My little path tracer

A picture is worth a thousand words.
dawelter
Posts: 6
Joined: Sun Oct 29, 2017 3:15 pm

My little path tracer

Postby dawelter » Sat Dec 09, 2017 8:39 am

This came out of my path tracer.
cornelbox3.jpg
cornelbox3.jpg (161.07 KiB) Viewed 277 times


Unfortunately convergence stagnated after some 10k samples per pixel. Not unexpected since it is a difficult scene. Lit by two point lights through the holes in the ceiling. I haven't implemented area lights. The medium has chromatic collision coefficients with high scattering for blue wavelengths.

Cheers

dawelter
Posts: 6
Joined: Sun Oct 29, 2017 3:15 pm

Re: My little path tracer

Postby dawelter » Mon Dec 11, 2017 12:42 pm

Trying to reproduce results from Peter Kutz's Sky Render.
Using 10 discrete wavelengths, no ozone, purely exponential density decrease. Something is wrong. Much too greenish for my taste.
atmosphere_fisheye1.jpg
atmosphere_fisheye1.jpg (61.03 KiB) Viewed 234 times

atmosphere_fisheye2.jpg
atmosphere_fisheye2.jpg (46.42 KiB) Viewed 234 times

My approximation to the solar emission spectrum might be inadequate in the blue wavelengths :roll:
solarspectrum10bins.png
solarspectrum10bins.png (14.11 KiB) Viewed 234 times


EDIT:
Yeah that looks better!
https://www.dropbox.com/s/0jjsmpi5jvfmi ... 3.jpg?dl=0
https://www.dropbox.com/s/nh80qd93qnbje ... 4.jpg?dl=0

I changed two things at once: 36 bins instead of 10. sRGB output instead of CIE RGB 1931 because if I tell CIMG to write jpg it is probably going to be interpreted as sRGB.

Because I need RGB to spectrum conversions, I implemented the way of Smits (1999) but with more bins (kind of). The code is easily adaptable. I put it up on github: https://github.com/DaWelter/ToyTrace/bl ... sWay.ipynb


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