Re: Pick dominant light from sh coeffs

"David Neubelt" <[email protected]> Thu, 2 Feb 2012 15:54:11 -0800
Newsgroups gmane.games.devel.algorithms
Message-ID <[email protected]>
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Looks like you want to normalize the 3d vector made from the basis
coefficients (-f[1,1], -f[1,-1], f[1,0]). Section 3.3 ZH Error Analysis
paragraph 2.

=20

-=3D Dave

=20

From: Dan Treble [mailto:[email protected]]=20
Sent: Thursday, February 02, 2012 3:22 PM
To: [email protected]
Subject: [Algorithms] Pick dominant light from sh coeffs

=20

I have 9 red, 9 green and 9 blue sh coefficients (packed using the
method in appendix 10 of
http://www.ppsloan.org/publications/StupidSH36.pdf).

=20

I want to pick a single dominant light to use for specular. How would I
go about efficiently extracting the direction and color of that light
from the coefficients?

=20

Looks like I need to calculate the "optimal linear direction" which is
supposedly in this paper
http://research.microsoft.com/en-us/um/people/johnsny/papers/ldprt.pdf,
however I can't see it. Worse still, if it is in there, it is probably
an integral that I will struggle to turn into code!

=20

Thanks

=20

Dan

=20

=20


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style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>Looks like you want to normalize the 3d vector made from the basis =
coefficients (-f[1,1], -f[1,-1], f[1,0]). Section 3.3 ZH Error Analysis =
paragraph 2.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'><o:p>&nbsp;</o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'>-=3D Dave<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497=
D'><o:p>&nbsp;</o:p></span></p><p class=3DMsoNormal><b><span =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span>=
</b><span style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> =
Dan Treble [mailto:[email protected]] <br><b>Sent:</b> Thursday, =
February 02, 2012 3:22 PM<br><b>To:</b> =
[email protected]<br><b>Subject:</b> [Algorithms] =
Pick dominant light from sh coeffs<o:p></o:p></span></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><div><p class=3DMsoNormal>I =
have&nbsp;9 red, 9 green and 9 blue sh coefficients (packed using the =
method in appendix 10 of&nbsp;<a =
href=3D"http://www.ppsloan.org/publications/StupidSH36.pdf">http://www.pp=
sloan.org/publications/StupidSH36.pdf</a>).<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p></div><p class=3DMsoNormal>I want =
to pick a single&nbsp;dominant&nbsp;light to use for specular. How would =
I go about efficiently extracting the direction and color of that light =
from the coefficients?<o:p></o:p></p><div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p></div><div><p =
class=3DMsoNormal>Looks like I need to calculate the &quot;optimal =
linear direction&quot; which is supposedly in this paper&nbsp;<a =
href=3D"http://research.microsoft.com/en-us/um/people/johnsny/papers/ldpr=
t.pdf">http://research.microsoft.com/en-us/um/people/johnsny/papers/ldprt=
.pdf</a>,&nbsp;however I can't see it.&nbsp;Worse still, if it is in =
there, it is probably an integral that I will struggle to turn into =
code!<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p></div><div><p =
class=3DMsoNormal>Thanks<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p></div><div><p =
class=3DMsoNormal>Dan<o:p></o:p></p></div><div><div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p></div><div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p></div></div></div></body></html>
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