As mobile ArcGIS becomes more popular, the need for offline capabilities is an increasing demand. Why offline?
Many think of remote areas which lack wireless connectivity as the key driver for offline ArcGIS. But poor or spotty wireless connectivity is a reality in both remote and populated areas. There is nothing more frustrating than trying to use a mobile ArcGIS app to get work done and be denied use of the app – or having to wait an eternity for the app to load – due to wireless connectivity problems.
We have stated in past blog posts
How do I take Mobile ArcGIS Apps Offline?
There are today many ways we can take an ArcGIS mobile app offline. In our last blog post What are my Mobile GIS Options?, we discussed the four key ways mobile apps can today be built: web, hybrid, native and generated native. We will advance this topic in this blog post.
The Mechanics of Offline ArcGIS
1. Download and Store Locally ArcGIS Base Maps
Base maps can include satellite imagery, vector based roads, and topography. GIS servers such as ArcGIS today have the ability to tile base maps. That is, break large images down into smaller chunks or tiles creating a seamless user experience when panning a map. This replaced older techniques where a map pan involved dynamically regenerating a map image. Pyramiding again using tiles is also part of an ArcGIS Tiled Layer, this provides a seamless map zoom. To access base maps while offline, the bundle of tiles which make up a map area of interest needs to be downloaded to the mobile device and stored in a local database. When offline a mobile application accesses the local resources in place of the remote GIS server for these tiles.
2. Download and Store Locally ArcGIS Feature Layers
Feature layers are a special kind of layer in the world of GIS. These are called Web Feature Services (WFS) in the open source world. Feature layers are point, line and polygon overlays on top of a base map. These layers are passed to applications as raw data, to be rendered on the fly by an application. That means they are map objects, allowing interaction and editing. It also means this raw layer data can be downloaded locally and rendered. As with tiled layers, when offline a mobile application accesses the local resources (in place of the remote GIS server which is no longer accessible) for this raw layer data.
3. Download and Store Locally Related Data
Feature layers are made up of geometry (x,y in the case of point data), and attributes or information about a specific feature. For example if a tree is represented on a map as a point its attributes might be genus, height, trunk circumference etc. Related data is usually stored separately from a feature in a GIS. Rules and regulation are one example of related data. So for example, at a given location on a specific day, within a certain distance of a line feature representing a river, what are the rules for fishing? These rules would be stored in a separate table, possibly a related table. Just like base maps and feature layers, for offline use, this related data would also need to be downloaded and stored locally on the mobile device.
Example of Mobile Offline ArcGIS
Offline Mobile ArcGIS Web App for Skiers
We are surrounded by some of the best ski areas in the country here in Salt Lake. But paper trail maps remain the common way skiers navigate the many ski areas. Mobile apps which provide interactive trail maps are rare and are often simply PDF’s. We were asked to build an interactive ski trail mobile app using ArcGIS. A key requirement was offline, due to wireless connectivity issues on the mountain. We chose to build a mobile ArcGIS Web app, using an offline library we have been helping to develop. The video below shows a demo of the mobile app.
Offline Web App Builder for ArcGIS
We are big fans of Web App Builder for ArcGIS. It provides a super flexible way to build ArcGIS web applications. That includes mobile web apps. But, as we have outlined, we see offline as an important capability of all mobile ArcGIS apps. Web App Builder does not currently support offline. We thus took it on ourselves, driven by client requests, to build out a framework like Web App Builder which is similarly based on configurable widgets but works both online and offline. We call the product the Universal Map Viewer (UMV). Widgets from Web App Builder can be ported into UMV. The demo below shows UMV in action:
UMV works on any mobile device.
Offline Mobile ArcGIS Hybrid App for Emergency Management
Emergency or disaster management demands fast reactions and access to accurate data while in the field. Mobile ArcGIS is providing new ways to take up to date, mission critical data into the field. Disasters which occur in third world countries present two key challenges to relief agencies looking to leverage mobile ArcGIS: wireless connectivity issues and addressing. Many poorer countries which have been hit by disasters have no addressing system in place: homes, hospitals, relief centers etc have no physical address. Coordinating a relief effort becomes monumental when field workers have no reference through addressing. We started work on solving both of these challenges. Building a mobile ArcGIS app which works offline and uses a new universal addressing system from an innovative British company named what3words (w3w). The addressing system developed by w3w breaks the world into 3 m squares and provides a 3 word address for each square. A demo of the app can be seen below:
This is a hybrid ArcGIS mobile app, or an application generated from a mobile web app. Hybrid apps can access native code, in this case the w3w Java code for addressing. The same version of this app can be generated for Apple, Android or Windows mobile devices.
Collector for ArcGIS
Collector is a native ArcGIS mobile app released by Esri. There are 3 development teams in place at Esri, each building different versions of Collector: iOS, Android and soon to be released Windows. This is a focused data editing mobile app. It provides the ability to select an area and download base maps and feature layers for online and offline editing.
Additional capabilities such as routing are provided by ‘chaining’ Collector to other native mobile apps such as the new Navigator for ArcGIS. Chaining allows Collector to open other complimentary but separate mobile ArcGIS apps.
Offline can now be built into Web, hybrid and native ArcGIS mobile apps. We would argue offline is essential for any and all mobile ArcGIS apps. As mobile ArcGIS becomes more popular, there will be greater demand for offline. In this post we have outlined some of our work with offline, helping to demonstrate the many options now available to take ArcGIS mobile apps offline.
Contact us for more information on 801-733-0723.