Mapmakers and testing

I like maps. Last night I attended another event in a series of events known as the Festival of Maps here in Chicago. Dennis McClendon, a cartographer hosted a talk on field testing street maps.

In mapmaking, field testing means getting out and verifying maps against reality. Accuracy is essential. Dennis walks, bikes, and drives to check for accuracy. He’s measured buildings in downtown Chicago to get accurate readings. And he’s forged through some tough terrains to get information from back roads, waterways, railroads, and farm lands.

He mentioned having had clients that want to skip the expense of field testing since they don’t understand its value. I couldn’t help but tune into this comment as I know lots of companies that skip testing. Dennis talked about the gaps he finds – gaps in what would seem to be valid data when he compares satellite drawings, town maps, and developer plot plans versus what he finds in the field; reality doesn’t always align with documentation.

Dennis had some humorous slides showing discrepancies between what a map shows and what reality offers. One was a slide of a street that’s been blocked off with barricades, another showed a well-established house and garage where the map shows the street as going straight through. Satellites can’t see everything and mapmakers look for discrepancies. By now this was all sounding familiar to software testing.

He also mentioned how asking questions and taking notes help him with his work. Both are practical aspects of being a mapmaker. As a mapmaker, Dennis has learned to ask questions of realtors, town officials and builders. He looks for clues to streets he might not have known about when he hears about restaurants and stores being built. I have to wonder what it might be like to be in a car driving about with a mapmaker – perhaps it would be like watching a tester navigate around a website musing and note taking all the while. Dennis showed sample notes from his field work. I asked about his note taking and if he feels his notes have evolved over the years. He didn’t think they’d changed much but he did say he has his own shortcuts in note taking.

And he talked about things he’s learned over time. How developer’s drawings may speculate streets that never come to be, referring to these streets as ghost streets or paper streets. And at the other end of the spectrum, streets that people carve out physically with their vehicles that become streets in remote areas of Utah and New Mexico. Mapmakers find gaps. What shouldn’t be – may be and what should be – might not be.

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