I have this model that has an issue with scale. I have a loft that I converted to an edit poly and when I add a vdisplacementmod with amount at 6" the surface is flat. If I go to 6’ it works, kind of. The whole scene is in inches and everything else is correct. What would cause this?
If the problem is scale, just create a box 1,1,1", convert to editable poly and atach your model, after delete the box, the model it will assume the scale of the box. That’s good to uvwmap’s issues also. 
there is a utilility to scale your scene you correct the units. this also fixes for example the UVW sizes and such.
tool can be found in the utility panel > rescale world units
Units
Ugh… neither worked! Can someone take a look at this? It is driving my crazy.
Units
Anybody? I have a deadline.
Well, I don’t have vray for max9 yet (were still using 8 ) tho I do have max9 installed, so I looked at the object and the scale seemed fine, at least I couldn’t notice anything wrong with it when I applied similar modifiers that took input based on unit scale. The scale is all at 100, etc. so I’m not sure what the exact issue is.
Units
Thanks for looking. When I apply a vray displacement of, lets say, 3" it is flat. When I add a displacement of 3’ the element is flat, but floats above it’s placement. This has happened before and I though I fixed it. This is the same file I originally had issues with, but this is a new element. The element is a loft that I do some cookie cutting to and polyboost pushing and pulling.
Any clue?
Units
Here is displaced at 2’
Here is 2"
Just a shot in the dark, make your shift be the negative value of your amount
so if your amount is 3" make your shift -3", see if that fixes it.
Just having a look now Bobby, will get back to you shortly.
Ah.. kinda need your displacement map for accurate testing as well.
<edit> NM find it on a site somewhere.
Units
Thanks
Ok, the way I think its working out as its a color map. You should ideally convert it to B&W first. Then you can kinda see why its shfting up.
If you set an amount of 3inches, that 3inches is for the maxium displacement which would be any white in your displacement map.
But that map has mostly middle gray so its wont displace the full 3inches, and since there isnt really any black the whole mesh will be lifting up. So without editing the map in ps to change the color abit you need to adjust your displacement accordingly. Using negative shift amounts.
Here is a PS’d black and white version of the grass map. Its not perfect but should be alot better than the one your currently using for displacement. Notice the bits that shouldnt be displaced are alot closer to black and the tips of the grass are closer to white. This will mean a more accurate displacement for you. Also turn off the bitmap blur and filtering to also up the accuracy and quality.
http://www.apex.net.au/~daforce/vray/shortgrass\_1\_DISP.rar
Units
That makes sense, but it worked great before. I’ll try it, thanks.
Maybe try 3D displacement?
Anyway, its not really worth wasting time on. To get the height you want, just make a small box the same height as what you want the grass at then use render region and adjusting the displacment amount until its the right height. Should only take a few mins.
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it was the darn displacement map! Thanks for the help.
yep thats what i figured would be the larger part of the problem.
Good to see you got it sorted 
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I could sware I got great results using the same images in a previous project. Thanks for the help.
Anytime 8)
woot! Glad this got solved.