Search found 23 matches

Search found 23 matches
by tinman999
Wed May 09, 2007 12:25 pm
Forum: Indigo General Stuff
Topic: Converting your RGB colour To NK
Replies: 54
Views: 19296

Converting your RGB colour To NK

Here is a win32 program that convert most of the RGB colour to NK http://www.renderlight.co.uk/images/nktest.png http://www.renderlight.co.uk/images/rgbtonk.png http://www.renderlight.co.uk/files/rgbtonk.exe Just enter the rgb value and press 'To NK' button. The result nk data should be display in t...
by tinman999
Wed May 09, 2007 8:52 am
Forum: Indigo General Stuff
Topic: NK - physically correct? (not this time ;)
Replies: 20
Views: 3851

sth wrote:I found this on google...
http://swiss.csail.mit.edu/~jaffer/FreeSnell/
What do you think about it? :?:
This is just the NK database
by tinman999
Wed May 09, 2007 4:38 am
Forum: Indigo General Stuff
Topic: NK - physically correct? (not this time ;)
Replies: 20
Views: 3851

one way of doing it: Assuming the extinction coefficent is zero refraction index = (1+sqrt(R))/((1-sqrt(R)) where 0 <= R < 1 To give you an example suppose you have rgb colour of value <0.0, 0.9, 0.0> (green) use the above formula red refraction index = (1+sqrt(0))/(1-sqrt(0)) -> 1 green refrcation ...
by tinman999
Wed May 09, 2007 3:21 am
Forum: Indigo General Stuff
Topic: NK - physically correct? (not this time ;)
Replies: 20
Views: 3851

first line tell you what the measurements is, after that the data itself specify in the form of complex refraction index (real part - refraction index, imaginary part - extinction coefficient)
by tinman999
Wed May 09, 2007 3:15 am
Forum: Bugs and Requests
Topic: [BUG] NK data file parsing
Replies: 9
Views: 3383

You really need more than nk file to defined gems nk file give you the refraction index, As far as I can tell for dielectric they only gives you the real part of the refraction index and rarely give the imaginary part which give the extinction coefficent (from that you can get the absorption coeffic...
by tinman999
Fri May 04, 2007 11:54 am
Forum: Exporter Development
Topic: chiu filter
Replies: 18
Views: 6321

I think this is the bloom filter implemented in indigo. Spatially Nonuniform Scaling Functions for High Contrast Images http://www.graphicsinterface.org/pre1996/93-ChiuEtAl.pdf I have not look at the source but I think it implemented the version giving in Physically Based Rendering by M Pharr et al
by tinman999
Thu Apr 26, 2007 9:17 am
Forum: Bugs and Requests
Topic: Indigo image quality.
Replies: 16
Views: 3919

IMO mitchell netravali filter is not good for filtering global illumination image, and indeed any filter which uses negative weights unless you apply the filter after you tonemapped your global illumination image. This is because the negative weights of the mitchell netravali can cause black edges (...
by tinman999
Tue Apr 17, 2007 1:34 pm
Forum: Indigo General Stuff
Topic: Looking for definition of nk file format
Replies: 9
Views: 1534

first line

first value = unit of measurement (for example 1 - electron volt, 2 - micrometre)
second-third value = range of measurement
fourth value = number of interval
Search found 23 matches