is it even possible? having only one map channel it’s a massive limitation, I’m sure support for more channels has been wished before. can’t remember if I’ve read an answer though.
But you can use different mapping channels - I do it all the time, you just need to run it through the material editor.
You can put 2 bitmaps into a mix, give them completley different mapping channels and have the mix used by your displacement, controlled by a third mapping channel.
The displacement can only read one master mapping channel, but within that you can have as many as you want.
How would you go about using more than one mapping channel within the displacement anyway?
say I have a big plane and I want to displace only some parts of it with a tileable map. this tileable map is on channel 1 which is a 200x200 cm square, then I need to mask the plane where I don’t want it to be displaced, and blend and fade my tileable map in it. this second map/mask is on channel 2 which fits my plane and it’s about 20000x20000 cm.
can be easily done with 3d displacement (which support different channels), but not with 2d. which is unfortunate, 2d displacement uses way less memory and it’s perfect for mapping flat and big surfaces.
Did you read my post?
It can be done and i’ve used it on the last 3 jobs i’ve done, as well as on the grass I posted about a while ago. Just use a mix.
can be easily done with 3d displacement (which support different channels)
Could you explain how you would do this? I was trying this weekend to use displacement to make a casino die (to impress the dots) but I could not figure out how to assign a different bitmap to each matid in the displacement modifier. How would you go about that?
In the end I made unwrapped the die and did it with a single map, but it would have been easier the other way 
Thanks in advance,
b
I wonder if you read mine.
of course I’d use a mix, in fact I do and it’s casual when using 3d displacement. on the other hand, and this is what my posts are about, 2d displacement does not support multiple map channels.
well, this is a bit different from what I described above. in my case I use a mask with a bitmap for one uvw mod channel, and the actual mask for another one. the bitmap tiles over a flat surface, and it’s masked by a b&w map which is painted on the whole object.
in your case I’d unwrap and paint as you did. maybe you can use a composite map and 3d disp but I’m not sure it would work, and sounds overcomplicated, while unwrapping it’s pretty straightforward.
Okay thanks - for a minute I thought their might be a magic bullet in there for me
b
I’m pretty sure i’ve done it with 2d displacement though… I’ll do some tests now.
edit: damn. I’ve done this before and because it looked pretty good, assumed it was working. Tiling would work for an alternative, I guess.
I did some tests too after reading this thread http://www.chaosgroup.com/forums/vbulletin/showthread.php?t=41521 however I came to the conclusion that for it to work as anticipated we would need more than 1 map channel to work in 2d displacement. Cubiclegangster, your results indeed looked excellent, I would have been tricked into thinking it was working too!
There is no way to effectively use 2 different mapping sizes/channels for 2D displacement. Even when trying to adapt the smaller or larger map with tiling factors. Somehow this has to do with the internal precision used for the largest mapping. When using tiling for the larger image somehow influences the smaller mapped (mostly the displacement) image too…very weird.
So again: I also vote for support for more texture channels or at least an extra mask slot with a seperate texture channel inside the modifier !!!
Maplayers (which is a very nice tool BTW) makes no difference !!
i’ve spent all weekend trying the method cubicleganster detailed in his grass post, and came to the conclusion there’s absolutely no support for more than one mapping channel - as trick noted, the size of any secondary maps with different matid’s seems to be set by the channel specified in the vraydisplacement mod and that channel’s corresponding uv map. tiling, via either the uv map, or the map itself, makes no difference.
so yeah, right now - 3d displacement’s the only way to go for some multi-channel displacement orgy goodness
The 2d displacement cannot be made to support more than 1 mapping channel. If you want to have more than 1 mapping channel, you need to use 3d displacement.
Best regards,
Vlado
Does this also mean that the tiling factor inside the bitmap-map can not be supported ? This would make it somewhat possible to use masks for larger areas. As it is now tiling a mask just results in scaling the mask INSIDE the boundaries for the mapping that is used for the displacement.
Unfortunately this cannot be supported either. It is a limitation of the assumptions made in advance by the 2d displacement mapping algorithm.
Best regards,
Vlado
So the extra mask slot would be impossible too because of this ?
It is not impossible, but it will make the rendering quite a bit slower…
Best regards,
Vlado
Sorry to bump this Vlado but since your 2008 answer this cannot be implemented in the future of Vray?