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<DIV><FONT face=Arial size=2>Hello,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have some questions regarding the plasdata
material. I couldn' t find a documentation about it, thats why i must ask
you.</FONT><FONT face=Arial size=2></FONT></DIV>
<DIV><FONT face=Arial size=2>The material definition is:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>void plasdata blue</FONT></DIV>
<DIV><FONT face=Arial size=2>6 noop daten2.dat blue.cal sigma phi theta
<BR>0<BR>4 0.1973 0.35612 0.6353 1</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>
<DIV><FONT face=Arial size=2>The unit of the values is (1/sr), I think
no further computation is needed in this case, thats why I took the
"noop"-Argument. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT><FONT face=Arial
size=2></FONT> </DIV></DIV>
<DIV><FONT face=Arial size=2>the cal-file contains only the three
angles:</FONT></DIV>
<DIV><FONT face=Arial size=2>sigma(x,y,z) =
acos(x*Nx+y*Ny+z*Nz)*180/PI;</FONT></DIV>
<DIV>
<P><FONT face=Arial size=2>phi(x,y,z) = acos( -(x*Dx+y*Dy+ z*Dz));</FONT></P>
<P><FONT face=Arial size=2>theta(x,y,z) =
acos(Dx*Nx+Dy*Ny+Dz*Nz)*180/PI;</FONT></P>
<P><FONT face=Arial size=2>sigma should define the angle between incoming light
and surface normal, theta is the one between leaving light and normal and phi is
the one between theta and sigma ... and I'm not sure, wheter the above
calculation is right.</FONT></P>
<P><FONT size=2><FONT face=Arial>The next thing is, that I'm a little confused
about</FONT> <FONT face=Arial> the meaning of the last argument in the last
line of the plasdata material. The materials describtion says, that it is a
parameter for defining specularity (?). But when I have a huge amount of
reflectance data, why do i need another parameter? In which way does it
influence the computation of my reflectance values? In the current material
definition it is set to one because, setting it to zero I have a plastic
material as it seems. How can I obtain the right value?</FONT></FONT></P>
<P><FONT size=2><FONT face=Arial>Please take the noob out of the
dark</FONT><FONT face=Arial> :)</FONT></FONT></P>
<P><FONT face=Arial size=2>Cheers,</FONT></P>
<P><FONT face=Arial size=2>Uta</FONT></P></DIV></BODY></HTML>