Convert GeoJSON to TopoJSON

Question

How can GeoJSON data to TopoJSON be converted?

TopoJSON files are often smaller than GeoJSON and the conversion allows you to incrementally simplify a dataset, if you wish.

Step 3: Convert the data: topojson -o output_file.json input_file.json not working!!!!!!!!!!!! — , Sep 06 '13 at 17:00
topojson -o output_file.json input_file.json works for me under 1.1.0 and 1.4.0. Perhaps you can ask a formal question on here with more info on the problem you're having? Cheers! — Jeff, Sep 06 '13 at 18:09

score 32 · Accepted Answer · edited Jun 09 '22 at 09:44

32

Glad you asked, oh handsome OP.

Install `topojson`

From the command line (Mac OSX 10.8, assumes homebrew installed):

brew install node.js
npm install -g topojson

topojson -o output.json input.json

edited Jun 09 '22 at 09:44

Glorfindel

answered Jan 03 '13 at 18:18

Jeff

1

OP is handsome, but needs to update his answer. – Matthew James Davis Feb 18 '19 at 08:42

ow3n · Answer 2 · 2020-01-31T16:35:31.160

10

The function to create a topojson from a geojson in topojson has been moved to geo2topo

npm install topojson-server -g
geo2topo input.geojson > output.topojson

edited Jan 31 '20 at 16:35

answered Mar 16 '17 at 11:59

ow3n

For me this does not work. I am getting a not recognized error when trying to run geo2topo after running npm install topojson-server – JoeBe Jan 31 '20 at 02:34
Updated the answer to include the global flag -g try it now @JoeBe – ow3n Jan 31 '20 at 16:35
thanks. This worked perfectly. It would be great if you could tell me what the difference is here? Why do I need a global flag for this whereas for other libraries I installed until now this was not necessary? What happens behind the hood? – JoeBe Feb 10 '20 at 01:51
1

Install globally if you are using a package as a command line tool and locally if it only needs to be accessible from scripts in an app https://stackoverflow.com/a/8951576/441878 – ow3n Feb 10 '20 at 11:25

score 3 · Answer 3 · answered Apr 27 '20 at 04:59

I ported the TopoJSON code from JavaScript to Python, following the exact same format Mike uses in his library (along with his +300 tests).

If you feel better with Python, just install the library by running:

pip install pytopojson

And then run:

python geo2topo.py geojson_file

You can also use a quantization parameter. Just use the -h argument to see how it works.

Let me know if this was helpful to you!

score 0 · Answer 4 · answered Sep 21 '21 at 07:59

I have found pretty good online tool for simplifying geospatial data (including GeoJSON) and export to various formats (including TopoJSON) at https://geoprocessing.online/tool/simplify-polygons/. You can upload the GeoJSON, set simplification level and export to TopoJSON. For more information on data size reduction, see this article: https://kb.geoczech.org/knowledge-base/how-to-reduce-size-of-vector-data/