## 4 Conclusions  
The staggering mega-urban environments of the poorest of the poor have been used as a worst-case laboratory to test state-of-the-art smartphones and their geo-related applications on-site for their capability of delivering adequate geo-data and providing socially and design relevant services. Working in the field of informal urban settlements and slum upgrading projects offers a multitude of opportunities for landscape architects to go back to some essential contents of the profession [3,4]. In a universe next door, there is an overwhelming and fascinating potential of information gathering and design work, which is as yet nearly untouched by landscape architecture. While the comfortable, affluent side of the urbanized planet seems to be buried under all thinkable sorts of information and  
Figure 16: Photomontage with superimposed 3D plant models and climbing aids. Figure 17: “Foreshadowed” inchoate, georeferenced design visualization (GK _Baseco_) on the digital globe _Biosphere3D_. information overload, the other, uncomfortable side of the coin seems to remain a blind spot in the global consciousness. Conducting this research parallel to the guidance of design studios with a social background has been an actual challenge. Therefore, we regard this article as a reflection on methods, experiences, problems, necessities and ideas. After the two research trips to Manila, the chosen approach of Grassroots GIS with simple fieldwork tools based on common technology can be found adequate. We have learned four essential lessons; (i) Low-cost mapping tools and free and open platforms such as OpenStreetMap are essential to operate in urban informal settlements, _i.e._, to become independent from non-existent maps. There are many urban sites that have not yet been sufficiently mapped or mapped at all, where, e.g., aerial photos and street maps on Bing Maps or Google Maps are not up to date or too coarse-grain; (ii) Simple fieldwork tools and methods have proven to be efficient and practicable in terms of mapping speed and data quality on both street map(ping) scale and for photographical documentation; (iii) Precision has it is price. There are tasks such as accurate leveling or measurements with accuracy superior to standard GPS that simply cannot yet be achieved with smartphones and Apps; (iv) OpenStreetMap and standard GPS reach their limits on a street map scale. An adequate scale for outdoor design, especially in narrow and fragmented urban informal settlements would require a mapping and dissemination platform on cadastre level, e.g., up to 1:500. Grassroots GIS is an effort towards geo-referenced landscape _design for the real world_[11], e.g., making use of Web 2.0 technology, which seems definitely callow enough to be pursued. Compared to the efforts and outcome of _Map Kibera_ and for the short term, measurable results such as our own map uploads and edits to OSM are certainly marginal. Anecdotal evidence of _Baseco_ suggests that blank spots on the (e.g., OSM or Google) map disappear when volunteer geographers pioneer on these sites. The mediated collaboration between volunteer geographers and a slum-upgrading project has been recognized as a win-win situation and should definitely be adopted by more projects. Apparently, the success of GK projects greatly relies on their trial and error approach and their ability to learn from best practice examples adapting these to local conditions and needs. To \"spread the word\", we seek to publish findings of Grassroots GIS as a kind of hands-on tutorials in a GK Field Manual [5]. Then, a substantial evaluation of our Grassroots GIS approach, e.g., to assess which methods were successfully adopted by other slum-upgrading projects, would be expedient. This could involve comparison of mapping and editing activities on OSM for GK sites. For the time being, the authors plan to refine the Grassroots GIS approach in further case studies to develop a more robust, rigorous methodology.