Abstract

The Stolpersteine project is the world's largest decentralized memorial in commemoration of the victims of the Holocaust. It was founded by the German artist Gunter Demnig and up to this day over 75,000 stones were placed in over 1600 cities in 26 different countries. A Stolperstein is a small cobble-stone like object that is integrated into the pavement. On each stone the name of a Holocaust victim is written together with varying short information snippets. The stones are placed at the last place a victim freely chose to live. The Stolpersteine AR project is a prototype of an augmented reality mobile application that aims at detecting these stones in the pavement and displaying additional information in 3D about the person the stone is dedicated to. The basic idea of the application is that by visualizing the life of the victims and providing additional information the original intention of commemoration is enhanced. However due to the huge amount of stones and different locations an easy system to upload information for new stones and to maintain the information about existing stones is needed. A key concern for such a system is ease of use since people with the necessary knowledge about the commemorated victims typically don't have a computer science background. Therefore the initial approach of a web-interface is revisited and improved by the implementation of a new separate web-application. A short evaluation on the acceptance of the new web-interface and some smaller additions to the AR application that were implemented has been conducted in the form of expert surveys. The qualitative feedback from this survey is evaluated and taken into account for the outlook of future work for the Stolpersteine AR project.

Implementation

In the scope of this thesis the web-interface for the Stolpersteine AR project was reworked and set up as a standalone web-application. The original software architecture was expanded to integrate this new web-application which has been called Stolpersteine Manager. The Stolpersteine AR application retrieves data from a backend application where the data is grouped into locations, each identified by a set of geographical coordinates. Every so called Stolpersteine location consists of one or mulitple Stolpersteine which correspond to the real world commemorative plaques. Each Stolperstein has various pieces of information associated with them in the form of textual information and multimedia content, specifically an optional image and audio file. Therefore the web-interface offers a feature to create new Stolpersteine locations and add Stolpersteine to it.

Architecture Overview of the Stolpersteine AR Project

Architecture Overview

Stolpersteine Manager Web-interface

The web-interface was developed using the Angular framework. At the moment of writing, the site is hosted using Google's Firebase service: https://stolperstein-manager.web.app/ Please be aware that the site probably will be hosted elsewhere in the future and this link might not be active anymore.

Main view of the web-application which shows a street map. All Stolpersteine locations are marked on the map and can be edited when clicked on them. In this picture also the dialog is shown to create a new Stolpersteine location. The geographical coordinates can be filled in with a simple click on the map.

If a location is selected for editing this overview screen is shown. From here the location can be deleted or new Stolpersteine can be added. The existing Stolpersteine which belong to the selected location can be seen here and also edited or deleted. Additionally the Stolpersteine can be sorted via "drag and drop" which is important since the Stolpersteine should be ordered from top left to bottom right according to the real world installation so that the AR application can display the correct content to each stone.

When editing or creating a new Stolperstein this Stolperstein form is shown. The form is grouped into five categories: "Basic Information", "Media files", "Additional Information", "Relations" and "Life Stations". These categories roughly correspond to a specific sub-scene in the AR application.

AR App Modifications

For a detailed description of the augmented reality app, please follow this article:

[21SS - BA] Development of an Augmented Reality App for Stolperstein Memorials

For additions made to the augmented reality app in this thesis, continue reading.

A number of smaller additions have been made to the augmented reality application. Noteworthy are the possibility to display a custom amount of text boxes and an audio player which is used to play back an optional audio file.

Selection scene for custom text boxes

Audio player feature

Evaluation

The web-interface as well as the AR application was evaluated in cooperation with the LMU seminar Geschichtsvermittlung digital: neue Zugänge zu historischen Orten. Two students anserwed a standard system usability score (SUS) test on the usability of the web-interface and could also optionally give feedback on their experience with the AR application. The number of testers was very small because for using the web-interface and filling out the necessary information, expert knowledge is required to find out the relevant information about the Holocaust victims commemorated by the Stolpersteine.

