Questions tagged [lighting]

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3
votes
2answers
939 views

Phong: Real-time rendering of Metal and Plastic Materials

Using a shader that works like Phong, what would be the difference between painted Metal and plastic? I seem to remember reading in books years ago, that I no longer have access to, the following: ...
4
votes
3answers
351 views

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. ...
3
votes
1answer
319 views

How to send shadow rays to window light source with glazing

For rendering an indoor scene where light source is skylight coming in through the window opening, one can consider the window polyline as the light source, with the sky distribution, in direct ...
6
votes
1answer
556 views

How Sunlight is added in Bidirectional Path tracing?

How is distant directional light source(like sun) added in BDPT? If this is an indoor scene that gets sunlight through windows, how is this handled in BDPT(other than to consider Sun as a big disc far ...
7
votes
1answer
950 views

Path Tracing With Multiple Lights

I've got my path tracer working great for a single light, but I'm having trouble coming up with a solution for scenes with multiple lights. My first thought was to just send a ray to each light and ...
1
vote
1answer
124 views

Acceleration techniques for CPU soft-shadow calculation in light mapper

My light mapper can generate soft shadows just fine - for each texel I cast a ray to the light, offset by some distribution of the 'area' of the light on disc. The problem is that I am casting many ...
5
votes
2answers
262 views

Radiance at a nearly perpendicular angle is almost infinite?

As far as I understand, radiance is a measure of the "intensity" of light in a direction defined as a differential cone . It's measure is Flux per solid angle per projected area. $L = \frac{d\Phi}{d\...
2
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0answers
159 views

Picking multiple light sources from a mixture densities

According to Peter Shirely paper, one pdf(probability density function) can be defined for the union of the light sources and pick only one using a random number from this density: $$p(x) = \alpha_1 ...
0
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2answers
828 views

Energy Conservation in Lighting Equation

I am currently making a Ray-tracer as a personal project. My lighting equation looks like this ...
3
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2answers
334 views

How to adapt diffuse/GI light mapper to directional light maps?

I have a working light mapper that captures global illumination. I evaluate a hemisphere when collecting the data and store the result in the texel. However, I want to support directional lightmaps so ...
2
votes
1answer
119 views

Multiplication of SH coefficient sets representing occlusion and color

Currently I got interested in implementation of Precomputed Radiance Transfer. I decided that occlusion representation (which is not trivial to compute) would be precomputed as CPU raytracing and ...
2
votes
2answers
216 views

How does this app pull off fast, high radius HDR

I am in awe at this app I just found. It was actually one of the first things I installed when I first bought my iPad 2 but now they have updated it to add an HDR effect. I have never seen a real-...
5
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2answers
3k 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: ...
5
votes
1answer
2k views

Modern way of light sources in OpenGL?

In older versions of OpenGL there were things like: glLight(...) gl_LightSourceParameters The modern way of doing lighting is passing light source parameters manually to the shader in vao-s? Or ...
5
votes
0answers
953 views

Percentage-closer Soft Shadows implementation

I am trying to implement the Percentage-closer Soft Shadows (PCSS) from NVidia inside Unity but I am facing some issue and I don't know where they come from and then, I do not know how to solve them......
4
votes
1answer
700 views

Exponential shadow maps sampling with PCF for sampler2DShadow instead of sampler2D

I am trying to make use of free hardware PCF sampling with sampler2DShadow and extend it to more samples. So far I am sampling shadow map (...
4
votes
1answer
46 views

Are these edges a result of display color accuracy, computational accuracy, or something else?

I was messing with glowing lighting when I noticed an odd artifact in my first try. For some reason I can see three defined edges inside of the glowing pattern. I downloaded the image and marked ...
5
votes
1answer
2k views

Bloom in DirectX

How can I make an object give the effect that it is giving out light when it isn't? I basically want to make an object glow, for example Neon Lights. Also Area Lights in my engine work properly but to ...
4
votes
1answer
78 views

Is there a material that contributes to GI, but isn't directly visible?

I am doing renders of the inside of a room. I would like to show a "bird's eye" view of the room, from above the ceiling (outside the room), but still see the interior of the room. An easy way of ...
7
votes
1answer
3k views

What is Radiosity?

After reading a wikipedia article about Global Illumination It mentions a variety of techniques like Ray Tracing, Path Tracing and Ambient Occlusion. One technique it mentions is Radiosity which I don'...
5
votes
1answer
422 views

Why is spherical harmonics used in low frequency graphics data instead of a spherical Fourier transform?

I'm curious why spherical harmonics are commonly used in real time graphics instead of a spherical Fourier transform. I get that spherical harmonics are in a sort of frequency space (like FT is) so ...
17
votes
3answers
11k views

What are Spherical Harmonics & Light Probes?

What are Spherical Harmonics & Light Probes? How useful are they in computer graphics? What exactly do they do? I've heard the word spherical harmonics & Light Probes everywhere, from siggraph ...
5
votes
1answer
2k views

Alternatives to Ambient Occlusion

Recently I wanted to improve the lighting in my game engine, naturally I looked towards Ambient Occlusion. I was considering SSAO but are there any better techniques? Maybe some that are Physically ...
7
votes
2answers
3k views

Better Shadow Mapping Techniques

Currently I have basic shadow mapping setup in my engine. I am currently trying to implement something more realistic like PCSS (percentage closer soft shadows), to get a more physically accurate ...
7
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2answers
3k views

Physically Based Area Lights

So after reading https://www.guerrilla-games.com/read/killzone-shadow-fall-creating-art-tools-for-a-new-generation (a guerilla games presentation on PBR) I noticed the Area lights as opposed to the ...
0
votes
1answer
900 views

