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.

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11 views

Can someone explain why raytracing isn't able to make Global Illumination?

I've watched a few videos about raytracing vs pathtracing, and one thing that consistently pops up is the idea that pathtracing seems to be able to do global illumination, whilst raytracing is not. ...
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3answers
603 views

Fundamental drawbacks of rasterization over ray tracing

Are there any fundamental drawbacks/limitations of rasterization as compared to ray-tracing? When I search on the internet, I get vague explanations like rasterization does not provide lighting ...
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30 views

Raytracing, divide by PDF neutralized the effect of D and G terms, what is the problem?

Following some documents on internet, I divide my ray tracing result by PDF. Then it seem the D and G terms disappeared. Only F term is still visible, it looks like Fresnel only. ...
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1answer
56 views

Ray tracing Bug with Diffuse material

I am trying to do ray tracing in python (following the tutorial given in Ray Tracing in a weekend). Basically I am shooting rays from eye and the recursively bounce around, each time they hit ...
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1answer
73 views

Ray tracing geometries with same position, translation and scale

this is my first post on the Computer Graphics Stackexchange forum. Apologies in advance if I am doing something wrong. I have the problem that I have a scene with overlapping geometries. To be more ...
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109 views

Ray casting and rasterization 101

Recently I've became an intern in company-name and my internship task is(for now) create rasterization using rays. I'm mostly interested in pure math, so basic ...
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0answers
78 views

Path tracing : fireflies/hot pixels when directly sampling lights

I am implementing a pathtracer with both indirect and direct light sampling at each intersection (I believe the "direct light sampling" part is also referred to as "next event ...
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1answer
46 views

What can be the cause of some strange ray shadows artefacts on a perfectly flat surface?

First of all I have to say that I am really new in the world of Computer Graphics. I apologise if some of my questions may appear trivial. I am currently using a non-commercial ray tracing and ...
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0answers
41 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 ...
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0answers
29 views

Unity path tracing makes the pc crash

Good Morning. I'm testing Path Tracing techniques with unity, following this tutorial. http://three-eyed-games.com/2019/03/18/gpu-path-tracing-in-unity-part-3/ But I'm in trouble. Whenever I try to ...
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1answer
105 views

Given two 3d vectors, find the rotation matrix between the two

So I am making a raytracer following the very helpful online book of Gabriel Gambetta but I stumble on the rotation matrix part. My linear algebra background is 3Blue1Brown video series "The ...
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1answer
73 views

Magic number meaning in smallpt's camera ray calculation

In smallpt's source at line 90 the direction is multiplied by 140 and I was wondering where that number is coming from. I was hoping for it to be explained in the ...
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1answer
48 views

Buggy behavior when applying specular reflection

I'm very new to computer graphics and trying to implement a raytracer based on the book Computer Graphics from Scratch. When I tried to add specular reflection, I don't get the output that look like ...
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1answer
51 views

(Ray tracing) Trouble converting to screen coordinates, objects being stretched

I followed along with Ray Tracing in One Weekend and managed to get the final output but I wanted to understand more about creating a camera and "painting" the screen since he didn't go over ...
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0answers
32 views

Calculate Ray-Box intersections in terms of distance

Given a ray and a cube, how do I calculate the two intersections between them in terms of distance along the ray. Would be good if the results would be NaN or Infinity if they do not intersect. So far ...
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0answers
40 views

Path tracing: how to ensure the new direction vector is a valid direction vector with respect to a BSDF?

Given the BSDF function and the Normal vector of the intersection point in world space, how can I generate a new direction vector ...
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1answer
47 views

How to link Intel Open Image Denoise in Qt Creator and use it to denoise noisy Monte Carlo path tracing renderings?

