There isn't one map of the world. Anyone who has worked with maps for a while knows this -- that the process of making a map is something that is creative in form, and that all of the pieces that go into it play a major role in what comes out.
However, I keep hearing people talk about OAM having a single map of the world, so I think that it's important to realize why this doesn't work. - Almost every important use of OpenAerialMap involves some need for editorial control over what the resulting product from the map is. Humanitarian aid, for example, typically centers on disaster hit areas -- and in almost all cases, the most important thing for imagery is recency. Seeing imagery from before and earthquake, even at 5 times the resolution, doesn't solve the problems for disaster relief. On the other hand, an organization wanting to put an overview of an area on their website -- say, for example, the 2012 Olympics wanting to put together a high res flyover of their area -- are not going to want to have a blurry kite flown image uploaded over the top of their data and obliterating it. With every use case I can imagine for OAM, what is the 'best' image of an area for one user won't be the best for another. With that in mind, we should realize that attempting to present one map of the world which can meet the needs of users of OAM data is very unlikely. - Every piece of imagery tells a different story. OSM has the idea of "ground truth wins" -- that is, local signage verified by locals wins over anything else. With data, that's a reasonable approach. However, aerial imagery is not data; like the maps themselves, each aerial image is a creative work, prepared via a certain process and attempting to achieve certain goals. One story I heard at FOSS4G was from someone working in Nome, Alaska. In 2010, Google had a great image of Nome -- cloud free, high resolution and crisp. In late 2010, it was temporarily replaced by a more recent image -- entirely of clouds. For other purposes, people will want winter imagery, summer imagery, leaf on, leaf off, high resolution with high contrast, mid-sized resolution with medium contrast, etc. Every image that goes into OAM tells a different story. Imagining that any one person can put these images together into a cohesive whole is ignoring the multivaried uses that OAM can have. In addition to the more philisophical reasons that this is impractical, we shouldn't ignore the technical limitations that have led to the current design as a catalog: - Many of the uses of OAM data concentrate on small areas -- disaster recovery, environmental impact monitoring, property assessment. Recently, a local team flew balloon imagery of a landfill/incinerator site: http://mapmill.org/images/2011-10-10-saugus-landfill-a This type of data is highly localized, and the needed output is also highly localized. Investing massive resources into hosting a worldwide tileset means that we have to dedicate fewer resources to meeting the needs of highly localized datasets; even though the map of the Saugus landfill will have almost no impact for the average user, for the people working on the project, it is far more important than presenting an accurate landsat image of Madagascar. Given the enormous challenges present in presenting a view of the world, and given the high likelihood of benefit being seen at a local level first, I would highly recommend that people start by thinking of OAM as "an Open View of the World Around You"; rather than trying to imagine solving the much more difficult problems of worldwide imagery, start by helping people build maps of their towns, or their houses. - Maintaining a cohesive worldwide cache designed to act as an aerial/satellite map is a full time project. (When I say 'full time', I mean it -- I think that you would need at least one person working full time on it just to keep it functioning as intended, given the massive amounts of data that go into it and the potential risks that come out of it.) While I understand the base desire -- 'stop depending on non-open data' -- I think that given the limited developer resources available to OAM, and the technical limitations that such a project would have, it really is best for the community to try to focus first on meeting the needs of small scale projects. At one point Schuyler and I had hoped that we would be able to solve this problem trivially using remote data to create maps of the world, but having explored these options to some extent, I become more convinced every time I try that this is definitely a huge job -- one that can be built on top of OAM, but should not *become* OAM. OAM should concentrate on cataloging and making imagery discoverable for all users, rather than creating a single map of the world to help only some. To that end, I would like to make it very clear: At this point in time, I feel that OAM is not in a position where building a worldwide cache designed to replace commercially available tilesets for base ortho imagery is going to be the most likely thing to help the needs that OAM can help to solve the most. When the next earthquake, flood, or tsunami hits, I feel that it would be best for everyone who is participating in this community to be able to really have tools built around "The World Around you" -- and if we succeed massively in that regard, I think that it would be easy to imagine scaling up. There are too many different views of the world to make them all work equally well. Let's get it so that people can build *their* view of the world arond them first, and then move on, rather than trying to come at it the other way: anything other than that seems likely to leave us all stuck in the mud, and no better off than we have been for the past 4 years. To that end, I am actively putting my money where my mouth is: my hope is to spend the next couple weeks building a service which allows users to build a local view of the world around them, combining the imagery available in OAM in the way that they see fit. (This work has been started in https://github.com/crschmidt/mosaic-webui ; it's far from done, but progress is happening.) I'm also exploring the use of MapMill[1] and MapKnitter[2], two great tools for helping build better maps using highly local imagery. Anyone interested in helping on OAM, I highly recommend you get engaged by exploring the data and the world around you -- I think that it's the best possible way to get a better understanding of what is available -- and how it can help. [1] http://mapmill.org [2] http://mapknitter.org/ Best Regards, -- Christopher Schmidt Web Developer _______________________________________________ talk mailing list [email protected] http://host134.hostmonster.com/mailman/listinfo/talk_openaerialmap.org