What are some new Real-Time Graphics Rendering Techniques to get closer to real life? [closed]

So recently after implementing PBR in my engine, I was wondering what are some new & old Rendering Techniques that people are implementing and researching to get Real Time Graphics closer to what ...
5
votes
2answers
265 views

Special directional light type

I am currently trying to implement a specific directional light type. This light type has been used in the game INSIDE and is called orthogonal spotlight (aka local directional light). I assume that ...
5
votes
1answer
199 views

Error with tube lighting

I have recently been working on area lights for a small open source game engine called Urho3D but have run into an issues when rendering tube lights where the lights look the same as sphere lights ...
3
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1answer
1k views

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 ...
9
votes
1answer
3k views

OpenGL specular shading - Gradient banding issues

I use Phong shading as my lighting model. Nevertheless, the specular shading produces gradients in the light cone: Hopefully you can see the gradient starting from the lower left corner expanding ...
1
vote
0answers
124 views

Can I Implement Clustered Lighting with WebGL?

Do current WebGL capabilities allow to use Clustered Lighting? If not what is it missing to allow that? Basically WebGL uses GLES 2, so is that possible with GLES 2? I want to implement this one: ...
1
vote
1answer
80 views

What does $E_L$ mean in the context of shading equations from the book "Real time rendering"?

We will use $E_L$ for irradiance perpendicular to $l$ Where $l$ is the light vector. What does this mean? How do I calculate $E_L$?
5
votes
1answer
111 views

Where are the highlight definitions inside of my shader?

I have a pretty good glow shader going now thanks to some tips from people here. However there are a few things that bother me that could maybe be better. #1 Definition of the particles A lot of ...
11
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2answers
3k views

Rendering equation - why unsolvable directly?

Why is the rendering equation, introduced by Kajiya in 1986, not solvable directly/analytically?
9
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1answer
666 views

Tweaking a glow shader to make it look better

I have a simple game and and subjects of it are these little lines. It is targeted for iOS and android so it has a HUGE range of processors that it could run on, right now. I am trying to add ...
5
votes
2answers
2k views

What is the difference between shading and shadowing?

Shading and shadowing are often mentioned in how to create realistic 3D graphics, but the distinction is not clear. Are both responsible for the generation of shadows, or do they refer to the same ...
4
votes
0answers
579 views

OpenGL ES vertex/fragment shaders - Blinn phong

I'm developing a simple educational project to study OpenGL ES. I'm try to render some simple OBJ models using Blinn-Phong. The first version of the of my implementation calculate all the lighting ...
3
votes
1answer
781 views

How to detect a screen in a photo

Is there a way to make a difference between a photo of an actual object and a photo of an object through a computer or smartphone screen. For example: how can I detect that the second image is taken ...
5
votes
1answer
918 views

How to compensate low amount of rays reaching the light in a Path Tracer

I am trying to implement for research purposes a path tracer, but so far but results are not so good and I will explain you why. The general idea before getting to the code: I am working on paths ...
5
votes
1answer
247 views

Unlit objects in deferred rendering

What is the best way to draw unlit objects with deferred? Like skybox, particles or just glowing objects? I thought about mask in alpha channel, check it in light pass and just set diffuse color but ...
4
votes
2answers
699 views

Path tracer not rendering shadows

I am trying to implement for research purposes a gradient-domain path tracer. In order to achieve this step I first need a working Path tracer. I have been creating one so far but results are wrong ...
3
votes
1answer
68 views

In what order to apply lighting and translucency?

I'm making a game that is supposed to like like a early 90s 3D game, so i'm rendering in software on an 8-bit indexed bitmap, using lookup tables for translucency and lighting. Now I have to draw a ...
2
votes
1answer
569 views

Why does my lighting look incorrect?

I have a problem with lighting calculations. I am rotating the camera around a cube which was supposed to be illuminated by the light but the resulting lighting is very weird. Check out the image ...
6
votes
0answers
132 views

Injecting Virtual point lights into 3D Grid

I am currently trying to implement light propagation volumes in DirectX 11 and I have already done the RSM part which contains position, normal, depth and flux map generation. But for Injecting ...
9
votes
2answers
1k views

How is spectral rendering handled?

Is all spectral rendering handled as simulation? Are there technique more tailored to 'consumer' rendering, such as for real-time or even just 'realistic looking without solving full physical ...
6
votes
1answer
588 views

What is the basis of rendering light caustics?

I am not looking for textbooks and related how-tos, though I'm sure they can color the answer. I'd like to understand how we handle the rendering of caustic effects — and particularly time-saving ...
4
votes
1answer
151 views

Does light particle loses energy when it hits something?

I have some material which I want to represent as a collection of spheres (atoms) and a particle of light (photon). I'm firing this particle and checking for the collision against atoms. What should ...
7
votes
1answer
3k views

Does PBR incur a performance penalty by design?

I am wondering if the various PBR models used in modern game engines for real time are heavier in terms of computation, that more classic approaches to rendering. Worded differently, is PBR just a ...
14
votes
2answers
11k views

How to Calculate Surface Normals for Generated Geometry

I have a class that generates a 3D shape based on inputs from the calling code. The inputs are things like length, depth, arc, etc. My code generates the geometry perfectly, however I am running into ...
4
votes
1answer
208 views

How can I get a spherical visibility mask map for a point on a concave surface?

I encountered this problem doing my project. Suppose there is a 3D mesh model, e.g. a human face, I need the 3D visibility map at each of the vertices of this model. By the "3D visibility map", I mean ...