Mapping

Previously I wrote on preparations to map Summerhaven for OpenStreetMap (OSM). This weekend we were able to get up there, drive around and take pictures. Here is the map as of yesterday:

And here is the map today:

As you can see there are less roads. We found that many of the roads just don’t exist. Also after talking to some cabin owners we met, some roads have apparently been cut in two to build more cabins.

Comparing with the Google map we can see that we have missed a section of roads in the North East of Summerhaven, so we will need to go back for those sometime soon. Looking more closely at the Google map I can see many mistakes. Roads connecting when they don’t and the wrong names used.

Interestingly it seems Garmin have also used the incorrect TIGER data for their City Navigator NT. It contained a huge error which I corrected as soon as I saw it several weeks ago on the OSM map.

We marked on the map the locations of restrooms and parking areas, something which doesn’t appear on other maps.

Here is a screenshot showing our GPS trails overlaid on the TIGER data. As you can see the TIGER data is total nonsense.

We have now compiled a list of about half a dozen specific items to look at when we next visit, however I can say that the OSM map must be the most accurate map of Summerhaven that is publically available, even if it isn’t completed yet.

I’ve decided to write down my goals. These are long-term; if I can get them done in six months that would be great.

1. Large Scale Features

Adding national forests, parks and preserves, wilderness areas and the trails inside those areas for Arizona. I am perhaps 70% done with this goal. The benefit is vastly improved recreation maps for the six million people in the state. The area is huge (larger than the UK) and the total number of nodes is probably in the 100,000s.

2. Medium Scale Features

Adding key features in the city of Tucson. This includes major rivers and washes, large buildings such as hospitals, malls and big box stores, realigning primary and secondary roads. To date I have added at least one of each of these features. The benefit is a good overall map for the one million people who live in the Tucson area.

3. Small Scale Features

I plan to completely map in as much detail as possible the nine square miles or so around my home. This includes realigning all the streets, adding buildings which are not houses, adding recreation areas, ensuring all streets are named, etc. Of the three goals this is probably the most work. The number of people living in the area isn’t that much, but I intend this to be an example for future Tucson mappers.

Finding out which tags to use when can be difficult. JOSM includes a presets menu that helps, but what is the difference between landuse:retail and landuse:commercial?

I had an idea of the difference but before using these tags for the first time I needed confirmation. After some digging I found the Map Features page in the OSM wiki. It confirmed my thoughts. Retail = shops, commercial = offices.

Open Street Map (OSM) is a world map that anyone can edit, just like a wiki. I used the data in a few projects but seeing as the US road system was generated from a mass import of US Government data, I thought that it was largely complete and not much to do. This was, of course, wrong.

Back in May I was in East Yorkshire, England and I added a trail to the map.  A local OSM mapper contacted me about it. When I got back to Tucson, Ariz. I was inspired to look more closely at the local data to see what was missing.

I found that most of the streets were not aligned correctly. Also the National Forests were missing, plus a nearby National Park. There is a lot to do in the US, that’s for sure.

I started off by realigning the streets in my area and completed four square miles. But what really interested me was the forests. A bonus is that US Government data is in the public domain and can be freely used for OSM.

I’ve now spent the last month, off and on, working on this. So far I have added all the National Forest boundaries in Arizona and New Mexico, some grasslands in New Mexico and Oklahoma and a Nature Preserve in New Mexico. I’ve also added Saguaro National Park East and the trails in the park. Currently I am working on adding the Wilderness Areas for Arizona and New Mexico and the forest trails.

I encourage you to take a look at the map in your area and see what you can do!