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Sibl flipped (Read 2980 times)
pjano
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Sibl flipped
01/24/12 at 08:03:13
 
Hello,
I am a new user so maybe there is a simple solution to my problem.Here is what I do:
1. load an unwrapped Hdr from a sphere to SiblEdit and let it make the set.
2. Apply Vray preset for 3ds Max in Sibl Gui 4
3 export to 3ds Max2012
4. everything is fine except that all maps are horizontally flipped. The reflection map, the background.

I could easily fix that by applying the flip in PS before importing to Sibl but I guess that there is something wrong I am doing in the first place.
Can anyone point me in the right direction?
Many thanks in advance
Piotr
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Kel Solaar
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Re: Sibl flipped
Reply #1 - 01/24/12 at 10:08:46
 
Hello,

Mmmh is it in the viewport or at render time? I just checked for sake of checking but I can't reproduce that issue.

KS
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pjano
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Re: Sibl flipped
Reply #2 - 01/24/12 at 10:42:17
 
Hello,
Yes. I can see the flipped effect both in the viewport and in the render. I also tried to reproduce it the other way around. I flipped the original HDRi image horizontally,made the Sibl set and put it to the max scene. After that everything looks correctly oriented. It is a simple workaround but what bothers me more is that I don't have any idea why this is happening. The original HDR was shot from the same angle as my background plate.
I unwrapped it the way I would normally do in HDRshop.
Anyone had this issue?
Thank You
Piotr
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Kel Solaar
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Re: Sibl flipped
Reply #3 - 01/24/12 at 12:12:50
 
Hi,

Is it possible to upload some screenshots of your original hdr file, the generated Ibl Set reflection file and a render please? Here is a screengrab I did a bit earlier:

...

KS
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pjano
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Re: Sibl flipped
Reply #4 - 01/25/12 at 19:41:11
 
Hi!

After further testing it seems that I made a stupid mistake while unwrapping. Anyway, the whole concept of Sibl is amazing. Thank You for such a great tool!!! Smiley
Piotr
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Kel Solaar
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Re: Sibl flipped
Reply #5 - 01/25/12 at 19:45:40
 
Hi,

Glad you pinpointed the issue Smiley I was starting to think I may have missed something VERY obvious Smiley

Have fun!

KS
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Blochi
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Re: Sibl flipped
Reply #6 - 01/25/12 at 20:52:10
 
Hi PJano,

I was getting worried as well.

When a sIBL set is loaded, it DOES flip the texture. That is one of the things necessary to make it look correct. The reason is, that without sIBL, just regularly mapping an image on a sphere, that will be the wrong direction. Because spherical mapping is traditionally meant to be seen from the outside, but we are looking at the inside of a sphere. Most tutorials on "HDR lighting by hand" forget about this part. Some dedicated sky shaders get it correct, but it has always been a point of confusion.

That's why we decided early on that sIBL importers will always map the image in a way that looking at the flat panorama, and looking at the center of the skyball from the inside are conform.

Here is a sketch of the standard spherical mapping, that sIBL is compensating for.
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11_mapping_spherical_direction.jpg (Attachment deleted)
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Blochi
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Re: Sibl flipped
Reply #7 - 01/25/12 at 20:54:08
 
PS: And when you shoot your HDR with a mirror ball, yes, then your initial panorama unwrap is in fact mirrored.
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Kel Solaar
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Re: Sibl flipped
Reply #8 - 01/25/12 at 21:54:24
 
Nice text ball :]

KS
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