Sound Rendering for Physically Based Simulation Sound Rendering for Physically Based Simulation

Sound rendering for physically based simulation dating, project summary

The answer for our second problem, how to solve the integral, is a bit more tricky, because in some cases, we won't be able to solve it quickly enough.

Sound synthesis of thin-shell sound will be addressed through a set of modeling techniques model reduction, high frequency bandwidth extension and precomputed sound databaseswhile real-time constrains will be addressed using data-driven approaches.

I've omitted sound rendering for physically based simulation dating vertex shader and the variables definition and the source shader I've used is in HLSL. This project will considerably widen the number of real life object sounds that can be digitally generated, and will contribute to the young research eld of physically based sound rendering, which has the potential of becoming the next key technology of the media industry.

If you create a sphere in your favorite modeling tool and check it's wireframe you'll see what I mean. Intensity is the way to answer to that, it's the amount of flux that is going in one direction passing through a defined solid angle.

It's important to notice that we won't try to solve the full rendering equationinstead we will use the following simplified version: The double integral is solved by applying a Monte Carlo estimator on each one; this leads to the following discrete equation that we can finally transform into shader code: For a perfectly specular reflection, like a mirror, the BRDF function is 0 for every incoming ray apart for the one that has the same angle of the outgoing ray, in which case the function returns 1 the angle is measured between the rays and the surface normal.

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For our purposes we will simplify the radiant flux with an RGB highschool hook up game app, even if this means losing a lot of information.

Characteristic thin shell sounds include tearing cloth and paper, crushing cans and plastic bottles, and crumpling a piece of paper and a plastic bag. Radiance is a tricky thing to understand, as it is a combination of other physics quantities, therefore, before formally define it, we will introduce a few other quantities.

The area of the shape we have obtained is the solid angle. Get Access to the 1st Network for the European Cooperation.

Coding Labs :: Physically Based Rendering

Now we can see that the equation is simply representing the outgoing radiance given the incoming radiance weighted by the cosine of the angle between every incoming ray and the normal to the surface. To do this we project the silhouette of the object onto the surface of a unit sphere centred in the point we are observing from.

Obviously it would be too much memory consuming to have a cubemap for every point in the scene! Please note that for simplicity I'm not using the Monte Carlo integration but I've simply discretized the integral.

Sound Rendering for Physically Based Simulation

For our purposes we'll use environment maps cubemaps, although spherical maps would be more suited to encode the incoming radiance from a specific direction towards a given point.

So when we talk about radiance we talk about some amount of light going in some direction to some area. Left the radiance map, right the irradiance map Lambert rendering equation Now let's present the shader's code. In my tests it was good enough given that I've dropped the resolution of the cubemap to a 32x32 per face, but it's worth bearing this in mind if you want to experiment with it.

Quite good for a single texture read shader uh? If the ray is perpendicular to the surface it will be more localized on the lit area, while if the angle is shallow it will be spread across a bigger area, eventually spreading across too much to actually being visible.

The expertise of Columbia University in thin shells and sound rendering, complemented by the expertise of Inria in real-time sound rendering provide the optimal setting for the success of this fellowship. Irradiance and radiance are our main physical quantities, and we will work on both of them to achieve our physically based rendering.

I'll show that in a moment, but for now, let's see the results. Running this for every face of the convolved cubemap using the normal cubemap as input gives us the irradiance map.

Given infinite samples it wouldn't make any difference, but in a real case it will introduce more banding than Monte Carlo.

We can now use the irradiance map as an input for the next shader, the model shader. This reduces the whole rendering equation to a single sample from a pre-calculated cubemap, specifically: This proposal addresses this problem by generating sounds from virtual environments through physically based simulation, and focuses on a challenging family of objects: Physically Based Simulation and Rendering of Thin.

Any light source emits energy, and the amount of emitted energy is function of the wavelength. The rendering equation We can now go back on the rendering equation and try to fully understand it. Radiance components We like this formula because it contains all the physical components we are interested in, and we can use it to describe a single "ray" of light.

But if the BRDF happens to depend only on the incoming radiance, or even better, on nothing if it's constantthen we can do some nice optimization.

Translate to code So, now that we have all this useful knowledge, how do we apply it to actually write something that renders to the screen?

If we plug this into the rendering equation we get: Since in the shader we will integrate in spherical coordinates we will change the formula to reflect that.

This Action will allow the researcher to become a mature and independent, and to obtain a long term research position in Europe as a world leader in physically based sound rendering.

Virtual scenes are sonied through the ad-hoc edition of recorded sounds and their manual synchronization with the visuals, yielding limited and repetitive sounds. In addition, the researcher will receive training through research and on complementary skills, including student tutoring, teaching, dissemination, and project management.

This concludes the first part of the article on physically based rendering. This function takes as input position, incoming and outgoing ray, and outputs a weight of how much the incoming ray is contributing to the final outgoing radiance. Yet, little effort has been devoted to the rendering of sound from digital environments, compared to the phenomenal advances of visual rendering.


Currently the best model to simulate light is captured by an equation known as the rendering equation. Solid angle Radiant Intensity: Industry-related skills, such as technology transfer, research-to-product techniques and standardization will be trained through a secondment in the industrial sector at AudioGaming.

Very short and super fast to evaluate. We will see the details and introduce the correct terminology in a moment. If you have a light source that emits in all directions, how much of that light flux is actually going towards a specific direction?