# Tag Info

## Hot answers tagged physics

Accepted

### What explains the high specularity of metals?

Warning: I am not a physicist. As Dan Hulme already explained, light can't travel through metals, so dealing with IOR is a lot more... complex. I will answer why that happens and how to calculate the ...
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### Why does the 1/r² term appear with point sources?

The concept of a point source is an approximation. Physically, light sources are extended objects and emit light from every point on their surface; but when you're far enough away (i.e. the distance ...
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Accepted

### What physical properties are “lacking” to keep this 3D scene from looking like a real photograph?

Few things, but usually this is what it takes to make the difference: 1- the material reflection at his head, he is bald, yet the diffuse texture shows color difference where the hair is, this means ...
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### What explains the high specularity of metals?

Look at the refractive index of several metals. They are all complex numbers and the math does work out when you put this into the fresnel equation: you get the expected high reflectivity at all ...
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### Can we use PhysX in WebGL?

PhysX is a C++ API and can thus not directly be integrated with the JavaScript-based WebGL. Depending on your needs, you have the following options: Use a JavaScript-based physics engine, mostly ...
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### Resulting Probabilty Density in Path Tracer for paths using Next Event Estimation

I don't have any experience with Gradient Domain Path Tracing, but here are my thoughts: There seems to be a different problem If you look carefully at the little spikes of distortion in the final ...

### Why does the 1/r² term appear with point sources?

It is the inverse square law of light for a pure point light. $E = \frac{I}{r^2}$ Where E is illuminance and I is pointance or power/flux per unit solid angle.
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### Why does the 1/r² term appear with point sources?

I'll give an intuitive idea of the reason in this answer. Once this intuitive idea is grasped, it can be easier to absorb the mathematical descriptions. Other people find it easier the other way ...

### What physical properties are “lacking” to keep this 3D scene from looking like a real photograph?

I think you identified the problem yourself in your question : it still definitely looks like a 3d model It's obviously hard to tell and subjective, but while many things are off in this picture, ...
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### What physical properties are “lacking” to keep this 3D scene from looking like a real photograph?

Hard to say because we can not see the code. Subsurface scattering might be part of that equation. I would just point out that human brains are extremely specialized in facial recognition. It has ...
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### Blackbody curve to floating RGB

The Open Shading Language has a complete implementation which is based on this source code from Color Rendering of Spectra by John Walker, according to the comments. I can't vouch for its theoretical ...
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### Rendering Hypercentric Perspective

The answer is yes. You need 2 things: View space coordinates of the object Projection function for the hypercentric perspective camera. The second one can be found in here. The overview of the model ...
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### Prove radiance contributions of deeper paths fade away

If you are asking whether: $$\int fr(...) cos\theta_1Le_1 > \int fr(...)cos\theta_1 fr(...)cos\theta_2 Le_2$$ (simplified terms from the render equation you posted above), I don't think you ...
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1 vote
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### Physically Based Shading for Diffuse surfaces

So after reading up some more research papers and the concepts of most people working in this field here and there, I've reached an answer I'm satisfied with. If someone disagrees or thinks there is a ...
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1 vote

### Rendering Equation for photons carrying flux

It'd be hell a lot easier if this were on graphicsexchange, since I can't use latex here but anyways. In the first pass of Photon Mapping you don't need to use the Flux form of rendering equation. ...
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1 vote
Accepted

### How to rotate a shape in another 3D software so that the rotation matches with the rotation in Blender?

I just had to make the following changes to [manually] change the coordinate system of FleX to the one that Blender uses: ...
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