Over the weekend we had a great time micro-mapping Hyde Park in Northbridge, and made some new friends! Some attendees of the recent Geogeeks/QGIS Users’ Group presentation evening joined our mapping adventures for the first time.

After getting everyone set up with a surveying app on their phone/tablet, and having our much needed coffee, we wandered around in rough groups adding whatever we could see. We ended up with a lot of double mapped features, because we weren’t very clear about who should map what to begin with. But this was not a big problem: the duplicates were easy to fix up after the fact in JOSM, and as a learning exercise, it was well worth letting everyone follow their interest and explore the world of OSM tagging.

That is the corner of the park that we most thoroughly mapped. Most of the POIs were added on the day, and the grass/garden areas were surveyed on paper and traced in after the fact.

This was a very successful way of surveying shapes under tree cover. The pages are screenshots of OSM data over imagery prepared in JOSM (with a “type:node untagged” filter active). After drawing on the pages (ahem, getting Dean to draw on the pages for me), I used Google Drive’s “scan document” feature to get a digital copy without any perspective distortion. (Writing this, I realise that there is a scanner in the house, which would have been easier!). I then used the PicLayer plugin for JOSM to align the images in the editor, just like satellite imagery.

Because there was such a big focus on learning OSM, only three of the pages were surveyed, but it is such a powerful technique, that I will be filling out the remaining sheets on subsequent visits.

We have now run three casual mapping parties in the “Social Mapping Sunday” series, and they are always a bit different but each one has been as fun as the last.

Shenton Park

In Shenton Park, lots of brand new mappers showed up and were introduced to OSM for the first time. About 13 of us in total! Meeting in the park and walking to nearby features to map worked well.

We didn’t come prepared with specific material to introduce new mappers, and we ended up spending a lot of time installing apps and setting up user accounts, etc. This was not a problem per-se, because it needs to be done. But it would have been smoother if we had a link to send people to which helped people get set up with the basics.

Mount Lawley

In Mount Lawley, 6 of us returning mappers set ourselves some explicit goals, and got a lot of data added to the map. We set the goal of mapping all of the shops and their names, footpaths, benches, bins, bus stops, bike parking and trees. We started in the middle of the shopping strip with a small team on each side of the road, and worked all the way to one end. Even though we didn’t map the whole retail strip, the are we did cover, we covered completely, which is very satisfying.

This gif shows the multiple stages of editing that these events encourage: The first step is cleaning up existing data and tracing features from imagery. This is important because it makes it easier to add data during the survey. It is also the best time to make assumptions based on the imagery, because any mistakes will be found during the survey. The next step is adding all of the data during the survey. The final step is cleaning things up, removing a few duplicates, fixing the odd tag, and generally making things neater with more powerful editing tools.

Organising

I have followed the same basic process that I described in my last post, for organising these events, but a few adjustments should be helpful. I have started a page on the wiki to document the process (in the hope that it continues to run, even when I can’t organise it).

It is important to do whole-group activities before everyone heads of to do mapping. That means before we start mapping we should: 1. take a photo of everyone, 2. decide on the details for the next event, and 3. decide on how to reconvene after mapping, for those who will stick around. Then 4. decide on mapping goals.

I have cobbled together a script for creating the before-and-after gifs showcased in this post. The most important part, is the awesome rendering engine Map Machine, which takes .osm files as input, so I can render the same area with the same settings passing in the data from different points in time (that I saved out of JOSM). I then use Image Magick’s convert to put the frames together into a gif.

A couple of weeks ago a small group of local Perth mappers came together in Claremont to meet with the local OSM community, learn a little more about contributing to OSM, and do some on the ground data gathering. Here, I will ~~ramble about~~ reflect on the experience and the planning of the event.

Although the turnout was small - just 6 of us - the event met its goal and I am considering it a success! I am Hoping that the humble little gathering will be the beginning of an ongoing community building activity.

Our morning

On a Sunday morning, we

1. met for coffee and introductions,
2. decided on a division of labour: each person chose a different feature to map,
3. wandered around mapping for 2 hours, then
4. met up again for lunch.

Meeting for food, both before and after, was good fun and made the event worth while, regardless of the OSM outcomes. I believe this is an important part of the formula; ensuring that everyone enjoys the time they’ve dedicated to mapping and wants to come back. Enjoying the time spent contributing to OSM is more important than the efficiency, and will result in more contributions in the long term.

Some extended time sitting comfortably in cafes was also a great space for sharing our OSM knowledge. Plenty of well motivated, specific question came up, and were met with immediately useful answers, without any prepared presentation or teaching material.

2 hours of on-the-ground-mapping seemed about right to me.

Our Tools

The main tools that we used were

• OSM Go! (android) for adding shops, trees and amenity POIs.
• Street Complete (android) for adding details to existing businesses, buildings, and amenities.
• Pen and Paper for recording footpaths, parking lots and parking access, and correcting geometry.
• JOSM for tracing buildings and paths from aerial imagery before hand (see below) and for adding the details recorded on paper after the event.

Dividing work by feature type was a good fit for this group size and location. I would like to experiment with encouraging even more specific goals before we begin - such as “add all shops (type and name) in this area” or “add all trees, benches, bins and bike parking along these streets, as far as I get” - as I have found these kinds of goals very useful in my own mapping.

I will be asking for more feedback from everyone at future events, about how well these tools worked on the day.

How it was organising

1. Chose an interesting location, making sure it had food options, good transport access, plenty of details to map, and appropriate protection from the weather.
2. Listed the event online (using osmcal.org) and spread the word (via local OSM community mailing lists).
3. Downloaded OSM data for a before and after comparison (through JOSM).
4. Made obvious improvements and filled in the existing OSM data from aerial imagery in preparation.
5. Printed paper maps (from Field Papers and screenshots of JOSM) and got stationary.

Field Papers makes it easy to generate paper print-outs, but the result is not as useful as what I produced by taking a screenshot of the data carefully set up in JOSM. Seeing all of the OSM data over slightly washed out satellite imagery makes for more accurate notes than any of the styles that Field Papers offers. The Field Papers grid also leads to features and areas being awkwardly split across multiple pages, and the QR code covers an area of the map that isn’t included anywhere else. Manually combining JOSM screenshots allows me to get just the right area on each page, but is fiddly and time consuming. This is a process I am looking to improve.

Given the state of OSM data in the area, there was a lot of cleaning up to do before showing up in person. I found this to be time well spent for a few reasons:

• It avoided double handling a lot of geometry (tracing buildings and paths on paper, just to trace them off imagery later).
• It enabled an “assume but verify” workflow, where I could make assumptions about building and path geometry and some amenities, from the imagery, before verifying them on the ground and only taking note of any changes that need to be made.
• It made positioning surveyed features easier because there were more details to relate to.
• It created a whole lot of quests in Street Complete.

There was also a lot of editing to do after the event, putting in all of the information recorded on paper, and resolving data conflicts and tagging mistakes from the day. We didn’t co-ordinate these edits at all, which was not a big problem, but I would have liked to know what to expect from the other mappers.

I did not plan for any follow up contact, which I feel was missing. For future events, I would like to talk about the “what next” aspect after collecting data to

• roughly co-ordinate uploading of paper notes,
• encourage new mappers to view the features they have added later in iD to make tweaks and get more context about the changes they have made, and
• set a schedule for when I (as the coordinator of the event) will go through to fix conflicts, fix mistakes and generally clean up.

I would also like to collect contact details from participants in order to ask for feedback and to share a nice summary of the our achievements with a nice before-and-after comparison a week or so after the event. (I am still figuring out how to produce good before-and-after images and statistics and would appreciate any resources to help.)