All language subtitles for 07_flow-maps.en

Flow maps are used to show the path of a quantity of something,

through space or over the surface of the earth.

So, here's a nice example of a flow map.

This is an oldie but goodie.

This is from 1980,

but it shows the international crude flow, in barrels per day.

I really like this map because all it does is what a flow map is supposed to do,

which is show linear movement between locations.

So, for example, you can see that there's a heck of a lot

of oil coming out of the Middle East which is what you would expect,

and the thickness of the line,

represents the amount of oil that's being shipped.

So, the thickness of the line splits because part of the oil is going to the west,

part of it's going to the east. So, we can see that.

We can see the route that's being taken.

Now of course, this isn't meant,

so you're not navigating an oil tanker with this,

but you get the general idea of how that oil is traveling

from one place to another and how much of it is traveling from one place to another.

That's really what a flow map is good for,

that's what it's meant to show.

So, the width of the line is proportional to quantity,

and the idea usually,

is you're trying to show a route that's being taken.

Now, the direction may or may not be indicated.

So, for example, this is a traffic flow map,

but its traffic flow in both directions.

So, the thicker the line the more traffic,

and you get this, I think it's borderline.

It's a nice spider web effect or network effect,

but it gets a bit much in this area here where it's hard to tell what's really going on.

But it does send the message that there's a lot of

traffic in certain areas and not so much in others.

Really, the main point of showing this one is just to show that,

flow maps don't always have to show the direction of flow.

It can just be the quantity of flow based on the thickness of the line.

This is an example of a not-so-great flow map that I like to include.

Because I think the map creators had good intentions and some really interesting ideas,

but it may have just fallen apart a little bit along the way.

So, let's see if we can break this down a little bit.

The first thing that I notice of this,

well one of the first things,

is that they're using what looks like an azimuthal projection.

So, those are typically used for the North Pole, or something like that.

If you look at it, so we have the UK here,

and we have this distorted effect,

coming out from there,

because they're using this azimuthal projection.

So, right there, that's a projection that people are not as used to seeing,

it's not as common.

So, that might be a little bit unusual.

Then on top of that,

they've got these different size circles.

But they haven't got anything in the legend as to what those are,

so they may be graduated symbols or proportional symbols,

but we don't really know what they are.

Then on top of that,

they have these flow lines,

which aren't bad really in that, yes,

you can see them, you can see what the flow values are,

some are bigger than others.

But a couple of things here that aren't great,

is one is that the arrow,

they're trying to show flow in both directions.

So, this is one direction.

Sorry, that's the arrowhead there.

There's an arrowhead there. But, because the arrowheads are too small,

you can't even really tell one direction versus the other.

The other problem with this I think is that,

you end up with this striping effect,

especially around here, when they've tried

to show these matched lines in both directions.

Again, an interesting idea.

But, it becomes really confusing,

a little hard to read when you have that on top.

Then the last thing, is with these dotted lines here.

I don't know what those are either.

They are not in the legend. They're not explained.

So, we've got a lot going on here.

Like I said, it was a very,

I think an ambitious map.

Somebody was really trying to pack a lot of information into one map,

but I don't think that they really pulled it off that well.

In terms of designing flow maps,

one of the things to keep in mind is the legend.

There's lots of different ways to show how

the quantities of flow are related to what you're seeing.

So, it could be just by the thickness of the line,

like you have here in here.

Sometimes you something creative like a ramp like that,

or a staircase effect.

So, I'm just showing these to give you a sense of

different ways that you can show this in a legend.

None of these by the way are available in ArcMap,

or ArcGIS in general.

Flow maps are actually difficult to create.

There's workarounds or ways that it can be done,

but it's not something that's very easy to do,

just off the shelf.

This is an interesting example,

of a flow map.

I like to put this in here,

because there's some interesting ideas, some good intentions,

but it's not quite as good as map,

as it may seem.

What I mean by that is that,

what you want to see here is flow.

You see these thick lines that represent more flow,

thinner lines representing thinner flow.

This is actually an interesting dataset,

and an interesting idea,

is this was from a guy named Eric Fisher,

and as reported in national.

I'm just going to read a little bit from that,

it says, the project laser,

around 10,000 geotagged tweets,

and 30,000 point-to-point trips,

in cities like New York City.

This happens to be drawn all,

with the different ones,

to plot the flow of people in terms of favored paths.

Using a base map from Open Street Map,

he drew out transit paths, using tweets.

That's what they call these as transit paths.

Movements are indicated on the geolocation of a tweet,

with an individual star point marked with one geotagged tweet,

and ending with the next geotagged tweet.

This is what creates a mass of traffic routes.

Now, I'm not going to go to a big critical analysis of this.

