Displacement Problem

[Philw]

I am having a problem with my 1st use of displacement. I have a rug I created and made sure the geometry is on the floor, but when i render the scene the rug appears to be floating.

I do not know what I am doing wrong, any help?

V-Ray 2.00.02
SKU 2015

[omiKron]

Try to invert the bump, or move the mesh lower. I had the same problem with a grass mesh but after inverting the bitmap it worked.

[panixia]

i'd rather tried to avoid displacing a completely flat mesh (so that all normals are parallel on z) try to extrude down the bounding borders and maybe chamfer it a bit.. that way the border vertices should be moved on xy rather than z..
also you could try to play a bit with shift/water level to fine-tune this

edit - just to clarify

i added this example (i used fredo tools -> "construct face normals") so you can see what happens.. as far as i can tell, actually displacements uses normals to move geometry.. so vray it's doing exactly what expected to do.. you need proper geometry to get proper displacement.

[Philw]

I've tried both methods,

Inverting the map did nothing for it, and changing the water level did not change a thing. Making a box with chamfer edges seem to work (or at least hide the fact that it floating?). I'll keep instigating and if I find an answer I' post it here.

Thanks for the help

[panixia]

@philw said:

Making a box with chamfer edges seem to work (or at least hide the fact that it floating?). I'll keep instigating and if I find an answer I' post it here.

there is nothing to hide, as stated, it is not floating at all because border faces are extruded sideway, not upwards.. which other answers are you looking for?

[jiminy-billy-bob]

You are looking for the "shift" input box. Put a negative value in there, it should do the trick.

[panixia]

yeah for sure, i was also suggesting shift for fine-tune the fur lengt, but IMHO actually that alone is not enough. if you don't model and chamfer properly the "tickness" of the rug (this is what happens in real life with that sort of rugs) you maybe could also take it back on ground but the border will look unrealistic because it's still 2d..

[Philw]

Thanks for the reply,it is all good input.

I am new to V-ray and I keep looking for information on the program, but to date i have not found something that explains what each check/pick box controls. Some items have pop up boxes that tells you about that function when you hover over it, other do not. Since I am learning this on my own is there somewhere I can get information on all the items and what they do?

Is displacement the best way to do a shag rug or are there other ways to get a nicer looking shag rug in V Ray?

[panixia]

here vray manuals http://docs.chaosgroup.com/display/VRAY2SKETCHUP/V-Ray+2.0+for+SketchUp+Help# #

for the rug you should also consider to use make fur plugin and maybe create a proxy.. i think that way should render faster than displacement

[Philw]

Thanks