OpenStreetMap
You’ve probably already seen the video of the Fukuoka sinkhole swallowing up large parts of an intersection. This obviously necessitates a map update, as it could be a little bit of an inconvenience to drive on this stretch.
In Japan updates are quick, both on the map and in the real world. From the detailed traffic restoration plan the road might actually be back to normal before any other map gets updated ;)
Wikidata, the crowdsourced database of structured knowledge by the Wikimedia movement has grown to over 24 million entries and by now has structured information for every major settlement on earth. These are extremely useful properties like multlingual labels, statistics like populations and GDP, and other related information like politics, history and media about the place (See London, New York City, Timbuktu).
Geolocated articles on Wikidata, with those added in the last year highlighted in pink. Source: Wikidata Map
Might depend on what exactly one considers a point of interest, but looking at some common keys:
we get around 20 million features that could be potential landmarks or points of interest.
Just counting points that have names, we get around 12.9 million features.
Addresses
70 million individual addresses and 49 million postcode locations
Maybe there is a better way of finding out, but here’s a new conversation starter at your next mapping party!
Found myself at the Royal Observatory this morning (on the map), and discovered a bit of trivia since I expected to be located at longitude: 0°0 as my geography class would have made me believe. Well, its not:
Prime meridian at Greenwich. CC-by-sa ChrisO
The prime meridian established at the Royal Observatory, Greenwich in 1851 is actually at 0°0′5.3″W, thats 102m west of the the 0°0 prime meridian used in the WGS 84 coordinate system. Why? Because the modern coordinate system was corrected to have its origin at the Earth’s centre of mass.
Read more at https://en.wikipedia.org/wiki/Prime_meridian#International_prime_meridian
There is an open dataset of turn restrictions in Toronto which gives a rare opportunity to completely map every restriction in the city.
Inspecting the dataset in QGIS
The dataset consists of the topology of road centerline of every junction in the city, and at every junction, each possible turn direction is an individual line with a property that indicates the type of restriction on it.
Most of the restrictions are u-turns and no turns into one ways. The only restrictions which look valuable to add into OSM seem to be the no turns (By law) which number about 520.
While tracing an area of continuous buildings in India, realized there was no easy way to create such a pattern of features in JOSM.
How does one split a group of ways using an intersecting line. The More Tools>Split Object command comes closes but works only with a single way and line that it encloses and is quite laborious.
Terracer plugin does not work well since the area is not a perfect rectangle, so it does not get the axis right. Any other editor/plugin capable of drawing this quickly?
A new user accidently added addr:city and addr:province tags to a large selection of objects, including rivers and individual nodes.
The user mentioned that the tags were intended only for buildings, so thought I would document the cleanup for future efforts like this.
It is possible to extract all objects with addr:city added by the particular user using this Overpass query.
There is some interesting research on the validity of polygons/area features mapped on OSM by Jochen Topf the creator of the osmium suite of OSM processing tools. There seems to be two major problems:
In his usual style, there exists an in-depth explanation of the problem. Bonus is a chapter on OSM polygons and how they are rendered for GIS nerds.
Of the over 220 million (multi)polygons in OSM more than 100,000 contain mapping errors of one kind or another and about 250,000 are tagged old style with tags on the outer ways instead of on the relation making multipolygon tagging and processing much more complicated and much more expensive than it needs to be. Read more
I dug into the dump of invalid polygons and inspected it in QGIS to get an idea of the breakup of issues to see if they can be prioritized to fix:
A rather inspiring story came to my notice last week on World Environment day from Chethan during lunch, that of a lady who mothered thousands of trees just like her own children in rural India, not too far away from here in Bengaluru.
Saalumarada Thimmakka has planted over 8,000 trees, the most famous being 384 banyan trees on a 4km stretch of road from her home village Hulikal to Kudoor.
A bunch of us mappers Chethan, Maanya and Ramya plan to take a ride out of the city to meet this amazing lady and plant her banyan trees on the map!
Found this oddity through Chetan, that I never recalled seeing before.
