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Questions tagged [reflection]

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16 votes
1 answer
4k views

Choosing Reflection or Refraction in Path Tracing

I am trying to implement refraction and transmission in my path tracer and I'm a bit unsure on how to implement it. First, some background: When light hits a surface, a portion of it will reflect, ...
RichieSams's user avatar
  • 3,782
15 votes
1 answer
12k views

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 ...
Armfoot's user avatar
  • 615
12 votes
1 answer
358 views

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 ...
trichoplax is on Codidact now's user avatar
10 votes
4 answers
27k views

What is the difference between glossy and specular reflection?

What is the difference between glossy and specular reflection? What is their relations with BRDF?
chaosink's user avatar
  • 591
7 votes
2 answers
2k views

Fresnel equation with incident angle, n and k as input

I've seen a Fresnel equation for calculating the reflection amount at incidence angle with n and k values defined. This formula usually comes up in relation to computer graphics, but I can't find this ...
Kristoffer Helander's user avatar
6 votes
3 answers
7k views

Mirror Reflections: Ray Tracing or Rasterisation?

Are mirror-like reflections in computer graphics purely handled with ray-tracing/ray-casting techniques or are there some situations where they are achieved through rasterisation?
Will D's user avatar
  • 115
6 votes
2 answers
5k views

realtime dynamic reflections, which way to go?

I'm working on my own engine and I'm struggling to find any techniques that give okay-ish reflections in realtime on dynamic scene. So far the only technique I found that work in real time on dynamic ...
newin's user avatar
  • 363
6 votes
1 answer
198 views

fix over exposure in importance sampling in screen space reflections

I am having my first encounter with the rendering of indirect reflections in the form of screen space reflections in a game engine, but i am struggling to get correct looking results. (patterns arise ...
Sebastián Mestre's user avatar
5 votes
2 answers
4k views

Refraction in a Ray Tracer: What do with an intersection within the medium?

I am currently following a tutorial at Scratchapixel.com on refraction Here is the refract function: ...
Arjan Singh's user avatar
  • 2,511
5 votes
1 answer
419 views

Should not specular reflection on a rough surface be similar to diffuse reflection?

Different BRDFs are usually used to compute diffuse and specular reflection. Some of the most often used include for example the Lambert BRDF for diffuse reflection and the Cook-Torrance BRDF for ...
wip's user avatar
  • 1,861
5 votes
1 answer
691 views

How to choose which reflection probe to use?

I have multiple reflection cube map that's prebaked before a scene. However I am being confused as to which one to choose. I am told I need to choose "closest cube map" then use it. However it is ...
Blue Bug's user avatar
  • 321
4 votes
1 answer
1k views

How to handle specular highlights with reflection / total internal reflection in a ray tracer?

Let's say that I have a raytracer that is rendering a scene that includes a refractive object. When a ray hits the refractive object, I know that I can use the fresnel equation (Schlick's ...
Alan Wolfe's user avatar
  • 7,801
4 votes
0 answers
567 views

Normal mapping for planar reflections

Ok guys, tricky one! I'm trying to modify this Unity script + shader to include normal mapping. The tl;dr is, it uses a single texture rather than a cubemap as it is only for reflecting in a planar ...
russ's user avatar
  • 2,402
3 votes
2 answers
366 views

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 ...
Loogai's user avatar
  • 139
3 votes
1 answer
697 views

Tracing shadow rays in a scene with mirrors

In my real time ray tracer, I shoot primary rays from the eye, and at hit points, I trace to a single light source to determine if the object is shadowed or lit. Pretty straightforward stuff so far. ...
Bram's user avatar
  • 270
3 votes
1 answer
940 views

What to reproject when doing temporal filtering in stochastic screen space reflection?

I am in the middle of implementing stochastic screen space reflection based on frostbite presentation here. On page number 39, it is stated that we need to reproject the ray intersection location ...
kevinyu's user avatar
  • 493
3 votes
1 answer
101 views

Expressing a reflected ray at a point as a function of the incoming ray and the normal to the surface at that point

Said L the incoming ray (at a point $P$). $R$ is the reflected ray. $N$ is the normal to the surface at the point $P$. $\alpha$ is the angle between $N$ and $L$ (and $N$ and $R$ also). It is assumed ...
Nick's user avatar
  • 321
3 votes
0 answers
117 views

How can i achieve reflections like this?