I've been trying to link my the Intel Open Image Denoise libraries for about a week and still have no luck as of now. This could partly be because I am also novice in C++ stuff. So I need some help in ...
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1answer
134 views

Transforming a ray from camera space to world space

I am writing a Raytracer and generating rays from the camera. I have a working program but slightly confused about the linear algebra concepts involved in transforming the ray from camera space to ...
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1answer
24 views

Moving a vertex through the cursor

There is a way to move a selected point in a mesh with a cursor(assuming a camera that doesn;t change between frames). The way I remember the algorithm (but seems to be wrong) is: Unproject the ...
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1answer
72 views

Does film filter introduce bias in path tracing?

Does using box or gaussian filter introduce bias to the image when reconstructing the pixel? Bias does not seem to be talked in the Chapter 7.8 of PBRT
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2answers
144 views

Mathematical Foundations of Radiative Transfer

I'm new to learning about ray tracing, but have been fairly confused by the mathematical foundations of it all. Specifically of radiometry/radiative transfer. I've internet searched a lot and skimmed ...
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0answers
40 views

How many years till photorealistic games? [closed]

I just saw this post by NVIDIA: RTX Global Illumination The images shown seem to be rendered in realtime which got me thinking about when games will achieve full photorealism and become ...
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0answers
36 views

Halton raytracer light path

I"m currently making my own graphic engine. I have the bsdf acquisition and various textures acquisition and I have materials suited for special type of light paths. did"t code the rendering ...
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0answers
35 views

Create a virtual server which use the full power of my GPU

i dont know if i can create a virtual server (with vmware, virtual box or with something like that), and if i can use the full power of my graph (i have a nvidia rtx 2080 super) or if I'm going to ...
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0answers
31 views

GL_OUT_OF_MEMORY Error when glDispatchCompute takes longer

I built a simple Ray Tracer which takes use of OpenGL's Compute Shader and traces ".obj" Files. The results are passed to the Host-Program via glMapBufferRange after finishing computing. ...
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1answer
100 views

Ray tracing where illumination itself affects the geometry

I am interested in a scientific application in which ray tracing is necessary, but also where the light itself alters the geometry of the surface mesh (imagine perhaps that the beams of light have ...
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1answer
129 views

Why is the image from the CUDA version not as sharp as the CPU version?

I am extending Roger Allen's Ray Tracing in One Weekend in CUDA (and also here) by following Peter Shirley's Ray Tracing: The Next Week; specifically Image Texture Mapping. The image I obtain from ...
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2answers
108 views

BVH uses aabb for a sphere in Ray Tracing: The Next Week

While studying Peter Shirley's Ray Tracing:The Next Week, I came across an issue that I cannot quite figure out: Stepping through the random_scene() case of the ...
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1answer
76 views

Debugging refraction in a sphere

I have been working on recreating some of the scenes from Peter Shirley's raytracing books using compute shaders and the new Metal raytracing API. It is going well but I am having some trouble with ...
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1answer
126 views

How do we know if a ray intersected a triangle in one in a million

I've taken a class about ray-plane intersection on this: https://www.khanacademy.org/computing/pixar/rendering/rendering-2/v/rendering-5 Suppose we shoot a ray at the scene and this scene contains ...
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1answer
79 views

Pathtracing - many bounces reduce shadows

I'm creating DXR PathTracer highly influence by Matt Pettineo's one - https://github.com/TheRealMJP/DXRPathTracer ; Relevant HLSL code below: ...
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1answer
105 views

Importance sampling GGX NDF - fireflies and bright final result

https://schuttejoe.github.io/post/ggximportancesamplingpart1/ - I have problem implementing this method. Somebody asked question about this before ( Can't understand the Importance sampling GGX ) ...
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1answer
89 views

Deriving radiance from irradiance and intensity

I'm reading PBRT and am stuck in chapter 5.4 about radiometry. In particular: We define the irradiance as the average density flux arriving at a surface with units $\frac{W}{m^2}$. So for a point ...
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1answer
102 views

Importance sampling a cosine distribution

Let's take a look at this blog article - https://schuttejoe.github.io/post/ggximportancesamplingpart1/ and image presented as a result of implementing it: Inside above link, you can see description ...
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1answer
175 views

Why does my image has a square pattern in cuda path tracer?