At first thought someone squared a border, but this was created 4 years ago and is a disputed border area between Chile and Argentina.
Not been able to find many maps that show the border like this, but here is some interesting reading:
| NYC had an import of over 1 million building footprints and 900,000 addresses in 2014 from the New York City Department of Information Technology and Telecommunications (DoITT). The DoITT GIS releases an updated shapefile of the footprints every quarter, and the latest version can be accessed here: Building footprints | Address points |
Open datasets like these are a great opportunity to explore how OSM can be used as a bridge between authoritative information and that crowdsourced by citizens. Two years after the import, it is interesting to see how the OSM data compares with the latest official footprints. The interesting questions to ask is:
Iquitos is a city of 370,000 in the middle of Amazon jungles of Peru without a road connection with the outside world. Found it while investigating routing failures in OSRM.
Here’s a great travelogue of this fascinating place while trying to research possible car ferry connections. There are none.
Maps lead you to interesting places :)
Hello Kitty
Quality assurance in OSM is a pretty hot topic. The first question when first faced with the concept of a map that anyone can edit is - how can one guarantee the quality of the data?
In a constantly transforming world, the fact is that its impossible to gaurantee any map in the world is accurate unless it was physically surveyed recently. And the reason why OpenStreetMap has such high quality of map data for many parts of the world is precisely because this project allows anyone to update the map so easily. And to ensure quality, we just need more users of the map for that location, an empower them to update anything that does not match reality.
For this to work effectively its obvious we need to make it as simple as possible for map users to spot mistakes and make an update. Some interesting data incidents that were caught by the community recently:
One of the main reasons I was convinced of the power of OSM when I first started to edit 8 years ago was the possiblity of seeing maps in my native language Tamil, spoken by 70 million people, which was till then unheard of. This is a huge factor in making technology relevant for people on the ground and breaking the notion that one needs to be literate in English or the Latin alphabet to be able to use modern tools like interactive maps.
There have been numerous experiments at making multlingual maps in India, I remember Yahoo maps having Indic streetmaps for India in 2007, but was soon discontinued. Google Maps for India is primarily in English and even in OSM we use the name tag to record the name in the Latin alphabet for consistency. India has 22 languages, none of them universally understood by the whole country. Even the national survey agency makes only English maps, with a select few created in Hindi.
Always satisfying to go into the map and add some sugar. Especially in the town centre.
This is the main station in Thiruvananthapuram a city of close to 1 million in India.
The description of the railway=halt wiki, says:
A place along a railway line where trains stop. It’s not a station because it has no switches.
If we take this to mean that trains cannot crossover at this facility, then most subway/metro stations should actually be tagged halt rather than a station.
This actually makes a lot of sense since stations with crossovers/switches are usually more important in the railway network like junctions, terminals and crossing stations. Proper tagging of subway stations as halts will help to bring better hierarchy among the stops in the system.
Im going to try retagging the stops for the subway in my city and compare the results.
Kottayam in the state of Kerala, India is surrounded by intricate systems of wetlands and navigable canals connecting it to surrounding villages. Tried my hand at understanding the network and tracing out some features.
Made this gif around a year ago for someone asked me how to trace parking spaces. After trying different methods and plugins, I found this to be the simplest workflow:
Is there a quicker way? please share.
This handy feature in JOSM fetches the titles of visible imagery layers that you have loaded into JOSM and adds it as the changeset source.
Never knew it existed till someone pointed it out to me. Hope you find it useful.
Just found that the raw satellite imagery from ESA’s Sentinal-2 project is now open. The resolution of the imagery is 10m/pixel, so not good enough for street level detail, but can be quite useful to monitor vegetation changes and infrastructure construction progress since the update cycle seems to be around 1 month.
Band 8 imagery with false color mapping showing the 5km long Bandra-Worli Sea Link in Mumbai
This is a great source for multiband imagery that you can use to do some interesting raster analysis in QGIS.
EU law grants free access to Copernicus Sentinel Data and Service Information for the purpose of the following use in so far as it is lawful4:
