Reviewing 3 Web Mapping Platforms and their Limitations

Reviewing 3 Web Mapping Platforms and their Limitations

One of my Summer of Maps projects has involved working with Ben Harold, a journalist from WHYY/NewsWorks and The Notebook to explore the spatial impact of Renaissance Schools, Philadelphia School District’s turnaround initiative. A key objective of the initiative is to transform chronically under-performing District schools through having “capable” individuals and organizations, step in and assume all operating responsibilities. Having reported extensively on the impact of the initiative on participating schools and communities, Ben approached Azavea with an interest in exploring new spatial patterns in the geography of the School District that are emerging as a consequence of the initiative. Each public school in Philadelphia has a well-defined catchment area from which students are drawn, as such, when a private organization takes over the operating responsibilities for a particular school they effectively gain “control” of the corresponding catchment area. Philadelphia’s School Finder, pictured and linked to below illustrates how the catchment boundaries work.

My task was to map the catchment areas that comprise the Philadelphia School district and to show whom has control has changed over time and give a picture of where the geography of the School District’s catchment areas currently stand.

Since WHYY and The Notebook exist primarily online, an important requirement was to create web-based interactive maps that both organization’s audiences would be able to engage with. In order to do this, I had to explore a number of web-mapping platforms to identify one that would be most appropriate for the task at hand. [Note: Because the final web maps that were created will be released in a WHYY story in October, we can’t show them here, yet. The primary purpose of this blogpost is to share some thoughts on the various web-based mapping platforms considered.] As I am not a programmer, and likely wasn’t going to become one in just a couple weeks, a main requirement of any platform I considered was that it did not require programming expertise. I started with a wish list for a platform that would provide: flexibility in cartography options, the ability to show changes over time dynamically, and cross-browser platform support on various devices. After some quick preliminary research it seemed like the three ‘best’ options given my requirements were ArcGis Online Explorer, TileMill and GeoCommons.

TileMill was the first option I explored and spent the least amount of time with. I’d seen awesome really great maps which had been created with it and while map-makers are required to use CartoCSS (TileMill’s styling language) to design their maps, learning the code for implementing basic design elements seemed very do-able, especially with the help of their reference guide. CartoCSS did prove to be fairly easy to figure out, reviewing the various guides they have and asking my colleagues a few questions made it a fairly navigable platform. Ultimately, however my exploration with TileMill was cut short by the realization that in order to add a time-enabled functionality I would need to know some javascript. This then left me with GeCcommons and ArcGIS Online. Both were fairly easy to learn.

GeoCommons is geared towards non-GIS users so its interface is super intuitive. In addition to being a tool for creating web maps that visualize and explore data, GeoCommons is a site for sharing open geographic data, and has some useful functions for data management and geoprocessing. For example, you can use it for tasks like joining spatial and non-spatial data and for converting data from one format to another.

One important function that GeoCommons offers is the ability for a map-maker to animate data with associated time variables in a map. One such example is here. This is a supposed to be a fairly straightforward process. However, I found a number of challenges. Map-makers have limited control over the settings of the animation, particularly its speed and the ability to watch an animation when viewing a map on an iPad or iPhone is absent. I also found the animation tool to be quite glitchy, it seemed to have issues reading my dates that fell on the first day of the year and always moved too fast to allow a viewer to see any final date ranges.

Beyond the challenges around configuring an animation properly, the other key problems I found when using GeoCommons were its limited cartographic and customization options. Map-makers’ have a set of predefined color options for fills and borders and don’t have the ability to control basic options like the RGB specification for a color.  The legends are also not configurable nor super responsive so attempts to distinguish particular map elements with slight differences in shading or stroke fills are often not communicated well on the legend.

The  legend to the left corresponds to a map where the stroke and transparency on Mastery High Schools is significantly thicker than on Mastery’s Elementary Schools but this legend does not accurately convey that.

Finally, GeoCommons does not allow for symbolizing data within a layer by nominal categories. One could imagine some basic work-arounds to this limitation (i.e. using numbers  to represent nominal categories in the data preparation stage) but the fact that legends are entirely not configurable makes it impossible to communicate to viewers what nominal category each numeric value corresponds with.

At the end of the day, despite the cons listed above the most important reason I opted not to use GeoCommons was that it is flash based and so users without flash installed on their device are unable to view its maps.
Similar to GeoCommons, is a tool for viewing and making maps and web applications and sharing spatial data. It is comprised of ArcGIS Explorer online and the ArcGIS map viewer. Both are interfaces for creating web maps but the choice of which to use is dependent on what you want your final output to be (i.e. a presentation or a web map that you will then configure into a web application).

The cartography options for ArcGIS Online are much broader than what GeoCommons makes available, though not even close to being as great as TileMill’s. Map-makers can not fill polygons with a pattern or adjust the look of borders beyond the color and stroke but they can at least enter specific RGB codes, an option that is not available with GeoCommons.

Explorer online maps need to be viewed with Silverlight which although free, is not compatible with Safari browsers on the iPhone or iPad.  A recent update to ArcGIS Online allows map-makers to share maps made through ArcGIS Explorer Online as presentations using the map viewer. When maps are saved and shared as presentations they can be viewed on browsers without Silverlight. This is a great work around. Another option is to publish web maps as custom applications, these can also be viewed without Silverlight.

Beyond the design of the map, the ability to show changes over time was important. Loading time-enabled layers on requires access to a GIS Server. In order for a map (with said time-enabled layers) to load when a viewer tries to access the map, the layer must  be hosted on a public facing ArcGIS server. While we do have a server set up here at Azavea, it is on our internal network. As such the process of loading the map took minutes for users not on our network. One potential work around for this is to leverage ArcGIS’s Online Presentation’s option to advance through slides without changing the geographic extent of the basemap. With a fixed extent one can have each new slide represent a new time interval and make slight changes to the information being displayed to try to convey change over time. Another option is to use one of the custom application templates that allow users to have up to three maps side by side and have each map represent a different point in time.

Despite all of the useful functions ArcGIS Online provides, one of the most problematic limitations of the web maps is that you can’t publish or share legends. While you work with the data and through the process of map-making you are able to view the legend but if you try to access a shared map via its corresponding URL you are unable to view said legend. You can enable pop-ups that describe characteristics of the polygons, points and lines included on the map but without a legend to immediately explain to viewers what they are seeing, understanding the meaning behind the map can be a challenge. The only way to include a legend used to be incorporating your web maps into customized Rest Web mapping applications that you had to build on your own. However this changed at the beginning of this year, ArcGIS Online now has a number of web application templates that include legends (which allow for customization of various elements without requiring coding).

I began my search for the most appropriate tool for creating web-based interactive maps with particular features in mind. What I found was no tool could really precisely meet all the needs I initially envisioned. Perhaps one day there will be a tool that brings together the styling options of Tile Mill with the improved easy-to-configure animation abilities of GeoCommons and the no-programming needed web app customization functions of ArcGIS Online. Or, perhaps it already exists and I just didn’t come across it? What other programming-free platforms for creating web-apps are out there and what are their limitations? Leave a comment to share!