Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [lighting]

177 questions
27
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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
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Why are normal maps blue and purple in color?

I am learning about normal mapping. I understood that RGB values are converted into XYZ, but my question is how is it converted and why is the normal map blue and purple in color?
Abhinay Singh Negi
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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 presentations to blog posts. Recently Matt Pettineo…
Arjan Singh
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15
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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 camera. I got the principle right, but I'm looking…
teh internets is made of catz
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2 answers

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 trouble when calculating the surface normals.…
joshwbrick
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13
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For shader math, why should linear RGB keep the gamut of sRGB?

sRGB is often contrasted with "linear RGB." Images are stored on disk and passed to displays in sRGB, which is approximately perceptually uniform in intensity. Shader math is done in linear RGB, which is physically uniform in intensity. Gamma…
Maxpm
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12
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How is screen space ambient occlusion implemented?

I do not understand the explanation from wikipedia. For every pixel on the screen, the pixel shader samples the depth values around the current pixel and tries to compute the amount of occlusion from each of the sampled points. How can depth…
Joey
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11
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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
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Efficient rendering with many light sources

To render a scene with a single light source using phong shading, one can calculate the final color of each fragment passed into the fragment shader based on the ambient/diffuse/specular components of both the material and the light source. This can…
es1024
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Rendering equation - why unsolvable directly?

Why is the rendering equation, introduced by Kajiya in 1986, not solvable directly/analytically?
Blongphong
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10
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What is "Object Space Lighting"?

Looking at Star Swarm, a demo for the Nitrous engine, I found this little line: "Nitrous uses Object Space Lighting, the same techniques used in film, including real-time film-quality motion blur." I tried looking around for anything on "object…
Ethan Shulman
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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 equations'? I'd like to understand how we handle the…
New Alexandria
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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 along the cuboid. Here is the shader code that…
enne87
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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 realtime glow to them for two reasons I am trying to…
J.Doe
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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 different way to organize one's rendering pipeline,…
teh internets is made of catz
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