I was in my elevator when i saw this... As you can see here that reflections are kind of stretched. What causes this? And how can we achieve something like this in computer graphics?
videogamechef's user avatar
2 votes
2 answers
116 views

Why are reflections in a spherical surface sharp, regardless of depth of field?

A question has come up recently in Blender SE, remarking on the absence of blur due to depth of field in reflections in a spherical surface. This is a real-life effect.. can anyone come up with a nice ...
Robin Betts's user avatar
2 votes
1 answer
464 views

Strange sphere reflection effects in ray tracing project. I cannot figure out what causes them

I started a ray tracing project in Python. I made a CUDA kernel and a trace() function for each pixel. It works perfectly when calculating intersections, shadows and lambert shading, however when I ...
Speterius's user avatar
2 votes
1 answer
409 views

How does Unreal Engine 5's Lumen (most likely) implement reflections?

In this YouTube video, the creator mentions that reflections in Unreal Engine 5's Lumen "work by tracing the path of light as it bounces off of surfaces in the game world." Does this mean ...
HelloGoodbye's user avatar
2 votes
1 answer
154 views

Controlling "zoom" and "position" of a cubemap in shaders

I am trying to mimic reflections in image composition using shaders. I have gotten this far: In this image the floor is "reflecting" the back wall, however the reflection is uncanny because the ...
Makogan's user avatar
  • 1,726
2 votes
0 answers
66 views

Fresnel and light reflection/refraction

I keep reading about fresnel and there is one thing I don't fully understand. My understanding : Here is my understanding so far, so please correct me where I am wrong. Fresnel is related to ior (eta)...
LeXav's user avatar
  • 23
2 votes
0 answers
592 views

Calculating intensities of Virtual Point Lights in Instant Radiosity from IES lights

Short introduction I created a function that interpolates the IES luminious intensities (candelas) using Hermite interpolation, so in my code all light sources have $I(\theta, \phi)$ function - but ...
George Wilson's user avatar
1 vote
1 answer
583 views

How does notch's new graphics engine work?

@notch has recently been posting on an engine he is developing. He claims that it is voxel-based and supports deformable terrain, with a render distance of almost 1000 000 voxels and real-time ...
Tau's user avatar
  • 121
1 vote
1 answer
94 views

Finding all possible reflection matrices for a given Wythoff construction

As a pet project, I'm trying to build a small app that visualizes 4D polytopes. I want to use the Wythoff Construction method, where the shape is generated kaleidoscopically by the interaction of 4 ...
russ's user avatar
  • 2,402
1 vote
1 answer
1k views

Which technique is fast to generate real-time reflections?

I want to know about some technique with which i can generate nice reflections on the surface. I know one conventional technique where we invert an object and render it and blend it with the floor but ...
videogamechef's user avatar
1 vote
1 answer
452 views

Understanding material .mtl files

I am reading this piece of documentation to understand mtl files So far I am stuck trying to understand the difference between ambient, diffuse and specular reflectivity (Ka, Kd, Ks). If I am ...
Makogan's user avatar
  • 1,726
1 vote
0 answers
50 views

BlinnPhong sphere edges look worse than Phong. Am I doing it wrong? (code and pictures included)

First of all, I am completely new to this so please excuse me if this is a dumb question. I am following the book Real-Time 3D Rendering with DirectX and HLSL, for now implementing shaders in Nvidia ...
egil87's user avatar
  • 11
1 vote
0 answers
213 views

Normal mapping should affect specular reflections?

I'm asking this question on behalf of a friend so can't provide any images for now. The problem is to simulate a car paint material with some flakes or graininess in it. This is first done in blender ...
gallickgunner's user avatar
1 vote
0 answers
58 views

Why Screen Space effects flicker?

