It's a simple, but powerful concept: asking a bunch of people to mark stuff on a map.

We call it "collaborative and crowd-sourced mapping", or "crowd-mapping" but there are many other names:

• VGI - Volunteered Geographic Information
• PPGIS - Public Participation GIS
• Neogeography
• Participatory Geoweb
• Community Mapping

What do these methods all have in common? They all involve asking people "where". They are enabled by widespread access to the internet, web-mapping technology, rising technical literacy, and social media.

Let's talk about what we mean by crowd-sourced mapping, and why we think it's so cool.

Types of crowd-sourced spatial data.

It's important to understand the main two categories of data that can be generated through crowd-mapping methods: objective, and subjective.

Objective spatial data

OpenStreetMaps is the most successful and popular demonstration of the power of crowd-mapping for gathering and editing objective spatial data. By objective, we mean data that represents real physical objects and boundaries: like businesses, trails, trees, houses and city limits.

Thousands of self-organized teams and communities of editors like Youthmappers and Humanitarian OpenStreetMap Team have helped generate millions of contributions for even the most rural and far-reaching corners of the Earth. These contributions are added directly by locals themselves, or by people tracing satellite imagery by hand-- this is why OpenStreetMaps has become such a valuable and comprehensive resource for geographers, app developers, planners and GIS analysts. If you use services like Mapbox, Leaflet, Maps.me, or even Apple Maps, you are looking at OSM data!

While canvis.app could be used to collect objective data which might be relevant for OSM, we don't plan on directly integrating with OSM. This is because OSM contributions have precise requirements-- take a look at one of the many OSM editing tools.

There are many examples of objective spatial data that doesn't fit on OSM-- some locations, like potholes or broken streetlights, are temporary and transient. Other examples include biological resources (an invasive plant, an endangered bird nest), or small and "hyper-local" things like small bike racks, power outlets, paper signs. These things might be too numerous, or they might only be interesting for select groups of people.

However, just because something doesn't belong on OSM or Google Maps, doesn't mean it isn't worth mapping. You might be an urban planner, or a biologist, or a researcher, or a community activist. You might want to employ the wisdom of the crowd for mapping for your own unique purposes. This is precisely why we created canvis.app!

Subjective spatial data

It sounds funny, but even if a data point doesn't represent anything in the "real world", it can still be valuable. What sort of subjective information can we put on a map?

• Opinions - "I hate this intersection. I love this park."
• Perceptions - "I feel unsafe here. It's nice and quiet here."
• Desires - "I wish there was a bike rack here. We should expand this sidewalk."
• Experiences - "I was assaulted here. I saw an endangered bird here."
• Ideas - "What if we put a transit station here? What if we blocked this lane?"

These are all tied to a very real and precise geographic coordinates. Interestingly, this sort of information is sometimes best collected "in bulk"-- we might not care so much about the desires and perceptions of one random citizen, but together we can understand and engage the community as a whole. This is where crowd-mapping and web-maps come in.

Why web-maps?

Even if you see the value in collecting and analyzing the types of data described above, it's still fair to ask why bother putting it on a web-map?. After all, spatial data is just an X number and a Y number with some attributes attached. Wouldn't it be easier to just collect it through survey forms or spreadsheets?

In some cases, yes. For small or frequently changing sets of data, or between a small number of contributors, crowd-mapping methods are not the right choice. We created this knowledge base to help you decide for yourself.

Here are some good reasons why you might choose to do a collaborative or crowd-sourced mapping campaign:

Maps are a resource.

Take sexual harassment reports, for example. I might see statistics about the number of reported crimes in my city, or I might listen to a victim tell their story on TV. Maybe I could download the big long list of police reports and read the address for each. None of these will have the same impact as being able to zoom to my neighborhood and reading the reports in my favorite park or place.

By being able to zoom, pan, click, read, comment, and share, spatial data becomes much more valuable to me and my community as a whole!

Maps are familiar.

We are now a very tech-literate and "cartographically literate" society, some of us using navigation apps on a daily basis. We can quickly and easily locate ourselves and familiar points of interest. And when we can't, we have magical geolocators and search boxes to help us along.

With this familiarity comes creativity and inspiration-- asking somebody to simply name a location can elicit a very different response than if we were to place a map in front of them and ask them to mark it.

A diverse, dynamic, powerful tool

Hopefully, this brief introduction explains what we mean by crowd-sourced web-maps.

Can you think of any apps or products that offer a crowd-mapping functionality? There are some wildly successful examples, like Waze, which started off by allowing people to mark traffic information, and see it on a map. HarassMap has been operating in Egypt for many years now, and served as an important part of the organization's efforts to fight for women's rights. Other examples include PooperSnooper, SeeClickFix, and countless other apps and websites built for mapping everything from toilets to yardsales.

Continue to the next article to learn how canvis.app let's you build and launch your own-- without the budget or team of programmers!