## Search found 89 matches

Tue Feb 23, 2016 12:37 am
Forum: General Development
Topic: A better way to sample a sphere (w.r.t. solid angle)
Replies: 16
Views: 22587

### Re: A better way to sample a sphere (w.r.t. solid angle)

The only problem is the calculation of the solid-angle/PdfA (area from the left to the right light-point). Well, yes, but that's a big "only". It's potentially a large fraction of your solid angle.. Where get I problems with the sampling-density / accuracy? In my sample-picture, I use a uniform-dis...
Mon Feb 22, 2016 1:54 pm
Forum: General Development
Topic: A better way to sample a sphere (w.r.t. solid angle)
Replies: 16
Views: 22587

### Re: A better way to sample a sphere (w.r.t. solid angle)

There is a disk with the radius from the sphere and his center is the same as the sphere. The normal from the disc shows to the point, that you want to illuminate (hitpoint). You sample than the disc and shoot a shadow-ray from the hitpoint to the sampled disc-point. It probably gives decent-lookin...
Sat Jan 09, 2016 3:08 pm
Forum: Data Sets
Topic: Bezier surface models
Replies: 4
Views: 14735

### Re: Bezier surface models

such curve-patch-models occupy far less space in memory than fat triangle ones - ...Sometimes. NURBS is fine for things like designing mint-condition man-made objects (where smooth, curved, and shiny is important). If you have a lot of geometric detail (nature scenes, scanned 3D objects, etc.), the...
Thu Jan 07, 2016 1:38 am
Forum: Data Sets
Topic: Bezier surface models
Replies: 4
Views: 14735

### Re: Bezier surface models

Not offhand, but you could probably generate some from polygonal models (e.g., by converting to PN triangles or subdivision surfaces). I suspect there isn't much call for Bezier models, because if NURBS is more flexible for high-order surfaces.
Wed Jan 06, 2016 12:56 am
Forum: General Development
Topic: Basic question: reflections with glass sphere
Replies: 2
Views: 6013

### Re: Basic question: reflections with glass sphere

The light source is much brighter than the surface behind the sphere. Radiance in the real world doesn't max out at RGB 1,1,1.
Thu Sep 03, 2015 1:30 pm
Forum: General Development
Topic: Combining Path Tracing with MLT
Replies: 2
Views: 4791

### Re: Combining Path Tracing with MLT

I'm not sure thresholding would help. MLT already favors bright paths, and allowing mutations to dim paths would reduce the probability of getting stuck in a small region of path space. I think discontinuities would be noticeable as well.
Wed Jul 15, 2015 2:31 am
Forum: General Development
Topic: Question about normal mapping in Ray tracingIt looks like al
Replies: 7
Views: 8577

### Re: Question about normal mapping in Ray tracingIt looks lik

Typically normal maps are derived from bump maps. It's essentially a precomputation step that saves you from having to calculate surface derivatives at render time, which can be overly expensive when you only have a dozen or so milliseconds to display a frame. On the other hand, normal maps aren't v...
Wed Jun 03, 2015 3:39 pm
Forum: General Development
Topic: Any good reason to use VPLs for rendering?
Replies: 1
Views: 3763

### Re: Any good reason to use VPLs for rendering?

Used naively, probably not, but there are advantages to amortizing the cost of light paths over many eye paths. IGI maps well to GPUs--you path-trace light paths, but can use rasterization and shadow maps instead of eye paths and shadow rays. If you have a lot of VPLs, you can prune the set judiciou...
Thu Apr 02, 2015 7:34 pm
Forum: General Development
Topic: cosine lobe sampling PDF
Replies: 11
Views: 15515

### Re: cosine lobe sampling PDF

The issue I find is that my images appear to get brighter when I use importance sampling due to the PDF always being less than one (well less than Pi) and therefore increasing the radiance when used for division. Surely when sampling the PDF the value should occasionally equal more than one so that...
Sun Oct 19, 2014 10:02 pm
Forum: General Development
Topic: Path tracing accumulation artifacts
Replies: 13
Views: 11067

### Re: Path tracing accumulation artifacts

The image is quite dark, at least on the devices I have handy, so I can't comment on the artifacts themselves. How good is your random number generator?