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MaxToA How to do negative Displacement?

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Message 1 of 6
lemoinemarc
1410 Views, 5 Replies

MaxToA How to do negative Displacement?

Hi! I'm trying to make a negative displacement. It's a seamless line arrangement that I want it to be carved 1inch in the model. with Vray i'm able to give a value of -1 to the white lines and it carves it on the box. I followed the Arnold tutorial on Displacement, even thought it says we can, i'm not able to give negative value. Either in physical material or in Arnold properties modifier..

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Message 2 of 6
lee_griggs
in reply to: lemoinemarc

You could try using a Complement shader to invert the bitmap.

366-complement.jpg

>I followed the Arnold tutorial on Displacement, even thought it says we can, i'm not able to give negative value.

Where does it say that?

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 3 of 6
lemoinemarc
in reply to: lemoinemarc

Thanks for the answer @Lee Griggs unfortunately I already tried to invert the bitmap but it displaces the groove outside instead of carve it inside..

here's what I mean:

369-expl-large.jpg

Here's What I need: linked autocad file + vraydisp mod set at -1'' (need some tweaking..):

370-h.jpg

Ps.: and for the negative value I tought I saw, I misread: ''...This is because integer formats do not support negative pixel values, which are used by floating-point displacement maps.''

Message 4 of 6
madsd
in reply to: lemoinemarc

This is easy to do.

All we need to do first is to understand ranges, especially ranges in positive space and ranges in negative space.

If we pipe a map to a displacement, it will always be going from 0-1 in the range typically, but we want this range to be set to a new range, because we CARVE, this means we got a floor and a roof.

The old roof was 1 and the floor was 0.

We use a range node to convert the space into a useful range when carving and the range we want to output is from -1 to 0, meanin displacement will only go on the negative while leaving the roof untouched.

So source into a converter, and then add a Color Correct node to flip the image around, so that stuff that needs to carve is BLACK, and stuff you dont want to move is WHITE.

See a functional carve here.

Attached a max 2016 file with working carving, and a bitmap, just reload the bitmap back in and it will work.carve-displacement.zip

640-werwer.gif

643-cc.jpg

641-2017-12-25-13-17-21.jpg

642-2017-12-25-13-17-52.jpg

Message 5 of 6
pproestos
in reply to: lemoinemarc

Holy s.... Mads I archive any answer you give man...

you rock...

Message 6 of 6
lemoinemarc
in reply to: madsd

Thank you, it works! I am very impress with your solution! I will add for the people who use linked dwg geometry, that you have to add a Quadify Mesh modifier to be able to change the heights. 🙂

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