Nowadays is less of an issue, i think SS got massaged a little bit, but you can still spot it. These happen with SS Reflections, SSAO and Bloom. When you move the camera, the effect starts to flciker ...
Matheus Lacerda Bezerra's user avatar
1 vote
0 answers
211 views

Pathtracing specular reflections vs. specular highlights

In path-tracing, is a specular reflection model like Blinn-Phong useful? Is it more accurate to render a complete reflection dependent on the objects roughness?
Orange Mushroom's user avatar
0 votes
1 answer
515 views

Which technique should be used for rendering under water images, Ray tracing or Radiosity?

Rendering is the process of computing a three-dimensional geometric description of a scene into a two-dimensional image representation that looks real. Ray-tracing and Radiosity are two of the most ...
faizan ahmed's user avatar
0 votes
1 answer
84 views

How does ray tracing handle the calculation of reflections and shadows in the presence of multiple translucent objects?

Raytracing can handle the interaction between light and multiple translucent objects in a scene by using global illumination and raytracing with volumetric effects to calculate the color of the object ...
Arunabh's user avatar
  • 103
0 votes
1 answer
82 views

light spectrum reflection / absorbation?

I would like to know how material works with respect to light. first of all, I've a lightsource e.g. the sun. The sun has a spectrum like figure1 Figure1 When an object is illuminated by the sun, how ...
Thomas's user avatar
  • 1,265
0 votes
1 answer
604 views

Converting from RGB Color Picker to Surface Reflectance

I am trying to derive the material reflectance values from a color picker tool(say MS Paint). My understanding is to first gamma decode(raise to the power of 2.2) the RGB values from the color picker, ...
ali's user avatar
  • 740
0 votes
1 answer
208 views

Factor of 2 converting radiance to irradiance

For a Lambertian surface, the radiance at a point is $$L = \frac{\alpha}{\pi}\cos\theta_i E_0$$ If we have an infinite flat surface, albedo = 1, illuminated directly normal, then we get $$L = \...
HiddenBabel's user avatar
0 votes
1 answer
207 views

total internal reflection implementation in pbrt-v3

I've been implementing a path tracer, referring pbrt-v3. However, I'm a bit confused about its implementation. Code is here. It seems when we sample to do transmission, it tests if it meets a total ...
jinglei's user avatar
  • 293
0 votes
0 answers
46 views

Understanding the BRDF Equation

I am studying the BRDF equation. From Wikipedia, the equation is as follows: I have one main question: Where does the $\cos{\theta_i}$ in the denominator come from? The denominator implies that $...
Christopher Miller's user avatar
0 votes
1 answer
116 views

How to pick values of ambient, diffuse, specular for Phong Lighting?

I have the following code in python using the vedo package ...
Probability_Sarah's user avatar
0 votes
1 answer
63 views

Realistic chainmail reflections for videogames

If I were to create a chainmail that has realistic reflections, where would I start learning about what mechanisms to use? Normal cloth seems too simple, and the reflections look bad (they have to be ...
EmmanuelMess's user avatar
0 votes
1 answer
95 views

Wrong reflection

Here is a youtube video showing my problem: youtube.com/watch?v=y8J7VhS2pkM I think I'm either doing the texture lookup on the reflection texture wrong, or the reflection or view matrix is somehow ...
Martin Gerhardy's user avatar
0 votes
0 answers
2k views

Color shading and light calculation for ray tracing

I am currently building a ray tracer and I came across a problem and confusion regarding the light calculations. For lighting, I am using the following mathematical model: Where ...
Abdullah Emad's user avatar
0 votes
1 answer
558 views

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 ...
maurock's user avatar
  • 189
0 votes
0 answers
527 views

What is a good way to do reflection and refraction in small environment for bumpy planar surface?

I am implementing a water simulation program using OpenGL. However I could not decide which technique to use for reflection and refraction. The water is wavy and there are dynamic objects around the ...
user3117189's user avatar
-1 votes
2 answers
449 views

Why does Cubemap have 6 individual textures?

I am learning about Cubemap and I learned that A cubemap is basically a texture that contains 6 individual 2D textures but my question is Why does it contain 6 individual texture ? and also I've read ...
Abhinay Singh Negi's user avatar