)
I have actually been known to stick “a neutral gray digital ball” into a CG shot when I am trying to (digitally) light it, especially if I have done the same thing with reference photos, as I usually try to do. (This “digital ball” is 50% gray because the CG simulated environment is gamma-free.) It gives me an easy visual reference. If you stare at a single shot for a long time, trying to tweak it, then go on to the next one etc, then come back to the first, an unwanted color-cast or inconsistency can slip into your work.