Hi there,
I’m just trying to get displacement working properly in XSI (from ZBrush) But I can’t seem to get the mid point working right. The displacement is always pushing in or out. Has anyone here got any ideas?
Like this -
http://www.naffupdate.com/forumfiles/zbrushpain_2009-04-21_14-23-31.jpg
http://www.naffupdate.com/forumfiles/zbrushpain_2009-04-21_14-23-41.jpg
How do I figure out what to set the ‘Change range’ node to, to make it right?
any help would be great 
thanks
Pete
If you’re model isn’t too dense you might just want to look at importing it into XSI and going from there to generate your maps. I personally find zbrush to be too much voodoo for such simple things…too bad there is no vector map export either…that makes life a lot easier for sure.
What bit depth are you using? If I remember correctly float files for displacement are easier to setup in XSI that 16bit ones as the range is more predictable with the float ones.
Yes, I hate the voodoo! But I really like sculpting in ZBrush. I’m using the 16bit export. Not just the standard one (to avoid steppy artifacts). Everything seems to be working fine, except the mid level…
…knowing the alpha depth factor is helpful, but it would also be good to show a screen capture of your displacement settings coupled with your rendertree setup to assess everything you have set up.
Without seeing that and focusing only on the change range node, I guess you have to understand the change range node…which I assume you do. But just in case. The Old Range Start and End represent the range within which the white and black values can be found. Using the change range node, we are simply remapping these values so that Zbrush’s displacement syncs up in XSI.
…So if your Alpha depth factor is approx. 7.086 (as you provided), then the New Range Start and End (as a starting point) would be -3.543 and 3.543. Match the 3.543 value in the max displacement value in the PPG for Geometric Approximation > Displacement. [3.543 is half of 7.086 btw – in case you are wondering where I got that value.] By putting this as you max dipl, you should capture all the information that you created in Zbrush. You can also increase this value if you experience clipping in your model’s displacement (i.e. flat planes where the displacement end abruptly…) but you should not have to do this if you like what you achieved in Zbrush…the option is there though.
You likely know this and have it buttoned up but as I am on the topic…The other value to pay attention to in the Geometric Approximation > Displacement would be the length value as it defines the smallest triangle that can be calculated on the model…as such smaller values will enable you to get more detail…but be wary of increasing render time.
Re: your mid point question, your mid point would be at the 0 value in this range…as I understand it. This is something I have always thought but not tested all that much so if someone knows something I do not, please correct me.
What if you chose 2 as the start value and -5.086 as the min value? The new mid point be -1.543? I think so, but what effect would that have? I would definitely test this…and maybe you have…just never really had to go much further on that…might test and write back some more…I have some thoughts of controlling the mid point or playing with the mid point using a gradient to simplify setup and testing…hmm…well, give this a try or let me know if this is where you are already and are facing issues.
I am sure that all of this is echoed somewhere on zBrushcentral so definitely check out the resources there for pipeline thoughts from Zbrush to XSI…
Hey thanks!
I had trouble with it before, but it seems to be working okay now.
It’s still a little off…
But I made up a handy little compound that sorts out a few things. (pretty basic really)
The offset controls the mid point, (it would be handy if I could change the slider ranges in this compound because it goes from 0-100, it works if you type them in though)
Displace helper compound
What are your displacement settings in XSI?
What’s the resolution of your image and I take it you’re still using a 16bit depth file right? Try a higher res if you can and higher depth and see if that makes a difference.
Ahh crap, i spoke too soon. That all works for the sphere but not my model!
I don’t get it!
See how this one expands out…
Why does it have to be so hard? 
IIRC the base settings for kind of easy displacement out of z-brush are 3 channel full range 32 bit. I usually modify from the R32 settings. The displacement settings in xsi should be something like -.5 to .5 in the change range or -1 to 1
Use fine mode for displacement in the geo settings with I think a low length like .1 , sorry I don’t have it in fron of me to confirm or take screens.
I think XSI struggles with greyscale 32 bit images so you should use RGB I think thats the big one not working here
You might want to convert the file to a .map file in the end too. It’s not going to necessary help you get more details or anything…but might help on the memory and texture loading front come render time…
if you are doing 32bit displacement why don’t just plug the displacement in the displacement port, set the geommetry approximation to fine, and subd to something like 2. and that’s all?
The change range node works to remap the scale of the bump, but if it’s a 32 bit map it should just work like I say.
Yes, I have it!!
It was because I wasn’t saving a morph of the original shape in zbrush.
When I reverted to that it seems to get the mid level right!!!
It doesn’t seem to look as nice as the one in zbrush though and it has little gaps in the geometry now but at least i’m getting somewhere!!!
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