SUS Test

The two testers rated the usability good to excellent with individual scores of 75 and 95.

Qualitative Feedback

The qualitative feedback section was grouped into feedback regarding the web-interface and feedback regarding the AR application. Only one of the two testers was able to install the test version of the augmented reality application and give feedback on this particular questionnaire.

Web-interface

The overall reception of the web-application was that it is easy to handle and clear which means that very functionality was easy to find and use. Also the data fields in the Stolpersteine form were thought to be self-explanatory. Additionally suggestions were made by the testers on how to improve the application.

• A search functionality in different places of the application would be useful. Not only to find specific existing content but also to fill out geographical information e.g. when entering a city for a life station.
• Content should be made sortable when multiple items can be added in a category. This helps users to structure the information and on the occasion of text boxes could also be useful to display them in a specific order in the AR application.
• The text box feature was received very well and it was suggested to improve it by adding customization options for the text boxes and allowing the upload of images which are displayed above or beneath a text box.
• Relations between a person with Stolperstein and person without a Stolperstein should be possible (currently both persons need to have a Stolperstein)

AR application

The feedback on the AR application can be broken down into two categories. The first one is improvements to the interface and graphical improvements and the second one is improvement of content and adding or improving features. Also the reception on the AR app was very positive and the app was thought to be useful for education purpose in schools or for tourists.

Graphical improvements:

• Use symbols to depict the context of e.g. life stations on a map. For example wedding rings could be used for a marriage life station.
• Make the interface more appealing and possibly rework it

Content and Feature improvements:

• Text box improvements (see section on web-interface feedback)
• Access external links inside the application to get additional information on a specific topic or to link to an external source. Possibly also multimedia content could be integrated in that way.
• Relations to people without a Stolperstein (see section on web-interface feedback)

Conclusion

In the scope of this thesis, the development of a mobile augmented reality application for the Stolpersteine memorial was continued. The main focus of this work lies on the improvement of the web-interface used for entering data for this application. Therefore a new web-application called Stolpersteine Manager has been created which is based on the Angular framework. This new interface fixes the issues with the original web-interface and implements previously missing functionality. Additionally new features for the AR application have been added which are also reflected by the new web-interface. To be able to test the applications the web-interface and backend application have been hosted publicly for the first time.

A qualitative, formal evaluation was conducted on the usability of the Stolpersteine Manager and the general reception of the augmented reality mobile application. This evaluation was performed as an expert survey since supplying data for the Stolpersteine application requires historical knowledge and research skills to acquire the necessary information. The survey itself consisted of a system usability scale test and a number of questions targeting the general user experience with web-interface and mobile application, also with the intention of collecting suggestions for future development steps.

The evaluation proves that the augmented reality application as well as the new web-interface are perceived as positive and development should continue on the foundation of the currently existing software. The test users confirmed that they think the application helps people to get in touch with local history and the important topic of the Holocaust. It has been pointed out that especially the younger generation, also in the form of school pupils can profit from this application by providing a more vivid experience than the Stolpersteine on their own. This coincides with informal evaluations performed with the initial AR application protoype. The web-interface has been described as clear and easy to handle. It is important to note that the test users had no computer science background in order to perform an evaluation that is as close to the planned regular operation of the application as possible.

The Stolpersteine Manager has proven to be a valuable tool which should be developed alongside the AR application. We also believe that such a web-interface can lay the foundation for similar cultural heritage based projects. The augmented reality application is still in a prototype state and suggestions have been collected on how web-interface and mobile application can be further enhanced. This thesis therefore provides valuable information for the continuation of this work. However not all topics which are important for a future development are covered by this thesis and need to be considered for future work which namely is the performance of the AR application.

Resources

Demo Video

Stolperstein_Hiermeier_Demo.mp4

Complete Thesis (pdf)

Final Presentation Slides

Installation Guide for all Applications