Hello everyone, Have been thinking a bit more about my own interests within the "OpenStreetView" project introduced by John McKerrell at SOTM. My particular interest is an in the field navigation tools for countryside users, particularly walkers/hikers/mountaineers etc, which I'm giving the codename "footnav" for the moment (seeing as John already has openstreetview and I'm more focusing on the countryside!)
One option is simply to have a computer generated 3D view from SRTM, OSM and 3D models of stiles, gates and so on. However I'm quite interested in using actual photos: the advent of "compass phones" such as the N97 and latest iPhone makes this a realistic possibility. What I'd like to do is build up a database of photos taken along a path or footway, say every 10 metres or so. If a user wanted to navigate, the app could locate the nearest photo to them, based on location and direction of travel, and display it, with their position and OSM data overlaid on the photo. I was on top of a hill looking down at a valley the other day and was thinking "how cool would it be if I could see a photo of that valley and have all the footpaths overlaid on it"! I've done a bit of OpenGL and believe something like this could be done if the position, direction, slope, aspect ratio and field-of-view angle of each photo were known. Most of these I have ideas on how to obtain, or at least where to go to look it up, *except* the field of view angle. The thing I don't really know much about is: how can you get the field-of-view angle of a photo taken from a digital camera (either a standalone camera or within a phone)? I've seen a few explanations on the web on how you get it from the focal length (which appears to be quoted in e.g. the N95 specs) but they also require another parameter (the "size of the film"). Where might I get this from? If anyone's an expert on photography theory I'd welcome any explanations on how to obtain the field-of-view angle of digital photos. Thanks, Nick _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
