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CartoDB / camshaft

Analysis library to create data views from queries
BSD 3-Clause "New" or "Revised" License
17 stars 7 forks source link

Be careful when computing time/distance ranges for isolines #158

Open iriberri opened 8 years ago

iriberri commented 8 years ago

Here we're building the range from the maximum range value set up by the user and the selected states.

At this issue we noticed that one of our isoline providers is not returning information for small ranges, such as 10 or 34 meters. This is not an explicit limit in their API so basically depending on the point you would have a minimum bound or another. I opened a question in Stack Overflow to see if someone knows something about these limits, but I don't expect much from it: http://stackoverflow.com/questions/38523173/is-there-a-minimum-range-limit-for-here-isolines

I'm opening the issue just for the record, because we might want to avoid really small ranges as, even though the result will be an empty isoline, that would waste quota.

AbelVM commented 8 years ago

It looks that there's no node and/or way of the topology network that falls within the required distance. So maybe your point is disconnected from the network, separated by that amount of meters.

V.g.: a mall that has a parking lot, a place surrounded by pedestrian streets, etc.