Physical Gradient Descent =========================

This is code for adapting the gradient descent algorithm to run on earth's actual geometry. You can read more about this in the attached [blog post].

Running gradient descent

You'll need Python 3, and can install the dependencies with:

> virtualenv -p python3 env
> source env/bin/activate
> pip install -r requirements.txt

And run gradient descent like so:

(env)> python gradientdescent.py 47.801686 -123.709083 ~/Downloads/srtm1203/srtm1203.tif

A number of parameter tweaking options are supported:

usage: gradientdescent.py [-h] [--output OUTPUT] [--alpha ALPHA]
                          [--gamma GAMMA] [--iters ITERS]
                          lat lon tif

You can get TIF files from this [tile grabber]!

Running the visualizer

The visualizer makes AJAX requests, so you will need to serve it from a web server instead of just opening the HTML file on the filesystem. You can do that easily with Python if you prefer, which will serve the local directory:

> python -m http.server

Then access http://localhost:8000 and the visualizer will start. You may have to update the key used inside the HTML by editing the file to your own Google Maps API key.

[tile grabber]: http://dwtkns.com/srtm/ [blog post]: https://fosterelli.co/executing-gradient-descent-on-the-earth