[Editor's note: When data lacks precision, don't zoom in past it's accuracy, yo. In Washington, DC, we often receive crime statistics located at the block level. A single point could represent any of a couple dozen to hundreds of housing units on a certain street block. The symbol either needs to show the fuzziness, or the map should not zoom in to a level where a symbol becomes associated with a specific property unless it is spot on. Datum issues, where a hundred feed offset can put the dot, even when using high precision, on the wrong side of the street further complicate the issue.]
Republished from PerryGeo.
Another disastrous consequence of inaccurate spatial information… Not only can you accidentally tag your neighbor as a criminal, now it appears that sloppy spatial data has lead to the wrong house getting demolished.
I’ve asked it before but its worth repeating … with all the recent advances in spatial data publishing, where are the advances in metadata and data quality assurance? How do you know where the data comes from, what’s been done to it and by whom? What is the intended use of the data? For the vast majority of the data being shoved out onto the web, these bits of metadata are sorely lacking.
Of course this case is more a matter of one person’s sheer stupidity; I’m not sure any caveats in the metadata would have stopped the wrecking ball!
Tags: accuracy, crime, dc, demolition, gps, Mashup, metadata, perrygeo, precision, quality control, scale, stupidity, zoom level
I think this is not “caveats in the meta-data” but something we need to work out in UI presentation. machine-era outputs are generally pretty good at expressing limits-of-precision. Digital-era outputs seem designed to kill people.
One of my favorite examples is the temp readout during the TMI-2 accident. The digital readout says 280°. Hot, but not dangerous yet. But that’s the readout, which someone decided could work like a dial and just stop at off-scale-high. Without the dial telling you this, no one knew that it was not 280° but “off scale high” and therefore unknown-bad. Just make the digital readout like the mechanical dial and everyone is much more informed.
I ranted about it a tad more at the blog I never update anymore here: http://shoobe01.blogspot.com/2007/06/off-scale-high.html
There are, similarly, good ways to express position on a moving map display (though often ignored) but even then position is always numerically expressed to the meter or better. Which is wrong.