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.

230 questions
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I'm in the process of writing a Ray Tracer using DirectCompute / HLSL. First, eye rays are generated (one per pixel). Then, rays are traced, shaded and reflected in a loop. Also, shadow rays for each ...
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Path weight for direct light sampling

I originally wrote a pathtracer that just bounces by the BRDF and each sample is added to a buffer that divides by the current number of frames. Now I'd like to do next event estimation at each ...
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How to rasterize a line when the background color is not always white?

I've to rasterize a line taking into account not only the background color of the screen, which is white, but also the color of other objects in the scene. In my case, I've just another object, a ...
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Books to learn Ray Tracing [closed]

Recently I have developed and interest in Ray Tracing and like most computer graphics tutorials online there is nothing regarding implementation for a beginner like myself. So far I have only done ...
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How is Anti Aliasing Implemented in Ray Tracing?

After reading a few articles online I am can confidently say I am clueless on how Anti-Aliasing works when Ray Tracing. All I understand is that A Single Pixel/Ray is split into 4 sub-pixels and 4 ...
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How are the colors for each pixel from a Ray Tracer stored in an Image?

I have begun learning how to create a Ray Tracer and 1 thing I am confused about is how the pixel color from a Ray Tracer is stored into an image. Do we use SetPixel...
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Why if we rotate an object by R and then translate it with T, from the object perspective, we're actually applying $-T$ and then $-R$

I've been introduced to local coordinates in contrast to the global ones which I was used to work on, where we have basically the camera at the origin. For example, I've the following picture of a ...
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Should ideal specular multiply light colour with material colour?

Ideal specular reflection is like a perfect mirror. I'm looking at the code to SmallPt and see that one of the spheres has an ideal specular material: ...
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Should I use nonsymmetric BSDF for refraction in BPT?

I'm implementing bidirectional path tracing. I want to simulate perfect refraction. I read in the Veach thesis that a perfect refraction BSDF is non-symmetric. Does it mean that I need to use ...
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Is there a method to do ray marching style modulus repeat with raytracing?

One of the features of ray marching is that you can use modulus to repeat shapes infinitely, like in the image below, which is from https://www.shadertoy.com/view/MsBGW1 I was curious if there exists ...
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Solid angle and surface area values in (photometric) raytracing

So, I started writing my second raytracer - this time focusing on photometric rendering that uses IES lights and standard photometric units. I've got the basic raytracing up and running (using pure ...
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Ray tracing scene with 2 lights and sphere

I'm writing my implementation of ray tracer and I've got result which you can see at this image. So you can see that some dark parts are overlapping. And I have them even in the part where it should ...
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Controlling reflection and refraction with material properties in ray tracing

As tutors for this year’s programming languages course during our Computer Science studies we’re preparing for the students final project which is the implementation of a ray tracer. We’re ...
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Changing colors after raytracing

Intro Maxwell Render has a feature called multilight, where one can ray-trace a scene with multiple light sources, and change the brightness of the individual light sources afterwards. Luxrender has ...
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Ray casting in fan configuration produces point cloud with curvature, how to eliminate curvature?

I'm attempting to perform an intersection test using ray casting (not sure if correct term so please forgive me if not) and am outputting the intersections as a point cloud, and the point cloud shows ...
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Estimating the area of a triangle-circle intersection

I am trying to implement Ray Tracing with Cones (Amanatides 1984). Instead of rays, cones are shot into the scene and intersected with geometry. Since multiple triangles can occupy the cone's aperture,...
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Rendering equation - why unsolvable directly?

Why is the rendering equation, introduced by Kajiya in 1986, not solvable directly/analytically?
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Total emitted power of diffuse area light

I am reading the book Physically Based Rendering (Pharr, Humphreys). In the chapter on lights, they talk about approximating the total emitted power of different kinds of lights. For example, a point ...
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Components that can be used for 3d shadow analysis, sunhours of surfaces throughout the year in a 3d model?

I want to develop a component for 3d shadow analysis of 3d city model. I decided to use ray tracing for this purpose. For every time step (for sun's dynamic position during the year) rays will be sent ...
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How to convert image results into data?

I have made an 3d solar exposure analysis for a 3d city model that determines how long a surface receive direct sunlight throughout the year. Results are coloured surfaces and legend of coloures that ...
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What is the effect of the BRDF denominator?

I was reading a paper on BRDF. I've come across this formula : $$f(\omega_i, \omega_o ) = \frac{FDG}{4(N.V)(N.L)}$$ The (N.L) term can be cancelled by the cosine term which appears in the rendering ...
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What effects does path tracing capture that recursive ray tracing does not?

So I have been wanting to make a rendering engine as a summer project. I'd like to shoot for photo-realism of static scenes rather than real time dynamic game like graphics. So in my research I came ...
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Why does the 1/r² term appear with point sources?

I'm currently reading some books on radiometry. They mention that radiance is constant along a ray. It doesn't change with distance. However, I've seen some raytracer and they put the 1/r² factor when ...
681 views

How does everyone count “Rays per Second”?

Recently I'm developing a Monte-Carlo path tracer. To measure my tracer's performance, I decided to implement a simple mechanism to count how many rays can it trace in a second. Then here comes the ...
668 views

How to implement Constructive Solid Geometry in ray tracing with implicit surfaces (spheres)?

What I'm trying to do is to simulate refraction through biconcave lens described by spheres A, B, ...
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How can I resize a rendered ray traced image?

Say I have rendered an HDR ray traced image with dimensions 1920x1080 (width x height) pixels and I want to instead represent it with dimensions 960x540. Assume as well that the image has not yet been ...
148 views

Creating an Object Orientated Bounding Volume

I'm attempting to test out the maths behind bounding volume algorithms (prior to ray tracing) using MATLAB. So far, I have successfully created the relatively trivial axis aligned bounding volume, ...
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Ray-tracing the Cornell Box results in really inconsistent image

So I have a vector of glm::vec3 containing the triangles for the classic Cornell Box called triangles. The Draw method casts a ray for each pixel on the screen and ...
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Could we dispense the near clipping plane?

Would it be, at least theoretically, possible to render without a near clipping plane? Could raytracing ignore this perchance? Quite many budding 3d artists have a WTF moment the first time they ...
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BRDF and Spherical coordinate in ray tracing

I developed a ray tracer that use standard phong/blinn phong lighting model. Now I'm modifying it to support physically based rendering, so I'm implementing various BRDF models. At the moment I'm ...
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The meaning of early ray termination and front-to-back traversal in ray tracing

I'm new to computer graphics. These days I've been trying to understand how ray tracing using an acceleration data structure works. I came across the term "early ray termination" several times, I ...
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Ray-triangle intersection algorithm not intersecting (C++)

I've been trying to implement the Moller-Trumbore ray-triangle intersection algorithm in my raytracing code. The code is supposed to read in a mesh and light sources, fire off rays from the light ...