Mapping anisotropy on a spherical object

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Old 05 May 2013   #1
Question Mapping anisotropy on a spherical object

Hi everyone!

I would need help with mapping the anisotropic angle on a half spehere-like object. I am rendering in Mental Ray and generally using the Arc & Design materials.

Basically I want to create a circularly brushed surface and control the position of the middle of the brushing. Attached a screenshot of what I’ve succeeded to produce so far: mapping a flat UWV map on a sphere creates additional “polars” on the semi-sphere on the left. ( http://area.autodesk.com/userdata/f...001-670x670.jpg )

Now Mr. Neil Blevins has a good tutorial how to do this on a planar object (http://www.neilblevins.com/cg_ed......talray_Renderer). Anyone know how to do this on a sphere?!
 
Old 06 June 2013   #2
Exclamation Anyone?

I'm bringing this up. I've got a deadline approaching. Help anyone, bhlease?

Timo
 
Old 09 September 2013   #3
I'm looking for this too... I've found a solution (a couple of them actually), but they won't work for me, so am after something better!


Solution 1:
Use Autogrid and create a new polygonal object, upon the surface of the current object... at Now attach the original object to this new one. (Has to be that order). Now, poly select the un-needed polys and delete them. Your original object's local axis will now take on the 'Autothe point where you want the anisotropy to stem from (The pole). -grid' created one... and the anisotropy will start from that exact point.

Solution 2:
Add an Xform modifier to your object. Go into Gizmo mode, and rotate the x-form modifier until the z-axis is pointing in the direction you want the 'pole' of anisotropy to be. Now deselect the gizmo, and rotate the ACTUAL object, but back to the original location.


Neither of these work for me, as the scene I'm working on is used as an x-ref in MANY scenes, with animation etc. If I mess with pivot points, or xform modifiers, it will ruin any animation I've done for other scenes. Using the method of 'Map Channel' on the Arch & Design materials doesn't do ANYTHING at all. (BUG?)


Has anyone got any amazing ideas that could get me out of a heap of s**t?

So, I've got objects that are from CAD, they all have different local co-ordinate systems etc, but I want to modify the position of the anisotropy pole WITHOUT messing with pivots.

Any help would be MASSIVELY appreciated!

Thanks,
Tim
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Old 09 September 2013   #4
Thumbs up

Thank you Sir!

I think I got solution 1 working with physical lights. Any ideas how to do this with an HDR map?


Regards,
Timo
 
Old 09 September 2013   #5
Please can you explain a bit more?

The solution should work with any lighting in the scene, including an HDR map as the backdrop.
Or am I not understanding your query properly?
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Old 09 September 2013   #6
Hi,

I'm doing product illustrations. Watches.

I don't use a backdrop in my renderings because it's rather disturbing sometimes.

In my current work flow I have a single skylight to light up my whole scene. For that, I set an (photography studio-like) HDR image as a color map. After doing so, I drag the map into the material browser and set it as an spherical environment. Then for each material I use, I need to assign this same map as an environment map.


Now when I tried the Xform solution I got the reflections from physical lights (I created target spotlights for this) stretching nicely, but it didn't do the trick for the reflections that are caused by my skylight-based HDR environment.
 
Old 09 September 2013   #7
 
Old 09 September 2013   #8
That looks like a nasty little bug to me I'm afraid! Shame it's so annoying to send them a bug report... we've got shitloads of bugs that we'd like to submit, but it's just too tiresome and drawn out... especially when our work machines have no internet connection!


I suggest trying to add a large sphere into the scene, add a 'Normal' modifier, and flip the normals, and then map that sphere with the HDR map... then set it to be invisible, but not to reflections... and see if that works?!?

Good luck!
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Old 09 September 2013   #9
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