4.24.2012

Free and Open Data Reliability : The case of Open Street Map road data vs "PAID" data sets

This is the very typical example why the people in our country should free our data!


Shown above is a map of my road data for a hydrologic model. Two unaligned road networks are visible from the image above. The red lines are my initial datasets which are actually "PAID" dataset from a government agency. When I did an overlay with a pan-sharpened satellite image, I got a large shift from the actual road network visible in the image itself. My initial notion is to georeference the image so that it would fit the readily available road data. However, when I tried overlaying the location of my mapped inlets, I noticed that the storm drain network which is aligned with the road coincides with that of my backdrop image. These inlet locations are in-situ observations gathered from a week of fieldwork hence there must've been a BIG problem with my road dataset. My next solution is to look for a free dataset. I have tried using Open Street Map data and alas! OSM data has a better fit! The yellow road network above which tends to coincide with the blue network of dots is actually the road data from Open Street Map. See how great and more reliable those FREE and OPEN datasets are?

Of course there may be some risks in using these free datasets but for my purpose, the OSM data obviously provides a better accuracy as compared to the "PAID" datasets that we get which are highly erroneous and on the first place.. shouldn't be PRICED at all!

I think our government should somehow consider this example. There's no harm really in opening our data to the public, the limitations should by far be set properly though.

With free and open data we get a WIDER COMMUNITY to do the refining for us. The blunders are fixed through time and we get something that's FREE and USEFUL and MORE RELIABLE for our ancillary datasets that would soon build a a more seamless layer overlay and analysis in our own geographic information system.

1 comment:

  1. Good to know that OSM data is comparable (and even better) to "PAID". I hope you can contribute to OSM as well in your spare time. BTW, I think that area is somewhere in Marikina. I did most of the OSM data around that area using my bike. :)

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