https://github.com/doersino/gomati
A simple Google Maps tile downloader and stitcher.
https://github.com/doersino/gomati
aerial-imagery bash-script google-maps map-tiles maps satellite-imagery
Last synced: over 1 year ago
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A simple Google Maps tile downloader and stitcher.
- Host: GitHub
- URL: https://github.com/doersino/gomati
- Owner: doersino
- License: mit
- Created: 2020-03-26T18:46:59.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2021-04-05T14:40:21.000Z (about 5 years ago)
- Last Synced: 2025-02-27T17:28:56.202Z (over 1 year ago)
- Topics: aerial-imagery, bash-script, google-maps, map-tiles, maps, satellite-imagery
- Language: Shell
- Homepage:
- Size: 564 KB
- Stars: 8
- Watchers: 3
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# gomati
*A simple Google Maps tile downloader and stitcher.*
**Note: I've reimplemented (and significantly extended) this tool in Python – meet [ærialbot](http://github.com/doersino/aerialbot). Despite having been designed to power a set of Twitter bots, if you configure it to download an area around a fixed point and leave the Twitter API credentials blank, it's essentially equivalent to this tool. Notably, as it uses a threadpool for tile downloading, it's *significantly* faster than this tool.**
## Setup & Usage
Since Gomati is a **humble shell script**, you'll need `bash`, along with common command-line utilities – the only ones I'm not confident you already have are `curl` and `imagemagick`. Your package manager probably provides them.
Using this tool is as simple as **entering your desired latitude and longitude** in the source code, optionally taking a peek at the other parameters you can modify, and running:
```
bash gomati.sh
```
A more detailed **list of requirements and usage/configuration instructions**, along with a couple of tips and tricks, is **located at the top of `gomati.sh`**.
## FAQ
### Why the name?
Gomati stands for **Go**ogle **Ma**ps **Ti**les and is apparently also a [river in India](https://en.wikipedia.org/wiki/Gomti_River).
### Why did you make this tool?
Because satellite imagery [can be extremely beautiful](https://earthview.withgoogle.com), and I was looking for a way of easily downloading high-resolution satellite views of arbitrary locations such as [the center pivot irrigation farms of the American heartland](http://www.thegreatamericangrid.com/archives/1441).
### Does this violate Google's terms of use?
Probably. I haven't checked. But they haven't banned my IP for downloading tens of thousands of map tiles during development and testing, so you're probably good as long as you don't go overboard downloading a centimeter-scale map of your country.
### Morally speaking, how bad is it to violate Google's terms of use assuming I don't go overboard?
I'm not an ethicist, but consider this: Google is a stupendously profitable company that earns the bulk of its income via folks like you just going about their days surfing the ad-filled web.
### What's the maximum map size?
The limiting factor is probably RAM during the stitching step: I've grabbed an 80-by-80 tile map (that's 6400 tiles for those of you keeping track at home) of my hometown, and ImageMagick ate about 12 GB of RAM while stitching them together into a 20480x20480, 420M pixel image.
(The effectively-free Google Maps Static API [limits you](https://developers.google.com/maps/documentation/maps-static/dev-guide#Imagesizes) to 1280x1280 pixels unless you're grandfathered into a discontinued premium plan, as I've learned after building Gomati.)
### Why is this tool so slow?
Since it's a shell script, there's zero multithreading and a whole bunch of context-switching overhead, plus I made a real fancy progress indicator that's updated in a tight loop (i.e. a lot of string manipulation happens frequently). I should have implemented this in Python – and I would've, if only I had anticipated the amount of feature creep I ended up sneaking in.
(The slowness isn't an issue if you use Gomati as I indend to use it: occasionally grabbing a 100ish tile map, which takes fewer than 30 seconds. Think of at as, uh, a totally intentional rate-limiting feature.)
### How do you determine tile coordinates based on latitude and longitude?
By plugging them into the surprisingly simple [Web Mercator Projection](https://en.wikipedia.org/wiki/Web_Mercator_projection) formulas.
### How can I figure out which zoom levels are available for my location?
Either by trial and error (will always work) or via [this page](https://developers.google.com/maps/documentation/javascript/examples/maxzoom-simple) (will work until Google significantly changes their documentation).
### This thing only does satellite images, not road maps – I want my money back!
Not a question, but sure: 💵
### You know, it'd be really neat if there was, like, a Twitter bot based on this tool!
Not a question, but sure: Meet [@americasquared](https://twitter.com/americasquared).
### Something is broken – can you fix it?
Possibly. Please feel free to [file an issue](https://github.com/doersino/gomati/issues) – I'll be sure to take a look!