Concluded #GrabOSM mapathon

Hi Everyone,

We’ve concluded the #GrabOSM mapathon, I’m looking through the changeset right now and where many entries are of high quality, some of them are lacking. I’m going through the data contributed with this hashtag now and will be reverting / editing them quickly over the weekend before anyone builds any data on top of it.

If anyone else would like to comment on the work or would like to revert the changes, please feel free to do so. I’ve already informed the participants that if they find their entries have disappeared, this is why.

Best Regards

Hello Mishari,

thanks for following this up and cross-checking the edits.

Sad news is, that edits made it into the live data whose quality is so low that it needs to be reverted.

How could the training improved so that this would not happen in the first place? It’s creating extra work for others like you to later clean up. And probably also frustrating for those who added it in the first place.

So how to educate new mappers properly in such events so that additions are meeting some acceptable quality level in the first place.?


Hi Stephan,

I think a few of those were carelessness and confusion that happens when facing a new interface. For example, somebody dragged a whole segment of road that was attached to a node across.

There were others which were due to a lack of understanding about the entire process, cluster of buildings being marked as building=yes or name=my friend’s home

Next time I’ll pass out worksheets that will require participants to specify what they will be mapping and then bring it back to me to check before going on to map the next thing. I think keeping it deliberate this way and forcing immediate feedback after a changeset will improve quality levels.

Here’s a summary of what we did:

We had a total of 47 RSVPs and 70 people showed up. Many of the participants were family with kids which I think is special as kids who are interested in Geo have the potential to be future leaders in the field. If the family decides that they enjoy mapping together it has the benefit of tightening social bonds as well. We saw many examples of collaborations between parents and their kids at the event and also had participants from the Thai GIS community and Universities.

According to OSM Changeset Analyzer on the tag #GrabOSM we had a total of 166 change sets. After a review 135 changesets were considered high quality. Of the 31 remaining I had given feedback, reverted or fixed all of them and only three of the changes were alarming (re-tagging a school in China and an entire segment of road being tagged as a pedestrian crossing and some roads being dragged in the North East). Most issues were sub-optimal drawing and tagging. Today, at least two of the participants are still actively mapping. The very good news is that we avoided the quality issues that plague HOTOsm mapathons and I will be designing more mini workshops to ensure that the remaining source of errors are further reduced.

According to the changeset statistics we created a total of 1368 nodes, 324 ways, 249 buildings with participants mapping in Bangkok, Sakolnakorn and Songkhla and helping out with the HOTOSM efforts in Sri Lanka and Tanzania. Several of these were details of private facilities such as MT Arena and St. Dominic School.

The Mapillary activity also wasn’t bad, with a handful of photos being of the floor, the main challenge is the GPS quality in cheap smart phones, but I feel it’s the responsibility of Mapillary to deal with that challenge and that some data is better than nothing. You can see the results here, the tracks heading north and south (up and down) were generated from the event and has already produced meaningful data

Best Regards

Thanks Mishari, that’s good news.
I wished there were some more people in south east asia who could provide the Grab mappers some initial guiding - there were complaints on grab mappers’ quality in Indonesia ( ), and in Malaysia the quality seems also poor ( )…
So it is really great that you help the Thai grab mappers with getting started and finding the correct way.