One of the airfields I flew from was a base for the OS photo surveying unit. They had a 'plane which had been modified to have a downward pointing, very expensive camera built into the fuselage. They could then fly long straight strips, taking overlapping photos and then taking overlapping strips. The pilots didn't stay long - it was a very difficult and tedious job getting the strips to line up. They flew a few in a day, always in the same direction to assist with the way your track gets moved by the wind.
Cheers, Chris John Robert Peterson wrote: > Part of the idea of this project was to kick start thinking about this > sort of thing. > > The ideal situation for me would be if we could have some automated > tool on a sever somewhere receiving images from users, and > automatically rectifying them. > > This sounds imposable, but I believe that with a very small amount of > user help it could work: > Images can be automatically pinned together in overlaps (and high res > images can be pinned onto wide area images) using tools similar to > those in Panorama Tools / hugin (this searches for notable points in > the image data, and matches them between images); > searching the images for road markings (and/or cars) and matching > these to the gps traces already uploaded would give a reliable enough > way to add real world control points; > if a concept of altitude is added, automatic control points between > images appearing on top of skyscrapers would not be too damaging; > approximate terrain relief for most of the planet is already known, > this can be tied into the above to help; > manually adding control points would be done by displaying already > rectified images next to a map, with the user adding pins to useful > points; > images with no rectification data at all would be added using a push > pin system similar to that used on http://warper.geothings.net/ > > the above is a pipe dream at the moment, but has the potential to > revolutionise how we do things in my opinion. > > Any further ideas on this? > > The images of stratford were taken mostly angled, with a few almost > vertical. we spiraled around the town and I took images out the > downward facing window, it seemed to work pretty well (if the results > are a little chaotic) > > mapping from these images is the million dollar question -- the raw > images are going up online at > http://www.flickr.com/photos/thingomy/collections/72157622345143470/ > and are fine for visual reference while mapping, but rectifying them > is a more tricky issue. > > JR > > > 2009/9/14 Tristan Thomas <tristan.tho...@wikinewsie.org > <mailto:tristan.tho...@wikinewsie.org>> > > > Many of the photos taken above Stratford upon Avon seem to be > taken at an angle-how do people find them for mapping from? > > > 2009/9/14 Chris Hill <o...@raggedred.net <mailto:o...@raggedred.net>> > > I used to hold a pilot's licence and I did some work > photographing archaeological sites. Photos taken pointing > sideways are much harder to work with than photos pointing > straight down. Any kind of rectification adds unwanted > artifacts. I used to make high bank angle turns (60' bank > angle) over the feature I wanted to photograph which made it > very easy to photograph. > > I was trying to photograph a small area in detail, so circling > over the feature helped. I was also using film (before > widespread hi-res digital), so there was a limited stock of > film but the resulting image was the equivalent of about 25mp. > To reduce parallax I used a telephoto lens. > > It gives a very interesting overview, but it's not a patch on > surveying on the ground where you have access. > > Cheers, Chris > > Tristan Thomas wrote: > > I would be very interested to hear what people think of > this effort. I'm currently studying to be a pilot & I > know that many people who do fly routinely take aerial > pictures of the landscape below, especially of towns etc. > I know most of them would be more than happy to allow > their photos to be used of OSM. If we could find a way to > upload them somewhere, then I'm sure we could dramatically > increase the aerial photography we have without having to > pay to hire the planes or get it sponsored. I could just > upload them all under one Flickr account for OSMers to > look through & do some tracing if they wish, but it > doesn't seem the most efficient way to do it? > Thoughts? > > ------------------------------------------------------------------------ > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org <mailto:Talk-GB@openstreetmap.org> > http://lists.openstreetmap.org/listinfo/talk-gb > > > > > > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org <mailto:Talk-GB@openstreetmap.org> > http://lists.openstreetmap.org/listinfo/talk-gb > > > ------------------------------------------------------------------------ > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-gb > _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
