Geo Visualizations for the Web

.. beyond Google Maps ..

Niene Boeijen

I am a web cartographer

I make maps



Back-end to front-end

Implement all through code

Niene Boeijen

Propedeuse Art Academy

MSc Geo Information Science

Internship Geo Web Visualization

Maptime Amsterdam & Utrecht

Web Cartographer

Utrecht, the Netherlands

We make interactive maps & geo data visualizations

Our expertise is open {source; data; standards}

We combine cartography with web technology

Let's talk maps!

"Everything is related to everything else, but near things are more related than distant things"

Tobler's first law of geography

Power of Maps

Our brains organize by location .. why so many relate to maps and geography is that we have no choice but to think and see spatially.

Allen Carroll

Power of Maps

Maps make sense of things

Maps lend order to complex environments

Reveal patterns and relationships

Map = Collection of Geo data

What is geo data?

geo data = data + location

Maps allow us to communicate about location using a

common framework

Coordinate system

Communicate locations & distances on the Earth's surface

Shape of the earth?

The real shape of the earth is too complex to be useful as a reference for measurement..

Geographic coordinate system

3D model

Longitude Latitude

Geographic Coordinate System:

WGS84 EPSG:4326

Lon Lat in decimal degrees


Standard way to store most geodata for the Web:


"type": "Feature",
"geometry": {
  "type": "Point",
  "coordinates": [5.2394137,52.0819662]
"properties": {
  "name": "Hotel Theater Figi"

Projected coordinate system

Mathematical projection / translation


Projected Coordinate System:

Projected Coordinate System:

Spherical/Web Mercator EPSG:3857

Square, scale not relevant, shapes important

We store data in EPSG:4326, but display it in EPSG:3857!

Why is Mercator wrong?

True Size puzzle West Wing

Projected Coordinate System:

RD New EPSG:28992


Reading materials:

EPSG 4326 vs EPSG 3857

The Google Maps spherical mercator projection

Getting my map to the web?

Analogue paper maps Digital maps Web Maps
Data Tiles, styles and servers
Print On the computer View in a browser
Hold and fold Calculate, analyze Scroll, pan, zoom

What kind of map?

  • Static & Dynamic map
  • Web GIS application with analytical tools
  • Animated, real time, data driven
  • Download
  • Infographic, image, video, gif

user driven or maker driven?

Open Geospatial Consortium - OGC standards

  • WMS Web Map Service
  • WMTS Web Map Tile Service
  • WFS Web Feature Service

Defacto - Community standard

Tiled web map

a little History

Digital maps

GIS software

GIS on the Web is not user friendly..

1996 Mapquest first with a web service!

But really slow to load..,

in 2004 Endoxon found a way for quick online mapping!

2005 Google Maps took over!

The solution?



All tiles size 256x256 pixels

Placed in a grid, sharing boundaries

Seamless map

Slippy maps, Google/OSM (XYZ) - TMS - QuadTrees (Microsoft)

All these little tiles load way faster than one big map!

Zoom levels

Each zoom level has its own set of tiles!

Zoom level 0: 1 tile for the whole world.

Increases exponentially...

Zoom level 1: 4 tiles

Zoom level 2: 16 tiles


Map with tile bounds

Serving tiles

Tiles are just images on the web



Tiles are styled and rendered in advance

Styling tiles

styling per zoom level

Lot's and lot's of geo data!

SLD & Mapfile styling..


Disadvantages Raster Tiles

No interaction with objects

No information available about objects

Multiple visualizations = multiple tile sets

Vector Tiles

the newest technology!

From Raster to Vector

Vector Tile

Arrays in a 256 x 256 matrix

Same tiling schema as Raster png tiles.

Binary format

No colours

Simplifies geometries

Advantages Vector tiles

Rendering is done on client side

Custom styles on client side

Small tile size. Fast

High resolution.

Direct access to feature information.


the rendering happens in your browser with the help of your device's graphics processing unit (GPU).

+ rotating and tilting the map (3D)

+ smooth/infinite zooming

WebGL is widely supported in modern browsers

raster tiles

vector tiles


  "version": 8, 
  "name": "Mijn eigen Stijl", 
  "sprite": "url", 
  "glyphs": "url/{fontstack}/{range}.pbf", 
  "sources": {...}, 
  "layers": [
    "id": "background", 
    "type": "background", 
    "paint": { "background-color":"#FFFFFF" } 

Interactivity with JavaScript!

( ^ this is CSS )

Alright. Fun.

"But I can't read those labels! Where are my reading glasses?"

To the front-end!


puts it all togehter

tiles, content, interaction

a map is a lot!

  • Map Interface and Interaction
  • Zoom, panning, clicking etc.
  • Map events
  • popups markers
  • Tiles (raster/vector) as Base Layer
  • Additional Data
    • File (GeoJSON)
    • WMS,WFS
    • Tiles

JavaScript Libraries for Mapping





ArcGIS Javascript API





Google Maps API

When to use what?!

D3.js for data driven info graphics

Turf.js for geospatial computation in the browser

Leaflet.js for simple light weight raster web maps

OpenLayers for more elaborate raster web map with more functionality

ArcGIS Javascript API if your client uses ESRI software

MapboxGL.js for vector tiles

Tangram for vector tiles

CARTO and Mapbox for cloud solutions

HERE Maps and Google Maps API for navigation, google services and commercial goals

Main considerations

Open source vs closed source

Mobile vs desktop

Raster vs Vector

Amount of Interactivity or GIS functionality

Amount of data to show

Let's look at:

Leaflet for Raster tile maps

MapboxGL.js for Vector Tile maps

D3.js for static maps


An Open-Source JavaScript Library for Mobile-Friendly Interactive Maps

simplicity, performance and usability

Developed by: Vladimir Agafonkin.

