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Manifestations of Atmospheric Light Scattering (Mie Theory) http://forum.celestialmatters.org/viewtopic.php?f=9&t=116 
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Author:  scalbers [ Sun, 010315, 21:10 GMT ] 
Post subject:  Re: Manifestations of Atmospheric Light Scattering (Mie Theo 
Greetings Fridger and all, I'll try and study up more on how atmospheres are handled in Celestia. Meanwhile, I've been simulating Earth and Mars atmosphere's including cloud data from any vantage point. http://www.unmannedspaceflight.com/inde ... ntry218019 http://laps.noaa.gov/allsky/allsky.cgi That's it for now, Steve 
Author:  t00fri [ Mon, 020315, 8:18 GMT ] 
Post subject:  Re: Manifestations of Atmospheric Light Scattering (Mie Theo 
scalbers wrote: Greetings Fridger and all, I'll try and study up more on how atmospheres are handled in Celestia. Meanwhile, I've been simulating Earth and Mars atmosphere's including cloud data from any vantage point. http://www.unmannedspaceflight.com/inde ... ntry218019 http://laps.noaa.gov/allsky/allsky.cgi That's it for now Steve Welcome back, Steve! This sounds like a very interesting project of yours. I have a longterm interest in it, notably of course in the context of celestia.Sci development. While many features have been improved a lot or added compared to good old Celestia, atmospheres are still the same simplified Mietheory level... But since I have a very longstanding experience with Mie theory as a scientist, I managed at least to find some pretty good combinations of Mie parameter settings so far. It would be great if you could describe a bit more in detail what you did in your simulations. Fridger 
Author:  scalbers [ Sun, 050415, 15:06 GMT ] 
Post subject:  Re: Manifestations of Atmospheric Light Scattering (Mie Theo 
Yes, this really brings science and art together. For the clear atmosphere I'm considering Rayleigh scattering for the gas component, and Mie scattering for aerosols. There are some details in this powerpoint presentation: http://laps.noaa.gov/albers/ppt/allsky_ ... ation.pptx And some more recent visualizations here (near bottom of page): http://laps.noaa.gov/cgi/albers.homepage.cgi On another note, there are various other rendering packages available that show atmospheric scattering. One is "Proland": http://proland.inrialpes.fr/ That's it for now, Steve 
Author:  hepcatjk [ Fri, 260615, 12:50 GMT ] 
Post subject:  Re: Manifestations of Atmospheric Light Scattering (Mie Theo 
I found the writeup on Cornette Shanks vs HG very enlightening, especially the maple program. It helped fully understand how to treat the g parameter. What I was wondering is how to calculate the CFD for it, so it can be importance sampled Your suppose to take the integral of the PDF, but I didn't have access to Maple and it looks nasty For example for HG: The CDF is Mu = (1/2g)(1+g^2  (1g^2 / 1 + 2gPg)^2 ) Which is derived from P(mu) = 1/2 int 1 to mu ( (1g^2) dmu / (1+g^22g mu)^3/2 ) So I assume to solve this for CS one would have to P(mu) = 1/2 int 1 to mu ( 1.5 * (1.0  g2) * (1.0 + mu* mu) /((2.0 + g2) * pow(1.0 + g2  2.0 * g * mu, 1.5)) ) right? 
Author:  t00fri [ Fri, 260615, 17:34 GMT ] 
Post subject:  Re: Manifestations of Atmospheric Light Scattering (Mie Theo 
Hi hepcatjk, first of all: Welcome at CelestialMatters (CM)! next: for the less initiated readers, let me do a little translation listing of the many acronyms in your post :
hepcatjk wrote: I found the writeup on Cornette Shanks vs HG very enlightening, especially the maple program. It helped fully understand how to treat the g parameter. I guess you meant this: http://www.celestialmatters.org/users/t ... s2/out.pdf Quote: What I was wondering is how to calculate the CFD for it, so it can be importance sampled Your suppose to take the integral of the PDF, but I didn't have access to Maple and it looks nasty For example for HG: The CDF is Mu = (1/2g)(1+g^2  (1g^2 / 1 + 2gPg)^2 ) Which is derived from P(mu) = 1/2 int 1 to mu ( (1g^2) dmu / (1+g^22g mu)^3/2 ) So I assume to solve this for CS one would have to P(mu) = 1/2 int 1 to mu ( 1.5 * (1.0  g2) * (1.0 + mu* mu) /((2.0 + g2) * pow(1.0 + g2  2.0 * g * mu, 1.5)) ) right? Give me a little more time. I'll check it with Maple. There are also many resources in the net about how to calculate CDF from PDF in general. E.g. http://math.ucsd.edu/~tlaetsch/pdf/10C_CDFtoPDF.pdf or Google for "relation between pdf and cdf" Roughly: d/dx CDF(x) = PDF(x) Fridger 
Author:  hepcatjk [ Fri, 260615, 22:44 GMT ] 
Post subject:  Re: Manifestations of Atmospheric Light Scattering (Mie Theo 
Thanks for clarifying my post Also Steve.. love the work! would love to chat... we're up to something similar but have some different results 
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