Hi Tarik,
I couldn't really follow your question:
I'm wondering why when I view a .pic image I've created in HDRShop, the pixel
values aren't the same as when I generate a text file of their colours using
vwrays.
I first read this as if you had created the .pic in HDRShop, which didn't make sense. I assume now you are only viewing it with HDRShop. What do you mean that the pixel values aren't the same? The same as what? The same as eachother? You are expecting them all to be the same? ??
I wnat a green box's surface reflectances in the pic file so I do
./vwrays.exe -fd greenbox.pic | rtrace -fda `vwrays -d greenbox.pic`
-ovm `if(s='green_plastic')` testroom.oct | grep "green_plastic" > rays.txt
Ignoring the `if(s='green_plastic')` nonsense, which I'm hoping doesn't do anything, this command might give you the luminance at each visible point on the green surface, but not its reflectance. If you want the reflectance, just look at the Radiance scene file. It's right there in the definition of "green_plastic".
-Greg