Weighing about 38 KB of JS.

Has all the mapping features most developers ever need.

Can be extended with Plugins

Well documented

What Leaflet does not do:

Provide data for you.

Provide the basemap.

Its not GIS

Leaflet is a framework


Base Layer


Data Layer / Feature Layer


Raster tile base map providers

Overview Leaflet providers

PDOK Basemaps

let map ='map').setView([51.505, -0.09], 13);

L.tileLayer('http://{s}{z}/{x}/{y}.png', {
  attribution: '© OpenStreetMap contributors'

Adding data layers

WMS, WFS (slow)


let marker = L.marker([52.372825, 4.900321]).addTo(map);

// ADD a WMS layer
let cbs = L.tileLayer.wms('', {
  'layers': 'cbs_buurten_2018',
  'styles': 'wijkenbuurten2018:wijkenbuurten_thema_buurten_gemeentewijkbuurt_percentage_eenpersoonshuishoudens',
  'srs': 'EPSG:28992',
  'format': 'image/png',
  'transparent': true,
  'opacity': 0.5




Use EPSG:28992 > Government in Netherlands obliged to use it!


Developed by:

mapbox-gl-js api

mapbox style spec

mapboxgl.accessToken = 'yourowntoken';
var map = new mapboxgl.Map({
  container: 'map-container',
  style: 'style.json',
  hash: true, 
  zoom: 11, 
  pitch: 60, 
  bearing: 62.4,
  center: [ 4.8, 52.4] 


  "version": 8, 
  "name": "Mijn eigen Stijl", 
  "sprite": "url", 
  "glyphs": "url/{fontstack}/{range}.pbf", 
  "sources": {...}, 
  "layers": [
    "id": "background", 
    "type": "background", 
    "paint": { "background-color":"#FFFFFF" } 

Layers or layers ???


Data layers in tile

Style layer

Leaflet every source is a layer

Vector Tile providers

Use MapboxGL.js for

Customized background maps

Interactive data

WebGL rendering


Data Driven Documents

A JavaScript library for manipulating documents based on data

D3 helps you bring data to life using HTML, SVG, and CSS.

Developed by Mike Bostock

Allows you to bind data to the DOM and apply data-driven transformations to the document



supports large datasets

Dynamic, interaction, animation


Text-based, mathematical representation of an image.

Vector Graphics

Can be searched, indexed, scripted, and compressed!

D3 is NOT

a slippy map creator

Not based on tiles!!

Mostly used for:

Charts (pie, line), Tables, Maps, Networks, animation & interactivity

Use D3.js for

Interactive graphic map representations

Different coordinate systems and projections

From real-world to screen coordinates


Using GeoJSON or TopoJSON files




Feel like trying? >>

Maps are everywhere these days...


"There has never been more open data available than at this moment in time, and everyone from global NGOs to armchair hobbyists are using that data to create maps. "

The new cartographers, Next City

Vibrant. Dynamic. Responsive. Intelligent. We no longer have the static images, the paper-under-glass we used to have. Instead, today’s maps feel like living, breathing things – highlighting everything related to our taps and inputs, and dimming and de-emphasizing everything that isn’t.

the age of the autonomous vehicle

"The realization of the interactive map as an experience, not just a map design."

GIS is dead, long live to GIS! - Javier de la Torre

New techniques = new challenges

the cartographer

the developer


Web Mapping

More then design

  • speed and scalability
  • Data-driven
  • Responsive designs
  • Personalised

The Universal Map

How long until most of the world is using the same map?

the Universial map - Justin oBeirne

Cartography is the new code.

Mapping the Future - Wired

Cartography is not a niche anymore it has become main stream

  • Big data
  • Mass consumption
  • Open source software
  • Open data

GIS is dead, long live to GIS! - Javier de la Torre


You need to be able to find, manipulate, and store spatial and non-spatial data.

You need to be able to design a functional and attractive cartographic representation of that data as well as the UI controls to operate it.

You need to be able to implement that design through code.

Axis Maps


For cartographers to code. Data driven, user interactivity

For developers to design a good map, think spatial

All maps lie!

".. maps can visualize a lot of data quickly and effectively. But they can also visualize a lot of data inaccurately and misleadingly."

Citylab - when maps lie

Power of Beautiful maps

They stimulate both sides of our brain: the right side that’s intuitive and aesthetic, and the left side that’s rational and analytical. Maps are this wonderful combination of both.

Allen Carroll

Easy visual mistakes ..

Choropleth map, be carefull..

regions with bigger sizes tend to have a bigger weight in the map interpretation

No absolute numbers, normalize your data

Carefull with the color scale

election maps data to viz CHOROPLETH maps

No more heatmaps!

yes.. they look fancy but do not always show you the data..

Presentation: Stop using heatmaps to discover spatial patterns

Wrong classification

same data, same map, different stories

Tooo much data..

Coordinate precision

"IF you torture the data long enough, it will confess to anything."

Ronald Coase

Cartography is inherently an instrument of power

Make your map carefully

cartography and power

The future .. Are maps necessary?

Cartography in the Age of Autonomous Vehicles - Justin oBerine Are maps necessary? - Nicholas Carr

Are we there yet?

CNN travel

People just love good maps

and I love to make them!

Thank you!

Questions ?

Stay in touch!
Niene Boeijen