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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How to implement a realtime 2D light renderer with fog/colored light on the GPU?
Since long ago I wanted to implement a 2D lightning algorithm based on an idea I saw on YouTube. The video is realtime, but it runs on the CPU and the resolution is pretty low. I'm curious if anyone ...
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Ray tracing pseudocode shadow
I don't understand the if (depth > MAX) return Black part. Does it have something to do with shadows, because in other algorithms they shoot a shadow ray towards ...
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Sphere intersection occlusion (for hybrid raytracing)
Thinking about hybrid raytracing, hence the following question:
Suppose I have two solid spheres $s_1$ and $s_2$. We know their centres and radii, and we know that they have some overlapping volume ...
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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 ...
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Shadow rays in Raytracing
After spending a few days making very little headway with a simple Raytracing program that implements Phong illumination (with shadows and no attenuation), I'm convinced I've made a logic error that I'...
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What's the current state-of-the-art algorithm for ray-tracing height-fields?
There have been lots of papers over the years on different techniques for drawing height-field terrain in a ray-tracer. Some algorithms ray-march the grid directly (or via a quadtree); others ...
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What is the difference between importance sampling and mutiple importance sampling?
I can't understand math equations. I'm a graphic designer.
What is "importance sampling"?
What is "multiple importance sampling"?
Could you explain easily, using illustrations and no math equations? ...
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Energy Conservation for Blinn-Phong BRDF
I am trying to sample from the Blinn-Phong BRDF.
For testing, I use a spherical light source (Lambertian emission) sitting on a specular plane. Here's a reference image using energy-conserving Phong ...
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Ray Transformation to Object Space for Motion Blur
My raytracer supports a wide variety of objects. To intersect them, I use the standard technique of transforming rays into object-space. This works fantastically until I add motion blur.
I model ...
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Can raytracing be used to imitate the behavior of light to a higher degree?
Raytracing "sees" the pixel on the other side of the screen;
but doesn't this mean the rays traced can be computationally reflected and refracted imitating the properties of actual light?
It'd be ...
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Problem with definition of BSDF and radiance
When I was reading theory behind physical based rendering I noticed that definition of BSDF and radiance has some problems. For example BSDF of purely specular surfaces is zero almost everywhere and ...
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Subpixel Rendering for a Ray Tracer
In font rendering, it is common to use subpixel rendering. The basic idea here is to break the pixel into its RGB components and then compute a value for each separately. Since each component is ...
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Ray Tracing with Cones: coverage, overlapping and abutting triangles
In his classic paper Ray Tracing with Cones, John Amanatides describes a variation on classical ray tracing. By extending the concept of a ray by an aperture angle, making it a cone, aliasing effects (...
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How to raytrace Bezier surfaces?
I tried this question on math.SE and surprisingly, the answer was "the equations are too nasty, just feed the function it to a numerical root-finder". But if you consider yourself "a graphics guy" ...
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Why is recursion forbidden in OpenCL?
I'd like to use OpenCL to accelerate rendering of raytraced images, but I notice that the Wikipedia page claims that recursion is forbidden in Open CL. Is this true? As I make extensive use of ...
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Radiosity VS Ray tracing
Radiosity is basically what allows this:
In a tutorial of Cornell University about Radiosity it is mentioned that:
A ray-traced version of the image shows only the light reaching the viewer by ...
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Can I raytrace gravitational lensing using only a single point source of gravity?
I'd like to simulate the magnification of very distant objects by the lensing effect of a less distant galaxy. Will I need to model large numbers of point masses or can I get away with just a single ...
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How to build a decent lens/camera objective model for path tracing?
I have written a small path-tracer after learning and experimenting on smallpt.
The only thing that I did not write (and understood) myself is how the initial rays are computed and fired from the ...
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Non Real Time Raytracing
I've played with real time raytracing (and raymarching etc) quite a bit, but haven't spent that much time on non real time raytracing - for higher quality images or for pre-rendering videos and the ...
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How are volumetric effects handled in raytracing?
How are volumetric effects such as smoke, fog, or clouds rendered by a raytracer? Unlike solid objects, these don't have a well-defined surface to compute an intersection with.
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Ray-based rendering terms [closed]
There are a number of terms for rendering techniques based on the particle model of light: forward ray-tracing, reverse ray-tracing, ray-casting, ray-marching, and possibly others. What's the ...
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What is "tiled" raytracing?
I've seen mention of tiled raytracing, but haven't been able to find much on google about it.
Can anyone explain what it is and how it works?
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Multiple Importance Sampling with more than one light
(Note: This has been cross posted from my ompf2 post.)
Recently I've implemented Multiple Importance Sampling for the sampling of surfaces in my ray tracer. I do this by, on each intersection, ...
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Speeding up convergence: am I reinventing the wheel?
I'm trying to learn about raytracing by implementing things in Python 3. I know this is always going to be slower than something like C++, and I know the speed could also be improved by using GPU ...
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Why are inverse transformations applied to rays rather than forward transformations to objects?
When computing ray-object intersections against a transformed object, most raytracers apply the inverse transform to each ray and compute the intersection against a non-transformed object. Wouldn't ...
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Am I missing something for ambient occlusion?
I'm trying to implement ambient occlusion in Python 3 and I'm seeing shadows beneath my reflective spheres but they seem very faint. I'm not sure if that means I've missed something, or if I just have ...
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How do correlated samples influence the behavior of a Monte Carlo renderer?
Most descriptions of Monte Carlo rendering methods, such as path tracing or bidirectional path tracing, assume that samples are generated independently; that is, a standard random number generator is ...
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What is Ray Marching? Is Sphere Tracing the same thing?
A lot of ShaderToy demos share the Ray Marching algorithm to render the scene, but they are often written with a very compact style and i can't find any straightforward examples or explanation.
So ...
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How can I raytrace a scene that does not fit into memory?
If the scene to be raytraced cannot be stored in memory, then without adding more RAM to the machine it seems unrealistic to render it in a practical time span, due to the need to load different parts ...
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Can I parallelise the scene for a raytraced image, rather than just the pixels?
Raytracing an image can be performed in parallel by calculating the colour of different pixels on different machines. However, this still requires each machine to have access to the entire scene to be ...
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Modelling Young's double slit experiment
Young's double slit experiment is very simple to set up and simple to explain, but it is an example of both diffraction and interference, neither of which are modelled by conventional raytracing.
It ...
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Polarising reflection and refraction for a wrap around water surface
I want to render realistic images of water in an orbiting space habitat. The image does not need to be generated in real time, although I wouldn't want it to take weeks either. I'm looking for an ...
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Can I accelerate rendering an image from a ray cloud using a GPU?
Start with a precalculated "ray cloud" - the starting point and direction of a large number of rays, most of which will not contribute to the image. The image plane's position and orientation are then ...
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What are the side effects of biasing brightness in continuous spectrum raytracing?
I want to model rays with a continuous range of frequencies so that I can get raytraced images with colour separation on refraction. I can model a light source with a specified frequency distribution ...
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Asset creation for signed distance field rendering?
In traditional computer graphics, most 3D models are rendered by rasterizing or ray tracing against a subdivided mesh of primitives, usually triangles or quads. More recently, some real-time ...
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Why does monte carlo ray tracing perform better than distributed ray tracing?
I've heard that the quality of a monte carlo ray tracer (based on path tracing algorithms) is much more realistic than a distributed (stochastic) engine. I try to understand why, but I'm just at the ...
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