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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Why the ray tracing result looks weird?
I followed the book Ray Tracing in One Weekend and implemented a simple ray tracing procedure. There are 100 random samples every pixel for antialiasing, but the render result looks weird: There is a ...
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Unsolved Problems in CQ to this day?
What problems haven't been solved yet when it comes for instance in rendering,deferred rendering, Volumetric lighting, ambient occlusion or in any other interesting area. When i say unsolved problems, ...
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Why is it easier to inverse transform every object in a scene than to transform a camera?
My lecturer for a computer graphics (raytracing) paper has stated that 'It is easier to apply the inverse transform to the world than it is to apply the transform to the camera.' The example given was ...
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smallpt: ray scattering and Importance Sampling
Introduction
For those familiar with smallpt by Kevin Beason:
In path tracing, when rays hit a surface, they are scattered and the theta angle (the angle between the normal to the surface and the ...
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smallpt: when to stop diffuse ray scattering
For those familiar with smallpt, the ray tracer in 99 lines: I am checking the code, and there is something that is not clear to me in the DIFFUSE ray scattering.
After the rays are shot, they keep ...
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How to account for self intersection with large ray tracing scenes?
I'm working on a hybrid real time ray tracing project and trying to tackle the problem of self-intersection with larger scenes due to loss of float accuracy. The logic I'm trying to use is based on ...
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Monte Carlo Importance Sampling
I am following the "Ray Tracing - the Rest of your Life" book by Peter Shirley and I am facing some troubles in the implementation of Monte Carlo importance sampling, and Direct light sampling.
Monte ...
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How to simulate a line laser diode?
I'm interested in simulating the way a laser line deforms when it strikes an object and runs along the surface of it. Which concepts would be involved? Is there any 3D modeling software out there that ...
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What is a list of common, cheap, real time rendering algorithms?
I am well aware of the existence of Blinn-Phong shading, which is a great tool when you are doing, for example, modelling algorithms and wan't to focus on the model. In this case a full BRDF result, ...
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Ray tracing the next week: understanding Instances
My question is not about the code, but it's about the approach used by the author Peter Shirley (and apparently common practice in ray tracers) of handling Instances. To understand the question it's ...
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Ray tracing in One weeked: issue with metal reflection
Problem
I am following the book Ray tracing in one weekend , and I got stuck after the implementation of the material Metal. I checked my code many times, and it looks exactly like the code ...
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How to set equivalent PDFs for cosine-weighted and uniform-sampled hemispheres?
I'm trying to add BRDFs to a very basic path tracer. Starting out, I'd like to convert just the Lambertian material, with two different sampling methods, to ensure that everything is working right. ...
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Bump mapping with triangles and height maps
I'm trying to add bump mapping to my ray tracer, and I'm currently struggling to add bump mapping to it, as I don't seem to get the transformations from texture space to world space correctly.
I have ...
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How to calculate ray
In ray-tracing technique critical point is to calculate rays which came out from eye $E$ to target $T$ through pixel $P_{ij}$ on viewport. The "viewport" is represented as rectangle divided to square ...
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Get intersection Ray with square
I have a class Ray and Square
public class Rayo {
public Point origen;
public Vector direction;
Square{
X,Y,Widht, height;
}
I need intersection between this ...
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Rendering Equation for photons carrying flux
I am trying to understand the mathematical/physical foundations of photon mapping better.
In the forward photon tracing step it is established, that the rays are carrying portions of total power (...
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How do I convert a hit on an infinite plane to UV coordinates for texturing in a Raytracer?
I am trying to convert a ray hit on an infinite plane, defined by an origin and a normal vector, into UV coordinates, so I can find the appropriate texel at that point.
Code I have is close to ...
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"Artist Friendly Metallic Fresnel" reversible?
While implementing the "Artist Friendly Metallic Fresnel" paper by Ole Gulbrandsen (http://jcgt.org/published/0003/04/03/paper.pdf), I read that it is fully reversible:
(section 2.3.2): for all r,g ...
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Writing data to a shader resource at runtime in DX12
I'm hoping to port my existing toy raytracer to a window so that I can see samples accumulate over time. And then port over to Pixar's pmj02:
https://graphics.pixar.com/library/...
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High variance in path tracing specular objects
I'm testing my path tracer for specular surfaces. Images rendered with my own code have very noisy appearance, and I think they look like variance.
I use point light and the bunny is of mirror ...
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ray-triangle intersection precision - c++
I'm building a software renderer but I think there might be some problem with my ray-triangle intersection accuracy.
I implemented the algorithm referring to ...
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Raytracing: why are the spheres in the image below appear stretched?
Some context. Above are the code and the resulting image for it in Peter Shirley's Raytracing in one weekend's book. As you can see from the code, he adds in some spheres. And yet in the final image ...
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Ray tracing implicit surfaces using Sturm's theorem
I am trying to render implicit surfaces given by a polynomial equation $F(x,y,z) = 0$ using Sturm's theorem.
Plugging the parametric ray equation $r(t) = o + td$, where $o\in\mathbb{R}^3$ is the ray ...
user9485
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Defocus blur: Computing the pixel plane distance
I'm following Peter Shirley book, Ray tracing in one weekend. In the last chapter, he talks about how to make defocus blur by using thin len approximation. His camera class accepts a parameter called ...
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why doesn't a ray hitting a sphere at only 1 point count as a hit in sphere/ray intersection?
To give context to the question, I am reading Peter Shirley's Ray Tracing in one weekend. In his code for sphere/ray intersection, when the quadratic formula returns only 1 solution, he discards it, ...
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fastest way to bucket triangles into a grid?
