I had this idea about making captchas, this annoying images of unreadable text, a little more intuitive and useful.
The approach is similar to reCAPTCHA, though I would find it less annoying:
Why not have people solve simple recognition tasks on aerial imagery?
The captcha would contain a small aerial image and the user would have to solve a simple task like “draw a circle around a lake” or “click on 5 houses on the image”.
The results would be compared with results of other people and already existing data, so the captcha would be very hard to solve for a bot (as it would be very hard for a bot to draw maps, that’s why we do it) and at the same time we would get approximately good results.
Technical Background
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i thought of HTML5-canvas as the basis for the client side. there you could draw points, lines, polygons and free hand paths. And by now it’s supported by any modern browser (even good old IE)
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the server would load a random piece of aerial imagery (well, not entirely random, more on that later)
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the client would solve the task and send back the coordinates of his input
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the server does a plausibility-check and lets the user pass (or not)
Tasks
There would be different tasks for different qualities of data in the source:
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Level 0: Recognition
Used on regions with very few or no mapping data exists at all. The problem is that we have no way of making plausibility-checks for the first few people that click on unknown terretory, but if we have 100 people at a time trying the same image it’s an easy task to compare results. Possible questions:
[list=*] -
Draw a line along any road you see
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Click on the roof of a building
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Draw a circle around a forest / lake / village, etc.
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At which of the marked location stands no house?
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Which of the marked areas is not inside a forest?
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Click on any line that is not near a road
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Draw a path around the house marked on the map
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Draw the shore of the lake in the highlighted region
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Retrace the road in the highlighted region
Validation
Can we already import the data into OSM? Well, that depends on the quality of the data and that’s a thing that I don’t want to leave only to the captcha-solvers, so here’s my idea on that:
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The results are uploaded on a dedicated server, where real mappers can look through all the captcha-results
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To make this efficient, the captchas are placed in a matter so that they are not spread randomly over the world, but concentrate on a few regions (which could be decided by the mappers that care for the system, for example)
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When a new resultset comes in, the mapper can look over it, make some final changes, put it in context (e.g. creating the connection to a road of the neighbor region) and then mark it as reviewed.
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The reviewed contents can be uploaded to OSM directly, or you could introduce a policy to doulbe-check, or you could make a mini-game out of it where users get points for regions they review… anything that motivates
The alternative to captcha solving would be to make a minigame out of this, as proposed in this post, but i kind of like the idea to make the crowd also work for OSM instead of just Google books.
I’m a programmer and I’m currently searching an interesting topic for my bachelor thesis, so this might be just what I’ve been looking for (though I’m a little worried I might fail on it because it’s too complex)
What do you think about it?