Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [lighting]

185 questions
27
votes
2 answers

How is a light probe different than an environmental cube map?

Looking at a light probe texture, it looks like a blurry environment map. What's the difference between the two, how is a light probe made, and what is the benefit of it being blurry?
Alan Wolfe
  • 7,801
  • 3
  • 30
  • 76
11
votes
2 answers

What is ambient lighting?

Wikipedia says: An ambient light source represents a fixed-intensity and fixed-color light source that affects all objects in the scene equally. By saying "affects all objects equally" they mean all objects get the same amount of light? So if you…
Joey
  • 627
  • 1
  • 6
  • 14
8
votes
1 answer

What is a vertex normal used for?

I'm new to the graphics area, and when it comes to the light part, the concept of vertex normals confuses me a lot. First, I cannot imagine how a vertex could have a normal, and second, when calculating the reflection lights, shouldn't I use the…
ravenisadesk
  • 183
  • 5
8
votes
2 answers

How do shaped lights work?

I know how to program directional lights, point lights and spot lights. Sometimes though, people have lights that are shaped - like bars, or even a torus. How does that work from either a ray based or rasterization perspective?
Alan Wolfe
  • 7,801
  • 3
  • 30
  • 76
4
votes
1 answer

Irradiance Map Equation What is "dω"?

Link to paper : Irradiance and Incoming Radiance | lawrence.edu Using a shader to compute En Computing En as described above is a very compute intensive operation, because we have to compute the integral over the cube map for each new …
Blue Bug
  • 321
  • 2
  • 7
4
votes
1 answer

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 where I see the edges. I am just curious why they…
J.Doe
  • 1,445
  • 12
  • 23
3
votes
3 answers

Why Diffuse Light use max(N · H, 0) instead of just letting it be negative?

In Cg tuts, Diffuse Section Surfaces that face away from the light will produce negative dot-product values, so the max(N · L, 0) in the equation ensures that these surfaces show no diffuse lighting. My question is why not just leave it be…
AlexWei
  • 237
  • 2
  • 7
0
votes
0 answers

Clarification about Phong lighting model

I've read some tutorials about Phong and Blinn lighting models and tried to implement a rendered myself. To my knowledge, the basic approach consists of the following steps: calculate the vector from the current fragment to the light rayToLight…
Damiano Massarelli
  • 1
0
votes
0 answers

gradual transition of light intensity formula

Imagine I have an x value that ranges from 1-100. The light source is pointed at x=50. From points 35 to 65 I want intensity to be 1 At the ends (ie 1 and 100), intensity should be 0 What formula should be used to model the in between values…
MD Luffy
  • 101
  • 1
0
votes
1 answer

What program can bake transparent light maps?

So I have this racing game I'm trying to modify that uses lightmaps that fade to transparency for light sources. An example from the game: I've been trying to produce a similar effect but with no luck. I've tried blender but that doesn't support…
nathan miller
  • 3
  • 2
0
votes
1 answer

Blinn-Phong, GGX and half vector for light

I read a lot about lighting recently but I have (at least) one thing that remains a dark corner: The Blinn-Phong and this opengl sourcetalks about an halfway vector. My understanding: This vector is only used in Blinn Phong or derivatives but not…
LeXav
  • 23
  • 3
0
votes
0 answers

Light brightness calculation

I've implemented the Phong shading model and I would like to improve the brightness depending to the distance of the light, its spectrum, luminosity and the cameras exposure time. Each of your light sources has a position, spectrum and a…
Thomas
  • 1,245
  • 1
  • 4
  • 16
0
votes
1 answer

Understanding the diffuse component of light

I'm a little bit confused with the transition from just setting solid colors to object to involving light and its different components. For instance, the following formula $R = I K_d max(0, n.l)$ that computes the involvement of the diffuse…
Essam
  • 115
  • 4
0
votes
1 answer

How's this laser cutting effect with backlight achieved?

Sorry for the general question, I don't even know how to tag it: https://www.youtube.com/watch?v=61UkkpsASwQ In this video, the effect is such as if there were a laser cutting a shape with a light source behind it, and then the cut is closed again…
evilmandarine
  • 101
-2
votes
1 answer

What are the 3 types of light reflection from surfaces in the Phong Lighting Model?

Can someone please explain what are the 3 types of light reflection from surfaces in the Phong Lighting Model? Maybe possibly using a diagram to help me understand it better?
user9778
  • 191
  • 3
  • 7