I am writting a path tracer in cuda following the Shirley's book. I am having a square pattern as an output. The size of the block change if I change the block dimensions. For this image, the block ...
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1answer
116 views

Path tracing - cannot converge diffuse sampling + oversaturation

I'm in process of creating progressive path tracer using DX12 + DXR. I managed to create working raytracing code + pathtracing code with multiple bounces but I'm experiencing problems stated below (...
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1answer
56 views

Worsening sampling quality of raytracing with increasing distance from world origin

I am using RT shader (DXR) to generate g-buffers with code below. There was no problems with smaller scene (pink room from cwyman tutorial - http://cwyman.org/code/dxrTutors/tutors/Tutor5/tutorial05....
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1answer
78 views

What should I do when a new sampled direction is below a normal oriented hemisphere?

I generate random directions from the pdf of D term in GGX BRDF. On the picture, white dots are new directions and the cross is the light direction, with roughness = 1. What should I do with the ...
2
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0answers
52 views

Global root signature crash

I have a problem with RTPSO creation. Using local root signatures for each of rgs (ray generation shader), chs (closest hit), miss is working correctly. However, for performance sake, I want to use ...
2
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0answers
109 views

BVH works fine, but why does it slow down a lot when using Cornell Box? How to improve it?

I am using the SAH-BVH from PBRT-v3, it works fine for triangle-mesh, especially for dense mesh. But here is a problem. If I added Cornell box while building the BVH tree, the BVH performance will ...
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2answers
153 views

Ray Tracing, why does the GGX make my rendering result darker and darker for each frame?

I am trying to add GGX and PBR textures to my GPU ray tracer. The result is very strange, it's getting darker for each frame. ...
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1answer
95 views

Raytracer help - Background color writing over some colors?

I'm implementing Peter Shirley's "Raytracer in a Weekend: The next week" and I'm having some trouble with rendering a scene with a light. I'm not sure if the issue is the background color or ...
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1answer
55 views

Hit group - export already defined

I am getting this error when creating RTPSO with multiple hit groups: ...
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0answers
65 views

Euclideon Unlimited Details Voxel Engine Architecture

As I understand Euclideon haven't just rendered voxels for these infamous demos, since the amount of geometry is still too large for the 2010 PC with software raytracer and the model taking whole HDD ...
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0answers
80 views

How does one obtain SDF of an octree?

As I understand the usual practice is to obtain the SDF by the means of a KD-tree. But the KD-tree generation and the lookup (for each ray step) are, well, slow, while the octree can be easily ...
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1answer
47 views

Texture value clamped to 1

I am working on ray/path-tracer using DXR and I'm starting with simple AO. In first pass, I am storing normal value and RayTCurrent(): ...
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2answers
1k views

Is BVH faster than the octree/kd-tree for raytracing the objects on a GPU?

Apparently most people use BVHs in their raytracers. The ray-AABB intersection code is very fast and and the BVHs also compresses empty space efficiently, working even with infinitely large objects, ...
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2answers
293 views

Why is eye-based ray tracing preferred over light-based ray tracing?

It seems that virtually all path tracers use eye-based or view-based path tracing. That is, the light rays originate from the camera rather than the light source. The reason given for this everywhere ...
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0answers
52 views

What's a good research topic in Computer Graphics?

I am currently trying to find topics for my master's thesis. I would really like to do something in the field of computer graphics, but I've been having trouble finding what are some current problems ...
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1answer
83 views

Rendering moist/wet materials like human anatomies for surgical simulators

Real human anatomies look wet/ moist when operated. I am looking for some good methods for rendering anatomies in a virtual simulation, and hence I have done a literature survey on 'Rendering wet ...

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