Chris Henrick clhenrick

This is a demonstartion of how to align arbitrary GeoJSON data to the us-atlas topojson data.

It's important to note that the TopoJSON from us-atlas has it's map projection, (d3.geoAlbersUsa), built into it. In other words, it is considered "projected" geographic data.

This is an important distinction from GeoJSON data which is most typically stored in the unprojected Coordinate Reference System WGS84, also commonly referred to as "lat, lon" (though coordinates are most often stored in the order longitude, latitude).

I had a large dataset in postgis and wanted to avoid the hassle of first exporting it to a several GB geojson file before tiling it with Tippecanoe.

ogr2ogr -f GeoJSON /dev/stdout \                                                                            
PG:"host=localhost dbname=postgres user=postgres password=thepassword" \
-sql "select * from a, roi where a.geom && roi.geom" \
| docker run -i -v ${PWD}:/data tippecanoe:latest tippecanoe \
--output=/data/yourtiles.mbtiles

Overview

Force-directed positioning based on a physics simulation can help with graph readability because it minimizes node occlusion, but it comes at the expense of precision, because both the X axis and the Y axis are compromised in favor of the simulation. As an alternative, we can position the points in some other fashion, then selectively apply force positioning to declutter the layout in specific regions when the user shifts attention toward them, such as with a mouseover.

This project is written in a heavily annotated style called literate programming. The code blocks from this Markdown document are being executed as JavaScript by lit-web.

Implementation

Setup

⚠️ this is now stupidly out of date

Computers

13" Macbook Pro 3.3 GHz i7 (late 2016)
Microsoft Surface Book (2016)

Peripherals

Dell up3216q 32" monitor

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	export PATH := node_modules/.bin:$(PATH)
	export SHELL := /usr/bin/env bash

	.PHONY: dev
	dev: check-nvm install # run `yarn dev` in .nvmrc-mandated node
	@bash -l -c 'nvm exec --silent yarn -s dev'

	.PHONY: install
	install: # install deps using yarn in .nvmrc-mandated node
	@bash -l -c 'nvm exec --silent yarn -s'

	FROM python:3.6-slim-stretch

	ADD requirements.txt /tmp/requirements.txt

	RUN apt-get update && \
	apt-get install -y \
	build-essential \
	make \
	gcc \
	locales \

	#!/usr/bin/env bash

	URI="https://services1.arcgis.com/sTaVXkn06Nqew9yU/ArcGIS/rest/services/Political_Boundaries_Feb2016/FeatureServer/1/query?&outfields=*&f=geojson&where=objectid%20is%20not%20null"

	ogr2ogr -f GeoJSON ca_assembly_districts.json $URI OGRGeoJSON

	node_modules/
	.DS_Store