Michael McLarnon | Azavea Journal

Articles by
Michael McLarnon

PhillyHistory.org Makes it to the iPhone

Vol. 4 Issue 3, July 2009

"We've recently decided to make some inroads to learning about and implementing mobile phone technology for several of our software applications."

Left to Right: PhillyHistory as seen on an iPhone; detail view of an historic photo; map view of historic photo search.

An increasingly hot topic in technology lately is that of mobile versions of web applications. It seems that everyone is carrying a BlackBerry, SmartPhone, or iPhone these days, and wants to be able to access all their information on the go. In response to this trend, we’ve recently decided to make an investment in learning about and implementing mobile phone technology for several of our software applications. I recently attended a workshop on iPhone development at the 2009 Museums and the Web conference, and decided that working on an iPhone-specific application would be a great way to get started. We decided to start with the Sajara-enabled PhillyHistory.org site.

Basically, developing for iPhone can take one of three forms:

Adjust an existing site. Essentially, you simply need to make sure that your current site looks good on the iPhone.
Create an iPhone specific web application. Create a new web application, but tailor it visually and functionally to the iPhone’s layout and interface.
Create an iPhone application. Write a full application (in the Objective-C programming language) and publish it through the App Store.

Each option has its advantages and disadvantages, but we decided to go with the second option, since it allows us to have a very sleek interface, without the difficulty of rewriting the application in a new language and the overhead of publishing it to the Apple Store. The main disadvantage to creating a full iPhone application is that it means that we won’t have access to the iPhone’s location SDK.

Once we chose a development route, we needed to start thinking about the user interface from a functional standpoint. I first decided to remove some of the more advanced features (such as keyword and topic searching) of the PhillyHistory site, and focus on what Sajara does best: geography-based searching. iPhone UI design generally follows a simple ‘screen-per-function’ guideline, so I decided to include three ways of accessing a geographic search: by neighborhood, by text location, or directly by map interaction.

All three tasks eventually take the user to a map view, which includes the Sajara geographically-based asset search, and shows markers for the results. The map view uses the OpenLayers API for displaying the map and markers, with some hacks and modifications for allowing the user to more easily drag the map around and zoom in and out on the iPhone. Each time the user pans or zooms the map, the new map extents are used to request a new search. Since I was mostly focusing on the redesign of the user interface, I left the logic behind the search mechanism unchanged from the logic that runs the full PhillyHistory site.

From the map, a user can select one of the markers to get the details for that asset. This screen shows the asset’s image, title, date, and other related data.

Developing the Sajara iPhone web application was fairly simple from a technical perspective. The constraints of having a small screen and keeping a touch interface in mind did make the project interesting. Additionally, one of the big advantages of developing a web app for the iPhone is that there is only one target platform, which greatly simplifies testing.

We look forward to continuing to brainstorm about possible ‘next steps’ in expanding our collection of mobile Sajara apps (and beyond). The next steps for this application and research, specific to Sajara, might include:

Enhancing the map interface to allow for pinch zooming
Supporting other devices, e.g. BlackBerry
Allow other types of searching (keyword, year range, etc.)

To experience the PhillyHistory iPhone app, please go to http://www.phillyhistory.org/i

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Mapping the Du Bois Philadelphia Negro

By Michael McLarnon Published in

Vol. 3 Issue 2, April 2008

In 1896 sociologist W.E.B. Du Bois was invited by the University of Pennsylvania and Philadelphia’s College Settlement Association to conduct a survey that was the basis for the 1899 book, The Philadelphia Negro. The survey focused on blacks living in the seventh ward, defined as the area in Center City between Spruce Street and South Street, from Seventh Street east to the Schuylkill River.

Du Bois lived in Philadelphia for a year during which he went door-to-door, interviewing each of the several thousand black households. He classified each of them by social class according to his own judgment and used colors to represent each group on a map of the seventh ward. Unfortunately, the actual individual data he collected in 1896 no longer exists. What we do have, however, is a map that he produced, showing the social class for the households in this area.

A historic W.E.B DuBois map (c. 1896) mapping data on blacks living in Philadelphia’s 7th ward.

In 2005 a group at the University of Pennsylvania’s School of Design, led by project director, Amy Hillier – Assistant Professor in the Department of City and Regional Planning in the School of Design, began collecting and mapping historical demographic and spatial data about Philadelphia’s old seventh ward at the time of Du Bois’ study. Their goal for the project, called “Mapping the Du Bois Philadelphia Negro” and funded by the National Endowment for Humanities, was to use historical data in a modern GIS system to allow scholars and students to explore the historic area of the seventh ward and the people who lived there, and perform their own analyses, in much the same way that Du Bois himself would have. Additionally, the “Mapping Du Bois” team hopes to provide valuable research tools to middle- and high-school students in order for them to more clearly understand the black experience in Philadelphia at the turn of the century.

Azavea was invited to partner with “Mapping the Du Bois Philadelphia Negro” to develop a web application that would enable the recently collected project data to be viewed and analyzed spatially by users. The application uses ESRI’s ArcGIS Server software as a mapping engine and the ESRI’s WebADF for the inclusion of dynamic maps on the web site. Click here to access the beta version of the application (best viewed in IE). A complete version of the application with even more exciting features will be released in a few weeks… so stay tuned!

The application gives students the opportunity to map many different data points, such as race, immigrant status, and household population, across the old seventh ward. Users can simultaneously view the data on modern GIS analysis map layers as well as on the historic maps Du Bois created. Development on the map is ongoing, but one of the chief challenges has been the shape of the Old Seventh Ward – it is a wide strip the cuts across the south edge of what we would now consider ‘Center City’, but is only a few blocks high. This has required a web interface that is a bit different from the norm.