What is the fastest known method for bucketing triangles into an unbounded regular 3D grid?
Specifically, I need an array of buckets. Random queries (which bucket is here) are not necessary, as this ...
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How to raytrace triangular faces when camera is not at origin?
I've watched the Pixar In A Box, Maths of Rendering Tutorial on Khan Academy. I've started writing a raytracing program and have come to the point where I must solve for ...
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Compute emitted importance of a pinhole camera
In section 16.1.1 of Physically Based Rendering the authors describe how we can check, if a given ray $r$ corresponds to one starting from the film area.
They implement this check such that it works ...
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How do we approximate the integral of the measurement contribution function in Metropolis Light Transport?
In Metropolis Light Transport, we need to approximate the integral of the measurement contribution function. I've read that this can be done using a traditional approach like path tracing. However, ...
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How can we convert a probability density according to solid angle to a density according to area?
In Chapter 14.5.3 of Physically Based Rendering - From Theory to Implementation (3rd edition), the authors claim that a probability density $p_\omega$ according to solid angle can be converted to a ...
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How does Primary Sample Space Metropolis Light Transport work?
For simplicity, assume we're only dealing with surfaces which have either a Lambertian or perfectly specular material. Morever, assume that the only type of lights are area lights (i.e. surfaces with ...
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Light field rendering for 3d software?
Is there any 3d software that supports rendering an artificial scene to a light field image?
With that I mean an image capturing light from more than one point in a scene, more lika a spherical ...
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869
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OpenCL ray tracer: which is better, geometry code on device side or on host side?
I am writing a ray tracer using openCL, and following this tutorial http://raytracey.blogspot.com/2016/11/opencl-path-tracing-tutorial-2-path.html
However, I find that the author has two copies of the ...
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Problem of understanding the coordinate systems involved in ray tracing
This picture depicts my current immagination of the coordinate systems involved in ray tracing:
Explanation:
So the green rectangle is the [-0.5, nx-0.5] x [-0.5, ny-0.5] coordinate system and you ...
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Using multiply and accumulate of 4x4 matrices for ray-triangle intersection tests on GPU
Is it possible to gain performance boost using new 4x4 MAD from NVIDIA'a tensor cores for ray-triangle intersection tests?
Really there are two questions:
Is it possible to modify some of the ray-...
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Is there ongoing research on Markov Chain Monte Carlo algorithms (other than Metropolis-Hastings) for use in ray tracing?
Metropolis Light Transport is an application of the Metropolis-Hastings algorithm. Its variants differ only in the used "mutation strategy".
Is there ongoing research on other Markov Chain Monte ...
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Bright artifacts in ray tracer rendering seemingly caused by reflections
I've been working on a new ray tracer recently, but after adding reflections I'm seeing these strange small highlights on my models, particularly on the ear of the silver rabbit below.
I've read ...
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How does a path tracer with next-event estimation work?
I am trying to implement a simple path tracer with next-event estimation in Java. The general idea is to trace a ray through the scene as usual (using a cosine distribution to determine the next ...
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Should direct illumination and path tracers render the same scene equally bright?
I am using the book Ray Tracing from the Ground Up by Kevin Suffern to build my first ray tracers in Java. Based on the theory, I expected that direct illumination and simple path tracers render the ...
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Where should the ray origin be put in perspective camera ray tracing?
Where should the ray origin be put in perspective camera ray tracing?
The following gives a picture of the ray tracing in the perspective camera setting:
https://www.cs.cornell.edu/courses/cs4620/...
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643
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how to render colored glass object?
I want to know how to deal with the color of object,Should i use diffuse reflection on the surface?
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How exactly do soft shadows get generated using a voxel cone tracing rendering technique?
Let's assume we have voxelized a scene, and all of our materials have an opacity level of 1. The reuslt would then look like:
If we raytraced the final volume that gets generated after rasterization.
...
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Self intersection artifacts in 3D image raytracing
I am developping a voxel raytracer for global illumination.
I have been successful in multiple aspects but there is a problem I am not sure how to solve.
The model works as most other Voxelization ...
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How to ensure that the raytrcing coordinate system is teh same as the projection one?
I have 2 shading models right now, one is using voxels the other one is the standard projection absed renderization method.
Putting them side by side I have noticed that no matter what I do one is ...
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Difference between BVH and Octree/K-d trees
So I'm currently reading up on acceleration data structures and so far I've heard there are 2 main schemes. Object Subdivision and Spatial Subdivision.
The Bounding Volume Hierarchy belongs to the ...
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Circular pattern aliasing in voxel ray tracer
I am doing a voxel based raytracer.
In other words, I first voxelize the scene using rasterization and I proceed to raytrace the volume in a 3D image to generate a final frame.
Currently I noticed ...
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Pathtracing line and point primitives?
So I'm in the midst of implementing a path-tracer. I have chosen to use Assimp library to load models and scene information.
According to it, it will provide mesh data and meshes may contain point, ...
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Weird artifacts in my ray tracer
I am getting weird artifacts in my simple ray tracer that I made using the book Ray Tracing in One Weekend by Peter Shirley.
Example:
(circular pattern on the ground and black tint on the spheres.)
...
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2
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Why does _ray_ tracing work?
Perspective projection (or at least non-orthogonal) is by far the most common in photo-realistic graphics. When we use perspective projection, the (equally thick) slices of volume visualized by each ...
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Tail Recursive Monte Carlo Raytracing
I am writing a raytracer in F# using montecarlo sampling
I would like to make my recursive calls tail recursive but I am not sure of this is possible with MC raytracing as one has to evaluate sampled ...
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