BlairCurrey / lake-generator

Generating lakes with perlin noise

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This program procedurally generates images of lakes from the noise package and the included filters. I was originally inspired by this blog post about procedurally generating islands.

But... why?

I have always been interested in the creative powers of computing. When I was younger, I enjoyed playing with different simulators and games with procedural generation. Delegating creative powers to a computer affords a privileged position - you can control the process but escape the minutiae. Even though you define everything you can still explore the results with curiosity and enthusiasm.

In addition, I spent my formative years in Minnesota, Land of 10,000 Lakes, where I escaped up north to the BWCA as often as possible. I think this project is an expression of that same desire to explore.

From a more technical perspective, it offered a good opportunity to explore the numpy library, especially matrix operations, and image processing.

This was probably my first independent project and I have since returned to improve it. The difference is dramatic. I have applied what I've learned in terms of object-oriented design and analyzing algorithms. I wrote an article about this process on my blog. To summarize, the code is much better encapsulated, more user friendly, and about 90% faster.

How does it work?

All the inputs are defined in the config.ini file. Documentation for these settings can be found in Config.py. This makes it easy to change parameters from a text editor.

Perlin noise, to oversimplify it, is a way to generate "smooth" random numbers. Here is a proper explanation.

The process starts with initializing the matrix and filling it with noise values according to the noise parameters defined in config.ini. These will fall between -1.0 and 1.0. That gives us something like so:

noise-img

The image looks weird (unlike "normal" perlin noise) because it's range is between -1.0 and 1.0. We will constrain it to 0.0 and 1.0, but first we will apply our filter (defined in config.ini, or else a random one), which ensures there is some sort of "lake" shape. Here is our matrix less the filter, followed by the filter in use:

filtered-img filtered

Now we will normalize the range so that all of our number fall between 0.0 and 1.0. Darkest is 0.0, lightest is 1.0.

height-img

At this point we can assign certain colors to elements that fall within a certain range. For example, everything below 0.28 will be the deepest level, so it will be set to dark blue. This gives us our final image.

lake-img

In addition, it saves a copy of the config.ini so that you can see what configuration was used and some statistics in JSON.

{
    "low": {
        "value": 880,
        "location": "(522, 1612)"
    },
    "high": {
        "value": 935,
        "location": "(302, 2034)"
    }
}

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Generating lakes with perlin noise


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