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ParcelExplorer Enables Historic and Linen Maps to be Searched and Accessed Online

By Michael McLarnon Published in

Vol. 2 Issue 4, August 2007

The images above each show the same property outline with a different historic map in the background. In order from left to right: 1942 Land Use Map, 1859 Hexamer Locher Map, and the linen DOR Parcel Records Maps

If you have ever been involved in any activity pertaining to land parcel research or assessment, you know that flipping through linen registry maps –Philadelphia has 5,500 plus of these– can be a tedious endeavor. ParcelExplorer enables users to view the City of Philadelphia Department of Records’ current land parcel map layers and ato see scans of the original linen maps on which the records are based. Not only can these scanned maps be shown but potentially any scanned map could be included as possible background layers.

We recently added the ability to include several types of historical maps in the application. Specifically, we received three sets of digitized historic maps from the Philadelphia Free Library (scanned by The Athenaeum of Philadelphia). One of these sets of maps was the Hexamer-Locher atlas created in 1857-60, which was used as a fire insurance atlas. The other two sets of maps are Philadelphia land-use maps, from 1942 and 1962. (for more information go to http://www.philageohistory.org/rdic-images/). These historic maps add valuable data to the results generated from a search for the history of a particular parcel.

Along with the addition of historic maps, there are some other changes coming up that we hope will make the site even easier to use. Currently, payment for registration to the application is accepted by check only, and registration can only be paid for in six-month intervals. Plans are in the works to accept payment by credit card, which will make the subscription process instantaneous. Additionally, for users who access the application less frequently, the Department of Records will be offering payment for subscription based on hourly and daily usage.

For more information click on “Demo Button” or “Fact Sheet” at: http://citymaps.phila.gov/ParcelExplorer/

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Azavea Research: Historic Geocoder

By Michael McLarnon Published in

Vol. 2 Issue 3, May 2007

This photo states that it was taken in 1894 at the NW corner of 15th and Pennsylvania Ave.
In 1895 Pennsylvania Ave. ran along the railroad tracks that are now between Hamilton and Callowhill.
That intersection no longer exists, as Pennsylvania Ave. now ends around the intersection of 22nd and Hamilton.
We have the photo geocoded as 15th and Hamilton as that is the current address for the same location.

Most people have experienced typing an address, intersection, or other location description into an online application which then converts it into coordinates that can be used to pinpoint the location on a map. This is the part of the process called “geocoding”.

Creating geocoding software is almost never a simple process. The more variables involved in the software, the more complex the geocoding process becomes. One of these variables is time and the change of place names over time. In our spare time we have been developing an application called a Historic Geocoder, through which we aim to address the difficulties of geocoding historic pieces of information with a ‘current’ set of location data.

A good example of an Azavea application that uses geocoding is PhillyHistory.org, a publicly accessible site run by the City of Philadelphia Department of Records and City Archives. The site is a searchable collection of some of the approximately 2 million historic photos stored in the City Archives. A unique feature of the site is that a visitor can search by a current address and find pictures near that address.

Over the years the City photographers have documented the location of each photograph by using addresses. However, the catch is that sometimes street names change. When this happens, a historic photograph with a location description that has since changed is geocoded to the wrong coordinate location or cannot be geocoded at all.

Our Historic Geocoder research project consists of three parts: a) a record of street name changes; b) a database of street segment changes; and c) software to enable time-based geocoding.

By recording not only where current streets are and what they are named, but also where streets were in the past and what they used to be called, the Historic Geocoder will provide us with the ability to geocode based on both space and time. Instead of only entering a location, a user will be able to enter a location and a date and the system then locates where the historic address was during that time period on a current map.

Historic photos are not the only records with potential historic address problems. Surveys, censuses, and legal records all use addresses to describe locations. Being able to geocode these locations with relation to time is a very important first step towards the analysis of these data. Through our R&D work on a Historic Geocoder, we hope to make it possible to more accurately assign locations for historic data.

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Department of Records ParcelExplorer

By Michael McLarnon Published in

Vol. 2 Issue 1, January 2007

"ParcelExplorer enables public end-users to enter an address or registry map number and view property records...of the paper-based registry maps."

The Philadelphia ParcelExplorer application, as a project for the Department of Records, is one of Azavea’s latest web-based applications. Unique in the U.S. and already more than 100-subscribers strong, ParcelExplorer enables public end-users to enter an address or registry map number and view property records information including scanned version of the paper-based registry maps.

Additionally, users are able to measure parcels and lines; add annotation to the maps; display a printable copy; display condominium information; and display parcel history.

Registry maps, or land parcel record maps, have been kept in Philadelphia for a long time, but have only been recently digitized by the City’s Records Department. Digitizing the data means that they are much easier to organize and keep updated, but there was a desire to keep scans of the original maps, which were recorded on linen, so that they could be viewable along with the digitized data. The ParcelExplorer application solved this problem by enabling users to use scans of the originals as background to the digitized map (learn more).

There are several new features to be rolled out soon, most notably the addition of historic maps from the Philadelphia Free Library. These include the Hexamer-Locher Philadelphia maps made between 1858 and 1860, and land-use maps from 1942 and 1962. The historic map scans were made and contributed by the Athenaeum of Philadelphia. Another recent improvement is the addition of links to historic photos at PhillyHistory.org. Now, when you look at a parcel or historic map, you can find historic photos nearby.