# Questions tagged [raytracing]

Questions specific to raytracing (as opposed to scanline rendering), the 3D graphics technique of intersecting rays from the camera with objects in the scene.

113 questions with no upvoted or accepted answers
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• 193
581 views

### Implementing GGX VNDF importance sampling with DXR

I am currently implementing the GGX specular BRDF in a DXR raytracer using the importance sampling method describe by Heitz I am sampling the VNDF with: ...
• 21
420 views

### The termination probability of Russian roulette in PBRT

As described in PBRT 14.5, the path tracer stops bouncing rays at a probability q, which is determined by the throughput of the path. ...
• 119
597 views

### What's the nature of Monte Carlo noise?

Monte Carlo rendering is just a process of sampling and reconstruction to evaluate the rendering equation. Why is it called noise rather than error?
• 591
160 views

### Picking multiple light sources from a mixture densities

According to Peter Shirely paper, one pdf(probability density function) can be defined for the union of the light sources and pick only one using a random number from this density: p(x) = \alpha_1 ...
• 730
583 views

### Calculating intensities of Virtual Point Lights in Instant Radiosity from IES lights

Short introduction I created a function that interpolates the IES luminious intensities (candelas) using Hermite interpolation, so in my code all light sources have $I(\theta, \phi)$ function - but ...
1 vote
24 views

### What is the difference between Uniform/Storage Buffer and Hitgroup Record data buffer?

I have a vulkan ray tracer in which I uploaded my vertices as a single buffer (for all meshes in the scene) as a storage buffer. I have one closest hit shader per way-of-calculating-lighting (e.g. one ...
• 1,541
1 vote
32 views

### Why would an image look the same pre-raytracing and post-raytracing?

I am trying to raytrace an image of a black hole, but given my current difficulties of doing so with the formalism of relativity, I've decided to do my raytracing using Newton's law of gravitation ...
• 111
1 vote
137 views

### Importance sampling of the blinn-phong brdf in pathtracing

tl;dr: How do you importance sample the blinn-phong-brdf? Recipe for importance sampling of the phong brdf as far as i understood it (pseudo-code): ...
1 vote
55 views

### What is this cardioid/fish-like graphic that appears in FFXVI when looking at the sun?

In Final Fantasy 16, a recent video game, when looking towards the setting sun, one sees several circles, which seem like the lens flare that one commonly sees in games. But the most prominent (circle)...
• 111
1 vote
63 views

• 11
1 vote
449 views

### Raytracing and transformation

So I'm looking at incorporating instancing to my ray tracer. However what I would like some insight on is what to apply the transformation to?. Most suggest to apply the inverse transformation to the ...
1 vote
91 views

### Why my bsdf can not pass Chi2test?

I implemented a MicrofacetTransmission in nori. But it can not pass all Chi2test when alpha is large(>= 0.4 or ?),part of chi2test is passed.And I can not found the problem.Can someone help me? ...
• 31
1 vote
130 views

### Time Interval Ray Tracing performance

I found a very nice paper regarding Time Interval Ray Tracing for Motion Blur published in 2017. That was before RTX GPUs were on the market. I have a few questions about an optimal implementation and ...
• 1,136
1 vote
112 views

### Shadow Bug when Raytracing Triangles

Spheres with shadows work fine. But when I try to include triangles with shadows, they are shaded incorrectly (i.e completely black): But when I disable shadows Blinn shading on triangles work fine (...
• 131
1 vote
321 views

### Combining two images based on their depth maps

Lets assume, we have two depth maps with us and their corresponding color maps. Now, our task is to populate a final image that will be displayed. Each pixel in the final image needs to be calculated ...
• 111
1 vote