Re: HDRI shoot: grey color sphere question, what kind of gray?

["Tim Leydecker" <BauerOink(at)gmx.de>]

18% grey would be great to have as a spraypaint but you should
be able to "register" any color you find pleasing by doing a couple
of exposures (on the filmstock used) with your painted ball PLUS
an 18%grey card. If you use an analogue camera and/or have some
sort of scanning process involved that´s a good start to find out the
offset introduced through the lab process by using Photoshop´s
colorpicker and comparing the "IS" color with the "should be" color,
then getting a factor for your painted ball, "IS" like 24% grey but
"looks like" 36% grey with a slight magenta tint, which should give
you enough info to either "up your tonemapping/exposure" 1/2 stop,
and adding a slight magenta tint or just set the light´s intensity to 1.5
with a slight magenta tint. So much for the theory. I´d actually add
a flat white sheet as well and fiddle a bit with whitebalance on/off
to check how the CC chip/modes of the camera behave in general.

There´s a pretty nice tutorial (I think fpr combustion) somewhere
on the web, showing how to use standard colorcharts to CC and match
footage into various looks. I´ve no link unfortunately but it was quite complete...

Cheers

tim

P.S: In case you lack a shop where you can get "dulling" and colorcharts,
you can at least get some sort of shatter by using hairspray (not the glossy one...)


----- Original Message ----- 
From: "Francois Lord" <francoislord(at)gmail.com>
To: <XSI(at)Softimage.COM>
Sent: Tuesday, January 02, 2007 4:53 PM
Subject: Re: HDRI shoot: grey color sphere question, what kind of gray?


> I didn't try it, but I heard using a "submarine paint" from a scaled model shop. 
> Apparently, it's close to 18% gray and there is virtually no hilight. Instead of 
> styrofoam, try to find a big plastic christmas ball.
>
> Rob Wuijster wrote:
> > Hi all,
> >
> > I have to do a HDRI shoot next week, and have to create myself a new gray "color" 
> > sphere again for lighting purposes (The last one didn't survive a friendly 
> > soccermatch.....animators these days....)
> > It has to be a neutral gray, but does anyone has defined colors for this, so I can 
> > just get a spraycan at the shop and color a white stryrofoam for my shoot.
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