Georeferencing Historical Maps: Applying Map Warper to Ottoman Urban History

Digital research methods and software that allow spatial analysis enable different research questions to be produced by moving cities, places, or buildings to the digital world. Spatial analysis of historical sources through Geographical Information Systems (GIS) is becoming vital to observe changes and transformations through time. GIS offers urban historians the opportunity to reconstruct spaces in different historical periods in a digital environment. There are several pieces of GIS software such as ArcGIS, QGIS, MapInfo, AtlasGIS, GRASS, ERDAS, GeoMedia, and TNTlite. However, using these pieces of software often requires an advanced level of computer knowledge that can hamper historians. Additionally, using these programs in history classes can create technical and financial difficulties. For example, whilst some of these pieces of software are open access many are not. Moreover, scholars may not have enough experience to teach such advanced level programs practically and students unfamiliar with new research methods may lack the motivation to try using them. In this article, I will introduce Map Warper, an online map georectification application that is suitable for teamwork in history classes, and has a user-friendly interface for spatial analysis.

Developed by Tim Waters, Map Warper is very useful for matching historical maps with current coordinates through OpenStreetMap. Map Warper, which is free and requires only basic computer knowledge, is an easy-to-use initiative for studies in urban history and spatial analysis. By adding historical maps to the digital environment of the present time, users can observe changes and transformations during the periods in separate layers and on the same screen.

In 2020, I joined Dr. Yunus Uğur’s HIST 405 Historical Geography class to teach GIS. Since open source GIS software such as QGIS is difficult to use and make progress with in large student groups, the need to find different mapping programs led me to Map Warper. The studies we conducted with the students within the scope of this course show how Map Warper is compatible with applied urban history courses. Using Map Warper provided an entertaining way to both increase the awareness of history students about digital studies and to overcome prejudices about the complexity of computer-aided research methods. During the course, we had the opportunity to analyze and observe historical changes and transformations by matching historical maps of Istanbul from the 16^th– and 19^th– centuries with current coordinates. By comparing these historical maps and the current situation of the city, the students were able to discuss temporal urban changes and the construction and demolition of structures in Istanbul. Another nice feature of Map Warper is that every project is recorded on the website as data that can be used by other researchers. Thus, in this course, many historical maps of Istanbul were transferred digitally for the first time as raster layers and data were produced as a source for all Ottoman historians. Here is one example of the data students have produced.

You may be asking, how can I use Map Warper? So, let’s take a closer look at this great initiative!

First of all, you have to create a user account on Map Warper’s website by clicking on the Create Account tab.

 

Then you can upload the historical map to Map Warper via the Upload Map button. After filling in the information boxes such as name/title, select your historical map from your computer with the Select File button on the left side of the page and complete the uploading process with the Create button. (Depending on your file size, upload speeds can be slow).

 

 

After uploading your historical map to Map Warper, you can start georeferencing with the Rectify Map button.

 

 

With the Add Control Point tool, mark a common point on your historical map and the current map. To fix the points that you marked on the map, you need to click on the Add Control Point button at the bottom. To successfully reference the entire map you should add at least 50 points.

 

 

 

If you add a control point to the wrong place, do not panic! You can find it according to its number and delete it via the Control Panel.

 

 

Another attractive feature of Map Warper is that it allows you to download your work in different formats. Thus, you can create 3D views by moving your raster map to Google Earth.

 

 

 

The below video shows the 3D referenced Istanbul map of German Blues dated 1913-1914. This study was prepared using Map Warper and Google Earth programs for the Center for Urban Studies by Fatma Aladağ.

 

 

I would like to thank Dr. Yunus Uğur and all the students of HIST 405 class for creating an effective study environment!