Photon mapping ownz!

Hi there, it's been a while.

I've implemented progressive photon mapping, first exactly as it is in original paper (constructing hitmap once and shooting photons in the main loop), it was all nice and fast but quite troublesome, especially if it comes to antialiasing and glossy materials.
Then i've implemented the more basic approach to PPM as in this paper.

But I have some isues as for now:

• I am not sure about the adjoint bsdf for shading normals. What's obvious is smooth normals didnt work out of the box for the lambertian. What I did is using original normal, and scaling contribution by |in*nor_s| / |in*nor_g|, kinda works but I am not sure. What with other materials? For specular and dielectric it seems to work with just smoothed normal in place of the geometric one.
• Since I'm still using Java I have problems with Garbage Collector, I build uniform grid for 100000 - 200000 photons every pass on all 8 threads separately and that really kills the GC, even if I try to reuse the grid. Any suggestions?
• Shading on hard corners, for example 90 degree corners between the walls. Right now I use simple hack to check for the angle between the photon and surface normal, but that makes them black, the blackness does shrink over time but doesn't seem to ever disappear. So I wonder if it wouldn't be a better choice to leave it alone converging to the right sollution in +inf time and 1/inf radius (?)

Other than that it's blazing fast. This image took around one hour to render:

But was already pretty good after minutes.

Water caustics

One of the hardcore scenes to test. Forgive me the noise but my bvh is so slow :(.

Cheers.

A little update

Hi there,

What's new:

• Added Beer's law to the glass material - you can tell how absorption varies with the distance traveled (for ex. monkey's ear is barely colored versus it's middle).
• Pixel filtering - added variety of filters. The black border around the light source is due the negative values of mitchell filter.
• Reimplemented simple bvh and .obj parser.

Btw. could somebody tell me:

when I specify my light intensity with pure rgb triplet as its emittance, for ex. (15, 15, 15) - what units are those? And how could I convert between other, perhaps more physically convenient, units? so I could compare my results with other renderers.

Cheers.

Cornell box

I just like them.

I'm back

Yet again starting from scratch. Playing with metropolis.



Naive path tracing on the left, same thing but with metropolis on the right.

Multithreading and some GUI

Hi there,

I've added some multithreading and was playing with gui in swing.

As far as everything was a very pleasant experience, I'm concerned that
I got only ~190% load on my two cores, what means that the speedup is not exactly 2x.

So I've tested sunflowand noticed
that it also doesn't get anywhere near 200% - 180%-190% most likely. So I don't know...

Java path tracing

Hello I'm back.

My current weapon of choice is Java though.

The renderer supports:

• median split BVH,
• thin lens and pinhole camera models,
• sphere and Triangle primitives,
• naive path tracing with lambertian surfaces only,
• rendering in a progressive manner.

Performance is not that bad. I designed it to take full advantage of the new feature of java called Escape Analysis, so I'm not reusing objects (what leads to ugly code btw.) but creating them like crazy.

What sucks though is that there is no 1.6.0_14 java for Mac OS X yet, but I've tested in on windows and it works very well.

Some first, naive path tracing, renderings: