Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [ray]

19 questions
15
votes
4 answers

How is Anti Aliasing Implemented in Ray Tracing?

After reading a few articles online I can confidently say I am clueless on how Anti-Aliasing works when using Ray Tracing. All I understand is that A Single Pixel/Ray is split into 4 sub-pixels and 4 rays rather than 1. Could somebody please explain…
Arjan Singh
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5
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1 answer

Dealing with interpolated normals within a raytracer

I am trying to render a teapot within a simple raytracing that can handle reflection, refraction, and shadowing from point and directional lights. I am very confused about one detail of the raytracer and that is the interpolated normals. This…
CalebK
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4
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3 answers

What's the concept of "Ray" really?

I'm learning Ray Tracing using this MIT tutorial. I've heard Ray Tracing only in the context of lighting. I.e. I understand that ray casting is used to light an object that has been already drawn. However, I've also seen ray casting in the context…
mavavilj
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4
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0 answers

How is glint rendering done in Ray Tracing?

How is glint rendering done with ray tracing in the photo below? Is it just a simple normal map? I found a paper online that describes the exact same method used in the photo above but I have no idea what's going on, especially with all the…
Arjan Singh
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4
votes
3 answers

Student-friendly ray-triangle intersection

I'm teaching a computer graphics course, and would like to give my students a function for calculating ray-triangle intersections (not just the point of intersection, but also the uv coordinates within the triangle). This seems like a good…
TomKern
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3
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0 answers

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 pbrt-v3 without some components which I think have little influence on the intersection…
jinglei
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3
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1 answer

Classify acceleration structure using surface area heuristic

My professor gave me the following example exam question: Given 4 spheres with diameter = 1. Their centers are located on coordinates (2,4,0), (4,2,0), (4,6,0) and (6,4,0), as seen in the picture below. Three different hierarchies of tightest…
Robin Haveneers
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3
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3 answers

Sending shadow rays to the sun

How is sun modelled for ray tracing rendering? Is it part of the scene, like a sphere with a centre in some far location or it is just considered as a point? Also regarding sending shadow rays to the sun, is it, again, sampling a sphere or just…
ali
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2
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3 answers

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 pixels - this rectangle is perpendicular to line…
Kamil Kiełczewski
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2
votes
3 answers

Is there a difference between window and screen in computer graphics?

I've been reading some code which setups a ray tracer and I've realized I've a doubt regarding what's a screen and what's a window in this context. Here's the relevant code using Qt: ... void CCanvas::paint() { // check if we have something to…
user4718
1
vote
1 answer

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 t (the parameter for the parametric ray through the camera and a point on the…
PolymorphismPrince
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1
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1 answer

Expected visibility

I want to extend the following to work on a solid angle: Suppose we have a volume filled with small surfaces. If we cast a ray from a given point, the probability that the ray will not hit a surface (i.e. is visible to the sky) is given as $P(ray\…
Stackmm
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1
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0 answers

What should be considered the origin of a ray used for object picking with perspective projection

I need to create a ray to pick objects in 3d environment using cursor. I'm not going to go into detailed math for this question. There's tons of information on that. In short terms, for orthogonal projection we accomplish this by taking the cursor…
Lenny White
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0
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1 answer

Reading thesis on cone tracing, did the author make a mistake?

I am reading this document that talks about signed distance field rendering. In that document section 6.3, on the topic of cone tracing, it says: Cone tracing is an extension of the sphere tracing algorithm. In addition to the ray, a cone is…
Makogan
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0
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1 answer

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 based algorithms work. We use rasterization to store…
Makogan
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