Now that we've seen a few examples of how GNNs work, let's go a step further and see how we can apply neural networks to meshes.
First, we use a patch that is defined at each point in a local system of d-dimensional pseudo-coordinates, , around x. This is referred to as a geodesic polar. On each of these coordinates, we apply a set of parametric kernels,
, that produces local weights.
The kernels here differ in that they are Gaussian and not fixed, and are produced using the following equation:
![](https://static.packt-cdn.com/products/9781838647292/graphics/assets/02710616-5143-41f4-8c69-626624399c19.png)
These parameters ( and
) are trainable and learned.
A spatial convolution with a filter, g, can be defined as follows:
![](https://static.packt-cdn.com/products/9781838647292/graphics/assets/010c1e88-6c90-4c7d-84a6-d3830cf9eeae.png)
Here, is a feature at vertex i.
Previously, we mentioned geodesic polar coordinates, but what are they? Let's define them and find out. We can write them as follows:
![](https://static.packt-cdn.com/products/9781838647292/graphics/assets/865efff9-b4bd-4c07-9af3-5b72ec0e4ab6.png)
Here, is the geodesic distance between i and j and
is the...