Questions tagged [physically-based]

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14
votes
3answers
8k 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 ...
4
votes
1answer
251 views

Material Layering

So after reading this Unreal Engine 4 Documentation page: https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/LayeredMaterials/ (Which describes how to use material layering in UE4) ...
7
votes
2answers
2k 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 ...
5
votes
1answer
2k 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 ...
1
vote
1answer
815 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
1answer
193 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 ...
16
votes
3answers
8k views

Physically based shading - ambient/indirect lighting

I implemented a physically based path tracer after studying PBRT by M. Pharr and G. Humphreys. Now I'm trying to apply physically based rendering to real time graphics using OpenGL ES (in an iPhone ...
13
votes
3answers
3k views

Correct Specular Term of the Cook-Torrance / Torrance-Sparrow Model

For a while I have been doing some research on the topic of Physically Based Rendering. One reflection model that is mentioned over and over is the Cook-Torrance / Torrance-Sparrow model. It seems ...
10
votes
2answers
515 views

Total emitted power of diffuse area light

I am reading the book Physically Based Rendering (Pharr, Humphreys). In the chapter on lights, they talk about approximating the total emitted power of different kinds of lights. For example, a point ...
7
votes
1answer
921 views

Resulting Probabilty Density in Path Tracer for paths using Next Event Estimation

I am trying to implement my own Gradient Domain Path Tracer by following the code of this guy who already implemented it: https://gist.github.com/BachiLi/4f5c6e5a4fef5773dab1 I already managed to ...
10
votes
3answers
1k views

16bit half-float linear HDR images as (diffuse/albedo) textures?

So I been thinking about this for a while and tried to google for an answer but without any success. If all your textures are 8bit LDR images, like JPEGs, couldn't that potentially cause conflicts ...
5
votes
2answers
3k views

What are the current open problems in Computer Graphics?

I did a quick investigation about the topic but there doesn't seem a decent resource to find related problems without digging into latest CG papers (unlike CS problems you can easily find a Wikipedia ...
11
votes
1answer
675 views

Compensation for energy loss in single-scattering microfacet BSDF models

Single-scattering microfacet-based surface models like the original Torrance-Sparrow BRDF or derived models like the BSDF for rough dielectric surfaces by Walter et al. neglect inter-reflection of ...
5
votes
1answer
189 views

Questions about Preconditioning Conjugate Gradient method in Baraff & Witkin 98?

I encountered some problems when implementing the cloth simulation algorithm from Baraff & Witkin 98's Large Steps in Cloth Simulation. Baraff & Witkin 98 Consider the cloth as a particle ...
6
votes
1answer
2k views

What's the difference between irradiance and fluence/radiant exposure?

A paper$^1$ I'm reading says fluence measures the incoming radiance from all directions and that fluence is similar to irradiance. It's defined by $\phi(x) = \int_{4 \pi} L(x, \vec{\omega'}) d\omega' $...
11
votes
0answers
620 views

How correct is rendering in XYZ / linear RGB space?

I have a spectral power distribution (SPD, 5 nm steps) for all light sources in the scene and SPDs for the reflectance of all surfaces under any light / viewer angle in question. I'm going to ...
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 ...
34
votes
2answers
5k views

How physically-based is the diffuse and specular distinction?

The classical way of shading surfaces in real-time computer graphics is a combination of a (Lambertian) diffuse term and a specular term, most likely Phong or Blinn-Phong. Now with the trend going ...
14
votes
2answers
1k views

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 ...
9
votes
1answer
651 views

Modelling Young's double slit experiment

Young's double slit experiment is very simple to set up and simple to explain, but it is an example of both diffraction and interference, neither of which are modelled by conventional raytracing. It ...
12
votes
1answer
312 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 ...

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