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Smart IBL >> sIBL Developers Corner >> Environment Map Formats
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Message started by Andy on 01/12/07 at 23:59:56

Title: Environment Map Formats
Post by Andy on 01/12/07 at 23:59:56
In XSI, we have 5 formats to choose from for environment maps:

spherical
cylindrical
cubic strip (6 cubic faces arranged in a 6x1 configuration)
cubic cross (6 cubic faces arranged in a "t" shape)
cubic cross sideways (6 cubic faces arranged in a "t" turned on its side, long end pointing right)

And of course, there's the probe format, though it's not supported directly.

I've also noticed that a lot of games use a cubic "+" configuration with the upper left corner filled with the 6th cube, like:

xxo
xxx
oxo

which is efficient for scenarios when you need square textures (games).

What's the story with the currently supported formats?  The four I see are spherical, cylindrical, angular and screen.  Spherical and cylindrical are obvious.  I'm assuming "angular" is refering to the probe maps that look like a big round ball, right?  And from the spec, "screen" is a rectangular background card.

Personally, I'm a pretty big fan of the cubic cross maps for 3 reasons:

1) You can generate them from 3D scenes really easily using and array of 6 standard pinhole cameras.
2) Warping/pinching is minimized
3) They are widely available.

So, if I were to try to add support for these formats to the XSI version of the plugin, what do you guys think would be the best way to go about it?  Can we maybe just add some map types to the spec?

-Andy

Title: Re: Environment Map Formats
Post by Blochi on 01/15/07 at 04:54:35
Great Idea!

I am all for it. It would be easy for me to implement them as background, for the ENV I am restricted to spherical and angular, and reflection maps are purely spherical in LW.

Still, there should be descriptions possible in the format.

Blochi

Title: Re: Environment Map Formats
Post by tischbein3 on 01/15/07 at 05:02:02
Nice idea, to support cubic maps,
although the implementation of the projection transformation is a bit tricky, (but solveable)

The only thing is: I'm not a favorite towards the cubic cross format, because they are invitation for memory waste (if implmented the wrong.)

But in general nice idea. :)

chris

Title: Re: Environment Map Formats
Post by Blochi on 01/15/07 at 16:41:09
OK, I have just found a plugin that would enable cubic ENV maps in LW.

Lets all get on the same page about the index numbers:

1 ... Spherical
2 ... Cylindrical
3 ... Angular map
4 ... rectangular BG projection
5 ... Cubic Strip
6 ... Cubic, Horizontal Cross
7 ... Cubic, Vertical Cross

For a 100% compatible SDR set the preferred choice would be 1:Spherical, simply because this is (and can be) implemented already in all our importers. Over time, as we find ways to get the others supported, this might ramp up...

How does that sound?

Blochi

Title: Re: Environment Map Formats
Post by tischbein3 on 01/20/07 at 20:01:09
Well I do have  question: / wish :)

Could both of you describe the order of the faces ?
After some more tests, it seems this is not allways the same / depending on soft used.

thanks
chris

Title: Re: Environment Map Formats
Post by tischbein3 on 01/22/07 at 00:16:50
andy, are these mapping order / orientations for cubic stripe really correct ?

http://www.edharriss.com/tutorials/tutorial_xsi_cubic_envmap/xsi_cubic_env_map_files/cubic_template_xsi.jpg

as described here:

http://www.edharriss.com/tutorials/tutorial_xsi_cubic_envmap/xsi_cubic_env_map.htm

seems to me quite illogical.....

Title: Re: Environment Map Formats
Post by Dschaga on 01/23/07 at 22:59:08
Please don't forget, that we want to design a crossplatform tool!

If we start supporting a projectiontype, which isn't supported on all available 3d apps, we maybe loose some agruments why the SDR is so great.

Title: Re: Environment Map Formats
Post by tischbein3 on 01/25/07 at 10:55:26
Does max support it ? if yes, does it have the same orientation of the faces ?




Title: Re: Environment Map Formats
Post by Dschaga on 01/29/07 at 12:19:33
as far as i know , max doesn't support cubic mapping.

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