Displacement problem: greyscale profile for maps?

[simmsimaging]

Hey all -
I'm trying to displace something but I'm finding that 50% grey is actually displacing *in/down* for some reason. I have the displacement value and shift at .5 / -.5 and in Photoshop I made a map that is has large areas of 50% grey. I am using LWF and have input/output gamma set in in Max at 2.2

I have tried saving the 16bit greyscale map out of Photoshop with my usual profile (20%dot gain), and then again with Gamma 2.2 greyscale profile, and I have loaded both in using all 3 options in the max bitmap loader, and also using hte Vraybitmap filter. I cannot figure out why 50% grey is still displacing at all.

What is the correct profile to use out of photoshop, and if using gamma 2.2 workflow what should the bitmap be set at on loading?

Thanks for any help - I'm on a tight timeline with this one!

b

[simmsimaging]

I think actually there may be something going on in Vray.

I tried creating a VrayColour at 50% grey and even that displaces in slightly. I have tried 32bit, 16bit and 8bit images as well. Is it possible there is a bug with SP3 and gamma that is affecting the displacement modifier?

Thanks
b

[percydaman]

I just did a test. An plane set to 1' displacement with a vraycolor at pure white, displaced 1'. A plane set to 1' displacement with a vraycolor at 50% gray, displaced 6". Would seem to confirm your conclusion, though I always thought that vray set its 0' height at black not 50% gray.

[vlado]

If you want the middle grey to be no displacement, the shift value should be the negative half of your displacement amount. So if your displacement amount is 0.5, the shift should be -0.25

Best regarsd,
Vlado

[simmsimaging]

Wow. I really am an idiot. Thanks Vlado, and thanks for looking into it Percy.



b