![]() ![]() Playing around with the values can also yield interesting results such as these van Gogh looking patterns. Depending on the values you put into the function we get the results below. The trick isn’t to do just one level of noise, it’s to offset the position being shaded by noise, and use that as input for another noise function, so if we have a noise (x,y,z) function we would do noise(x + noise(x,y,z), y + noise(x, y, z), z + noise(x, y, z)). It didn’t look anything like something one would find in space. ![]() This is what the first results looked like below. It looks too grainy for a nebula, which should be more wispy and gaseous and less cotton ball like. This creates organic looking noise, but it wasn’t quite the noise I wanted. The first thing I started with was a Fractional Brownian Motion function, which sums up several noise() functions that have a different amplitude and frequency. The points are then used as locations of spheres which are shaded using a shader I will talk about below. Now, if the next point lies within a certain radius of that point, you don’t add a new point, instead you increase the neighbor count of the point already in the list. Basically you take the first point and put it in a list. The simplest method was to make buckets based on the locations. I was supposed to make this point cloud look like nebula. The data was a point cloud of about 400k data points which just held location data. ![]() It’s a fantastic book and a great introduction to writing various shaders and working with Renderman. I’m basing the shader on the cloud shader in Advanced Renderman by Larry gritz and Anthony A. I started experimenting on a small file with three spheres. I’m going to talk about using Renderman shaders, but it can easily be translated into OpenGL or DirectX or whatever because it doesn’t use anything characteristic to Renderman. The article is concerned more with the aesthetics than accurate visualization of the data. For this article, the data doesn’t actually have to be real astrophysical data, it can be made up and it will still look good. The data that is visualized comes from the Center for Computational Relativity and Gravitation. This is part of my masters thesis which involves writing a Renderman pipeline for RIT’s visualization software called Spiegel. Today I’m going to write about making a nebula shader to make awesome looking galaxies and nebulae. ![]()
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