Cut Crystal Tests

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WytRaven
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Post by WytRaven » Sat Oct 13, 2007 9:34 pm

Because Ono wanted to see them as a straight line hence the 1/λ².
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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WytRaven
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Post by WytRaven » Sat Oct 13, 2007 10:59 pm

Ono, as discussed:

Image
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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Post by WytRaven » Sun Oct 14, 2007 12:41 am

Ono, 3 way comparison of SF10 glass.

Original:
Image

2nd method:
Image

2nd method using principal dispersion wavelengths:
Image


2nd way has the centre spectrum issues I mentioned. This does seem to be drawing a line 'through' the measured data.

3rd way fits the curve best for the majority of the visible spectrum. Fits better than original method but still drops of through violet.
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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Kram1032
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Post by Kram1032 » Sun Oct 14, 2007 1:04 am

what's the actual difference in the three methods?
I'd say, a mix of 2nd and 3rd would give the best match, if there is any way to do that...
'cause 2nd is *quite* correct in the violet spectrum, but then, it starts being more incorrect than the 3rd.
1st is least accurate...

Can you think of any way, to mix 2nd and 3rd mode? For example, you could (maybe) blend them from 2nd to 3rd :)
(a quite quick blend, should already be in the middle of the two, at 442.5 nm or something :))

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WytRaven
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Post by WytRaven » Sun Oct 14, 2007 1:16 am

Here are the details:

The first method uses the gradient of a line drawn between nF and nC (the principal dispersion), using um^2 for the wavelength measurements (x), to get B and a rearranged cauchy equation to solve for A

The second method uses the gradient of a straight line between 400nm and 700nm, using um^-2 for the wavelength measurements, to get B and using B finds the y intercept (x = 0) to get A.

The third method uses the same equations as the second method but uses the principal dispersion wavelengths (nF and nC) instead of 400nm and 700nm.
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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WytRaven
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Post by WytRaven » Sun Oct 14, 2007 1:19 am

Ono seems to ahve fallen asleep in IRC ;) so I have yet to get his opinion on this. I personally think that this is why Sellmeier revised Cauchy; Cauchy simply isn't accurate enough across the spectrum for all mediums whereas Sellmeier is.
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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WytRaven
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Post by WytRaven » Sun Oct 14, 2007 2:02 am

Well at 200h 20m I pulled the plug. Afterall this test is already known to be massively incorrect. I will post result in Finished Renders.
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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Kram1032
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Post by Kram1032 » Sun Oct 14, 2007 7:29 am

:shock: a 12020 min render, and you don't show it? :(
8 days 8 hours and 20 minutes!!!! You're crazy, man O.o

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WytRaven
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Post by WytRaven » Sun Oct 14, 2007 7:35 am

Um Kram...it's in finished renders :P
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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Kram1032
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Post by Kram1032 » Sun Oct 14, 2007 7:54 am

Oh xD
I misread it - I thought, you'll post the absolute final result with updated mat, or something xD^^

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WytRaven
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Post by WytRaven » Wed Oct 17, 2007 1:31 am

Version 14 of Schott Glass Catalog spreadsheet available

EDIT: Link removed - See thread entitled Tabulated Schott Glass Catalog.

@Ono: A and B calcs used in this are those based on um^-2 please take a look and see what I mean about the odd results. These calcs seem to result in either a near perfect fit or a really bad fit from glass to glass.
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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CoolColJ
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Post by CoolColJ » Fri Oct 26, 2007 8:20 pm

WytRaven wrote:
CoolColJ wrote:not the archive itself, I can unpack it with Winrar just fine, but read the file itself :)
It's jsut a standard Office 97-2003 Excel spreadsheet. If you aren't on windows and/or don't have MS Office then I guess something like Open Office would be a good start?
this does it if you don't have the programs - Like me

http://www.microsoft.com/downloads/deta ... laylang=EN

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CoolColJ
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Post by CoolColJ » Fri Oct 26, 2007 8:43 pm

I realise now all the maths I learnt at school come is actually useful....

along with a scientific calculator :)
http://www.calculator.com/calcs/calc_sci.html

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WytRaven
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Post by WytRaven » Fri Oct 26, 2007 8:46 pm

not sure but i would doubt that that excel view would support addons in which case the spline function used to interpolate transmitance values wont work and the resulting data will be skewed all over the place.
:idea: "A foolish consistency is the hobgoblin of little minds..." - Emerson 1841

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CoolColJ
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Post by CoolColJ » Fri Oct 26, 2007 8:53 pm

better than nothing though :)
I can use it to view the data of the gems I posted in that mineral data topic anyway

did you have Excel do all the calculations for you?

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