Search found 17 matches

by Igors
Wed Mar 27, 2019 7:47 am
Forum: General Development
Topic: photon mapping + final gather light leaks
Replies: 3
Views: 3688

Re: photon mapping + final gather light leaks

Hi, papaboo, All Sorry for old themes reanimating but I've same prob (but no solutions) >> A second check you can make that postpones final gathering to avoid leaking is to continue tracing eye rays until the length of the last bounce is higher than your photon gathering radius. (kernel bandwidth). ...
by Igors
Thu Jul 19, 2012 7:48 am
Forum: General Development
Topic: Veach thesis - formula question
Replies: 86
Views: 48737

Re: Veach thesis - formula question

L = Le * |Nl.-Wi1| |N1.Wi1| / r*r This is a lighting coming from area 1.0. That can correspond to a small or large solid angle. But I don't understand how to integrate. If we get some rays and connect something - it does not mean yet all incoming directions are covered * Understanding how the geome...
by Igors
Tue Jul 17, 2012 4:52 pm
Forum: General Development
Topic: Veach thesis - formula question
Replies: 86
Views: 48737

Re: Veach thesis - formula question

spectral wrote: So, if someone has an idea to debug this problem ?
I would store paths' segments (maybe colored) in a text file (for 2 or some shaded points). Then load and view stored paths in 3D app
by Igors
Mon Jul 16, 2012 2:05 pm
Forum: General Development
Topic: Veach thesis - formula question
Replies: 86
Views: 48737

Re: Veach thesis - formula question

What are you guys talking about? :? The formula is perfectly correct, as it applies to infinitesimally small (i.e. differential) solid angles. But count of rays is very finite. For example an area light is a simple rectangle that should be sampled with 100 rays only. In this case the simplified for...
by Igors
Mon Jul 16, 2012 7:50 am
Forum: General Development
Topic: Veach thesis - formula question
Replies: 86
Views: 48737

Re: Veach thesis - formula question

For solid angle defined by 4 normalized vectors (p0, p1, p2, p4 incoming from shading point) I've used light_dir = (Func(p1, p0) + Func(p2, p1) + Func(p3, p2) + Func(p0, p3)) / 2; where Func returns cross(vec0, vec1) * acos(vec0, vec1); It's important to have direction (not scalar only), otherwise s...
by Igors
Sun Jul 15, 2012 4:30 pm
Forum: General Development
Topic: Spherical Light Sampling for direct lighting only
Replies: 6
Views: 5423

Re: Spherical Light Sampling for direct lighting only

There is no some "spherical light", it's a general "area light", just with spherical shape you can get sampling more convenient, as a disk turned face to each point. But all calculations remain same as for area Sample_Illum = Light_intensity * solid_angle / PI2 * dot(sample_dir, surface_normal); At ...
by Igors
Sun Jul 15, 2012 10:51 am
Forum: General Development
Topic: Veach thesis - formula question
Replies: 86
Views: 48737

Re: Veach thesis - formula question

The G formula is a simplified solid angle calculation. But it works well only if light "far enough" (comparing to light area). If x-difference is small it does not produce correct results
by Igors
Tue May 15, 2012 7:15 am
Forum: General Development
Topic: Importance Sampling
Replies: 11
Views: 8708

Re: Importance Sampling

So, first do you implement MIS or BDPT ? have you implemented basic MLT ? For sure it will help a lot ! Sorry, but I'm not familiar with terms. In my prj all bounces are calculated with photon maps, so when a ray hits somethig I already have illumination there (no further paths and rays) A couple o...
by Igors
Sat May 05, 2012 8:10 am
Forum: General Development
Topic: Importance Sampling
Replies: 11
Views: 8708

Re: Importance Sampling

For just that case, this might be an interesting method: http://neulander.org/work/sketch2011.pdf Not very clear "how" - but thx anyway Now I've implemented a simple adaptive sampling. If a ray delivers more color/energy, then "ray's cell" is sampled with additional rays and result is averaged. It ...