[Mihai]

Regarding the mystery on how to get vdm to work from Zbrush in Maxwell, I found this post in the C4D forum on CGTalk where they say they couldn't get the tangent test map to work in C4D either, but they do suggest some settings to make maps work exported from Zbrush and used in C4D in tangent space.

Could anyone using C4D, please make a test using your own sculpt, not the test map, and use the settings suggested by TBLebowsky in this thread:

http://forums.cgsociety.org/showpost.ph ... stcount=15

Since C4D uses the same coordinate system, the settings he suggests should work fine in Maxwell as well. Make sure you export the map as 32bit from Zbrush. Since the map will be 32bits, you just need to set the displacement in Maxwell to Relative tangent - zero black, and leave Scale to 1.

[Polyxo]

Hi Mihai,
I asked Thomas Roussel of Pixologic (certainly 6 weeks ago already) to contact you.
He was very open in any sort of supporting Zbrush better; he also stated that he sent you an Email.
So you didn't get anything? I was really hoping that a fix could still make it into 2.7...

[JDHill]

Since C4D uses the same coordinate system, the settings he suggests should work fine in Maxwell as well.

Actually, Maxwell X & Z are swapped with respect to Cinema:

Code: Select all

      Cinema                    Maxwell

      | Y                       | Y
      |                         |
      |________ Z               |________ X
       \                         \
        \                         \
         \ X                       \ Z
 

I don't have Zbrush, so I can't try creating a map from scratch for you, but the ear map he provided does render correctly in Cinema (with some fiddling, and inconsistently, even then -- about one in ten tries renders without huge artifacts), but not in Maxwell.

• Cinema (R13)

• 

• Maxwell

• 

I'm certainly no kind of authority on vector displacement, though, so it may be that I've missed the point completely...I hope the information is helpful, anyway.

[Mihai]

Well just trying to understand why tangent maps from Zbrush do render correctly in C4D, but not that tangent test map. Maybe there is something wrong with it for the particular axis C4D/Maxwell need. I am talking with Thomas from Zbrush as well, just wanted to see if in fact your own tangent maps saved in 32b worked correctly.

Jeremy, I suppose one should export these maps from Zbrush using the flip axes switches that Maxwell needs, not in C4Ds coordinate system......

[JDHill]

I assume so. The Cinema coordinate system is apparently indicated in Zbrush using the magic number 3 (going by what was written in the post you linked), so perhaps there is another which would work for Maxwell.

[Mihai]

Could anyone with C4D and Zbrush please make a simple test:

Draw this shape in Zbrush:



Then export with the settings described in the CG Talk post above, so flipandswitch set to 3, and export as 32b tiff, relative tangent.

Open the resulting map and compare the R,G,B channels of that map to the map extracted from Mudbox which you can find here:
https://www.dropbox.com/s/gli6hpjc4bdo1 ... Mudbox.tif

The export probably won't look the same since as Jeremy mentioned, X and Z axis are switched between C4D and Maxwell Studio. The point is exporting a map from Zbrush where the RGB channels look the same between the Mudbox file and the Zbrush file.

The Mudbox file renders correctly in Studio, with displacement set to relative tangent, 0 black:



In the tif, the Red channel should look black (although it really isn't there is a bit of info there), the Green channel should be brighest, and the Blue channel should be a little less bright than Green channel.

Is there an axis system in Zbrush? I mean can you see in which axis you are painting? In that case try to match the axis you see in the Mudbox screenshot. So the spike goes in the negative Z direction.

[Polyxo]

On this bit:

Is there an axis system in Zbrush? I mean can you see in which axis you are painting? In that case try to match the axis you see in the Mudbox screenshot. So the spike goes in the negative Z direction.

From the Zbrush Online-Documentation:

Axis - the slider adjusts the length of the axes. The axes are displayed as Red for the X axis, Green for the Y axis and Blue for the Z axis. When your model is facing forwards (towards the camera or you, the viewer) with a rotation of 0,0,0, the X axis will be to the left, the Y will be up and the Z axis towards you. Set the slider to 0 to disable the axes display.

Source

[Mihai]

Cool, so it would be the same as in Studio. You just have to pull the geometry up and away from you.

[Polyxo]

Cool, so it would be the same as in Studio. You just have to pull the geometry up and away from you.

Sorry, no C4D here.

[Mihai]

Could you please try sculpting this shape in Zbrush, and export as tangent space, and use the first 1-5 flipand switch?

[Polyxo]

I just did this from a default plane in the orientation you suggested.
The result is pitch-black in all instances and even by upping the exposure nothing only remotely usable appears.

Then I redid the UV's on the plane so that they do no longer the Zbrush internal Ptex-derivate was used
but just a single square UV-Island. These maps start looking "somewhat" better.

You can find these here, as ordered with flip and switch 1-5 (of 48 total options).

But it should be noted that there's also the option to flip and switch tangents (48 total options)as well as Tangent Eval-Mode (3 options).
See attachment 2 for these sliders. What about these settings? Thus far I left them untouched.

[Mihai]

Thanks but all the files look exactly the same in the R,G,B channels?..........
What's the Tangent eval mode?

I think perhaps you need to also change the TangentFlipandSwitch, so it's the same as the Flipandswitch. Then maybe the files will be different.

[Polyxo]

Thanks but all the files look exactly the same in the R,G,B channels?..........

Yes. I see this now too - I just saved them out quickly without looking closely.

What's the Tangent eval mode?

No idea. It's not even mentioned in the documentation. The Tooltips only says that the default value is 1
What is ok, given that Pixologic actually wanted to avoid that their users have to fumble around in this area...

I think perhaps you need to also change the TangentFlipandSwitch, so it's the same as the Flipandswitch. Then maybe the files will be different.

Ok, here are just to get a first impression the first 5 with numbers in sync (1-1, 2-2 etc.)

But I figure that I needed until the end of the week to save out all possible options...
There must be a somewhat smarter way...
Can't the big brains at NL and Pix have a quick chat on that matter?