s reveal.js - The HTML Presentation Framework

Offline Mobile Map Solutions

Nick Peihl, San Juan County

npeihl.com / @npeihl

About San Juan County

Total Population: ~16,000

San Juan

Orcas

Lopez

Shaw

Others

picture: Camel credit:KnowItSome CC BY-SA 3.0
picture: Bactrian Camel Smiling credit:frted CC BY-SA 2.0

Getting to the islands

picture: Kenmore Air Cessna Grand Caravan credit: Michael Hays CC BY-2.0
picture: Samish credit: Snowy Ferries CC BY-SA 4.0

Case Studies

Case Study 1

Public Works needs to collect data points from several locations in field

Assets

  • Android phones w GPS
  • Aerial Imagery TMS (2013)

Limitations

  • No mobile data service
  • Low storage space
  • No mobile app dev

Solution

Geopaparazzi

Geopaparazzi

  • Open Source App
  • Collect GPS locations and paths
  • Reads MBTiles

MBTiles

MBTiles is a specification for storing tiled map data in SQLite databases for immediate usage and for transfer.
Details

.mapurl files


url=http://tile.openstreetmap.org/ZZZ/XXX/YYY.png
minzoom=0
maxzoom=19
center=11.42 46.8
type=google
format=png
defaultzoom=13
mbtiles=defaulttiles/_mapnik.mbtiles
description=Mapnik - Openstreetmap Slippy Map Tileserver
parameter details

Tiled ArcGIS Service example


url=http://sjcgis.org/arcgis/rest/services/Basemaps/Aerials_2013_WM/MapServer/tile/ZZZ/YYY/XXX
minzoom=10
maxzoom=19
center=-123.0 48.5
type=google
bounds=-123.395004 48.354880 -122.417221 48.749851
format=jpg
defaultzoom=13
mbtiles=defaulttiles/_sjc-aerial2013.mbtiles
description=San Juan County WA Aerials 2013

Workflow

Before leaving office...

  1. Add .mapurl file to device
  2. Open Geopaparazzi and load .mapurl source
  3. Pan to location(s) for field work
  4. Zoom to all levels in location(s)
  5. Tiles are saved on device for offline use

Advantages

  • Very stable app
  • Small storage footprint
  • Fairly easy setup

Disadvantages

  • TMS must be Slippy Map specs (Web Mercator)
  • Pre-cache all locations
  • Limited to single visible tile source (issue 286)

Case Study 2

Appraisers from Assessor's Office getting lost in field

Assets

  • iPad Air w GPS & 64GB
  • Aerial Imagery TMS
  • Reference Overlay TMS

Limitations

  • No mobile data service
  • No mobile app dev

Solution


MBTiles GPS

Portable Basemap Server

But I don't have admin access


var tilelive = require("tilelive");
require("tilelive-http")(tilelive);
require("mbtiles").registerProtocols(tilelive);

var template = "http://tile.openstreetmap.org/{z}/{x}/{y}.png";

var scheme = tilelive.Scheme.create("scanline", {
  minzoom: 12,
  maxzoom: 15,
  bbox: [-122.578926,47.509548,-122.051926,47.684575]
});

var copyTask = new tilelive.CopyTask(template, "mbtiles://./osm-sea.mbtiles", scheme);
copyTask.formats = ["tile"];

copyTask.start(function(err) {
  if (err) {
    throw err;
  }
});

copyTask.on("progress", console.log);
copyTask.on("finished", function() {
  console.log("Done!");
});
tilelive-http

DON'T

BE

EVIL

Adhere to usage restrictions and licenses

Limit your bbox and levels


/* DON'T DO THIS */
var scheme = tilelive.Scheme.create("scanline", {
  minzoom: 0,
  maxzoom: 19,
  bbox: [-180,-90,180,90]
});

var copyTask = new tilelive.CopyTask(template, "mbtiles://./all-the-things.mbtiles", scheme);
copyTask.formats = ["tile"];

copyTask.start(function(err) {
  if (err) {
    throw err;
  }
});

copyTask.on("progress", console.log);
copyTask.on("finished", function() {
  console.log("I've taken over the world!");
});

MBTiles GPS

Advantages

  • Countywide offline tiles
  • Multiple tile sources visible
  • No prep work

Disadvantages

  • TMS must be Slippy Map specs
  • Unstable app
  • Moderately difficult setup

Questions?