Questions tagged [lighting]
The lighting tag has no usage guidance.
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Energy Conservation in Lighting Equation
I am currently making a Ray-tracer as a personal project. My lighting equation looks like this
...
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How does a path tracer capture light falloff if it deals exclusively with radiance?
My understanding is that path tracers deal with radiance because radiance is constant along a ray. You simply go through and evaluate the light transport equation:
$$
L_o(p, \omega_o) = L_e(p,\...
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What is meant by ‘NEE’ in computer graphics?
I am reading this paper [Practical Path Guiding for Efficient Light-Transport Simulation, Müller et al, 2017] and it contains the following sentence:
In practice, however, we recommend combining path-...
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Ambient occlusion depth buffer normalization
Been trying to follow a shader from A Comparative Study of Screen-Space Ambient Occlusion Methods
http://frederikaalund.com/wp-content/uploads/2013/05/A-Comparative-Study-of-Screen-Space-Ambient-...
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Problem sampling uniformly envmap with GGX
I have made a program that samples uniformly an environment map and computes the lighting using the GGX BRDF.
I have made a small example that reproduces the issue I'm having. You can check it out ...
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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 ...
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194
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OpenGL old-style diffuse shading producing unexpected effects
Question:
What is going wrong with the shape of the contours of constant illumination in the below picture ?
Detail:
Although Lambertian shading might be ill-regarded because it exposes the hard edges ...
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183
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Trying to understand how to render a volumetric point light
My goal is to render a volumetric point light as explained in this book's chapter 10: FGED Rendering
The book explains the math pretty well, but I'm not sure I understand what is the required setup ...
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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 ...
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What effects are used to light this scene?
I am interested how that image on the right of the slider (just albedo) can produce such a realistic looking scene as the scene on the left.
What effects (at a minimum) does this scene seem to be ...
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What is wrong with my metallic PBR shader?
I feel like my light conservation math isn't correct, but I am not sure which part is wrong.
Is reflected light supposed to influence the diffuse light?
Does metalness only affect the reflected ...
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Confusion about light PDF
I have a doubt regarding shape lights pdfs, specifically various sources point at the fact that the pdf is a constant:
$$
lightpdf = 1/A
$$
Where $A$ is the area of the light surface. Expressed in ...
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143
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How to simulate a line laser diode?
I'm interested in simulating the way a laser line deforms when it strikes an object and runs along the surface of it. Which concepts would be involved? Is there any 3D modeling software out there that ...
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How does the Modified Phong Lighting Model from the Phong Lighting Model?
How does the Modified Phong lighting model also known as the Blinn-Phong differ from the Phong Lighting Model?
How can I distinguish the two?
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How to interpolate vertex normals for Phong lighting when barycentric coordinates are negative?
I'm interpolating normals for Phong lighting models. Since I am calculating in the light of each pixel, I'm doing the interpolating after the viewport transform has been applied. So I save a version ...
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Different basis from spherical harmonics to represent light?
There's a lot of research being done in 3D shape analysis when it comes to PDE methods. Recently I've been reading quite a bit of literature on this subject and recent trends in this subject propose ...
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How to pick values of ambient, diffuse, specular for Phong Lighting?
I have the following code in python using the vedo package
...
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With a light source at (0,2,0) and unit cube (from [-1,1]) using a given shading formula, how is the r,g,b for each surface calculated?
The above problem is from a past Computer Graphics exam.
I am particularly confused about the explanation given, firstly for the top and bottom planes (since the direction of normal for top plane ...
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Ray light color at distance
I am obviously not understanding something related to light for a ray tracer.
Reading Spectral representation
and Point light calculation
A bit of a context:
My question is: in room at X degrees ...
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208
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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 ...
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How to improve rendering of surface water in shaded-relief images
I asked a version of this question on GIS Stack Exchange three months ago, but did not receive an answer. So I am posting it here.
I’ve written a simple Java application for rendering high-resolution ...
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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 ...
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I am trying to find a clip about the art of old computer graphics
I have saw a clip where a guy talked about the art of squeezing some nice graphics into a very small space that was available on old computers. Come to think of it, it sounded something like today's ...
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Can ambient light reflection of a surface be larger than diffuse reflection?
According to Phong's reflection model, there are different reflection constants (k) and different intensities of the light source (i) for ambient, diffuse, and specular terms:
$I_p=k_ai_a+\sum_{m \in ...
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241
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Pdf division in BRDF sampling
While following scratchapixel's tutorial on indirect diffuse implementation in path tracing, the samples gets divided by the pdf, which in case of a uniform pdf results in $1/2\pi$ so we have that the ...
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Adding specular reflections to a ripple simulation
I am following the algorithm shown in this code here. Essentially there is a simple simulation of heights and then the difference in heights on the x and y axis respectively (sampling adjacent points) ...
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Formula for non area light BRDFs
I'm reading a graphics book and it talks about BRDFs being the ratio between differential outgoing radiance and differential irradiance. The formula it gives is
f(l, v) = dL(v)/dE(l)
Where l is the ...
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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 ...
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117
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Physically realistic received irradiance values given some BRDF?
I am trying to simulate the actual response of a camera given some object that is reflecting light. I've written a ray tracer, and have a BRDF that I need to use, and I have a camera sensitivity in ...
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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 ...
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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 ...
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Ringlike artifacts produced by rays bouncing off a light source
I recently set up a (very basic) ray-marched path-tracer, and I'm getting strange surface patterns on my area light [link]. I'm using known-valid analytical normals for the light's surface, and the ...
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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 ...
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Specular Highlight Gray When Behind Model
What would cause this grayscaled backside?
When my camera is behind my model I see a grayscale specular highlight. However, in front of it is perfectly fine. Here's my shading code. (Software ...
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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?
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