Thread: [Algorithms] Intensity gamma correction of spherical harmonics
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From: Anton K. <kr...@sa...> - 2006-02-26 16:23:12
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Our engine uses spherical harmonics to encode incoming lighting information. Is there a way to make dark areas of the SH sphere darker and bright areas brighter without converting harmonics to image space and applying color correction and than coverting it back to harmonics ? |
From: <Pau...@sc...> - 2006-02-27 09:58:30
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gda...@li... wrote on 26/02/2006 16:23:01: > Our engine uses spherical harmonics to encode incoming lighting information. > > Is there a way to make dark areas of the SH sphere darker and bright areas > brighter > without converting harmonics to image space and applying color correction > and than coverting it back to harmonics ? What about just raising each coefficient to a power? A bit arbitrary, but might work ok... Cheers, Paul. ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify pos...@sc... This footnote also confirms that this email message has been checked for all known viruses. ********************************************************************** Sony Computer Entertainment Europe |
From: Tom F. <tom...@ee...> - 2006-02-28 06:02:34
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The fundamental problem is that the first n terms of an SH are the low-pass-filtered version of the full response. That's the _good thing_ about SHs - they're an accurate representation, up to whatever point you want to stop "paying" for them. The downside is - it's a low-pass filter. It's average. My recommendation is you do your brightest N lights the "normal way" and = put all your less exciting lights in the SH. That way you get the best of = both worlds. Artists can add 30 "mood lights" to the scene and they do the = right thing (in the SH), or they can add one really bright spotlight and it = works exactly as they'd expect - because it's done "properly". TomF. > -----Original Message----- > From: gda...@li...=20 > [mailto:gda...@li...] On=20 > Behalf Of Anton Krupkin > Sent: 26 February 2006 08:23 > To: gda...@li... > Subject: [Algorithms] Intensity gamma correction of spherical=20 > harmonics >=20 >=20 > Our engine uses spherical harmonics to encode incoming=20 > lighting information. >=20 > Is there a way to make dark areas of the SH sphere darker and=20 > bright areas > brighter > without converting harmonics to image space and applying=20 > color correction > and than coverting it back to harmonics ? |
From: Andrew W. <awi...@gm...> - 2006-03-08 07:20:23
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A cheap hack is to scale all the coefficients except for coefficient zero (the constant term) by s > 1. It's the equivalent of doing a contrast stretch: you exaggerate differences from the average colour. Andrew On 2/26/06, Anton Krupkin <kr...@sa...> wrote: > Our engine uses spherical harmonics to encode incoming lighting informati= on. > > Is there a way to make dark areas of the SH sphere darker and bright area= s > brighter > without converting harmonics to image space and applying color correction > and than coverting it back to harmonics ? > > > > > ------------------------------------------------------- > This SF.Net email is sponsored by xPML, a groundbreaking scripting langua= ge > that extends applications into web and mobile media. Attend the live webc= ast > and join the prime developer group breaking into this new coding territor= y! > http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D110944&bid=3D241720&dat= =3D121642 > _______________________________________________ > GDAlgorithms-list mailing list > GDA...@li... > https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 > |