But essentially what they're saying as far as I understand this,

is that if somebody had a geo-located tweet, in other words,

they shared their location with that tweet at one location,

and then they did that again somewhere else,

that it was then assumed that they used transit to get from one place to another.

Then that was, added to the map as though,

this person went from here to here.

We're assuming that this is the route that they took,

because they have no way of knowing that.

All they have is the start point point the endpoint.

Then this over and over again for thousands of tweets,

and then you end up with a map like this.

They're saying look, you can see all the transit routes.

There's actually things in here where people are saying,

you could use this for transit planning.

I don't know about that. I'm not trying to dump all over this map.

I think it's an interesting idea.

I think social media can be a useful source for data mining.

But we have to be very careful about making

assumptions or leaping ahead beyond what the data really supports.

So, I think generally speaking,

this might be able to be used in some way.

But unless you are able to see somebody's route like let's say

you had a GPS that was pinging

every minute or something along a route or something like that,

so that you could actually track their real root that they were taking,

and the way that they were taking it,

then yes that would be great.

But when you're trying to infer from,

geo-located tweets that we don't know how far,

how long apart those were.

Like what if they were the next day or was it within an hour?

Were they driving? Were they on a subway?

Were they are on a bike? They might take different routes for that.

So, like I said, I'm just trying to encourage you to have

a healthy and useful constructive form

of critical thought analysis about these things when you see these datasets,

that they're novel, they're interesting,

but we also have to be careful about,

what is it that we can really get out of them.

So, if you want to have a look at this,

there's a website for this,

it's actually through Flickr.

So, you can search for,

pass through cities, and he's done it for a lot of different cities in the world.

I think there's some really interesting stuff in here.

It's very thought-provoking.

But we just have to be a little careful about what we're interpreting from it.

This is one one my favorite flow maps.

I love this implementation of

a flow map because they're actually using animation to show flow,

as opposed to just showing it based on the thickness of a line or something like that.

Not only that, but it's interactive.

So, we can easily manipulate the globe,

to be able to look at any particular location and look at,

what we're seeing here,

are wind speeds and directions,

at the level of the jet stream.

So, if you're not familiar with weather patterns.

I'm not in any way an expert on this.

But I'm fascinated by watching things like the jet stream which have a big effect on,

say whether in North American certainly in Canada.

This is updated in near real time.

I think it's several times a day that it's updated.

So, you can very easily see by the speed of the animation,

by the color of the animation,

that we have varying quantities in terms of the amount of wind that's going on,

the force of that wind.

So, not only that,

but we can actually modify this.

So, if we change the height,

for example here to 1,000,

this is I believe millibars,

then we can see surface winds.

So, we can actually zoom in here.

For example, we can look at surface winds around

the Great Lakes right now or not that long ago.

So again, this is a nice way of being able to visualize flow.

I can look at this thing all day.

I notice that, this particular flow map was being used for talking about hurricanes,

during the hurricane season on some of the networks now.

So, I think that they're getting used to the idea of being able to

show more sophisticated visualizations which is awesome to see.

I'm so glad they're doing that.

So, as we move around here,

you can see different weather patterns going on.

This could be used to explain the weather forecast at any particular location.

So, I just thought this would be a nice one one put in here

to show that not all flow maps are static.

Not all of them are out of old cartography textbooks.

There are some really innovative,

interesting ways of showing this data.

I do think this is a useful dataset in that,

it helps us to understand something even better.

It's not just a matter of taking a bunch of

data and throwing it on a map and saying, look what I did.

Instead, you're actually seeing a process in action.

You're seeing wind speeds at different heights and

you can relate that to what's happening with weather,

cloud patterns, temperature, there's other things,

other variables available through here.

So, it's actually way of informing the map reader by helping

them interrogate the data and explore it in interesting and novel ways.

This is a very useful flow map to visualize the movement

of refugees from various countries to other countries. I quite like this one.

It's a fairly simple map in a way,

but it's very effective in showing

the quantities of people streaming from different countries to other countries.

So, you can see where they're coming from, where they're going.

The general direction, it's not the absolute path that they're taking.

But you can actually see where they're coming from and where they're going.

You can also see it in relation to this timeline,

here at the top so it's interactive.

You can actually change the time and see the quantity that's taking place.

So, for example, if we go to here,

and then watch the animation,

you can see that the numbers get much higher.

We can look at different countries and say for example Russia,

versus let's say Egypt, or Syria.

So, you can see quite a few people obviously leaving

Syria and heading to various countries in Europe.

So, this is a way of showing a flow map that helps to

understand which countries are

being affected in terms of people leaving or people arriving.

How many of them?

How quickly? At what point in time?

So, it's not a super sophisticated map in a way.

It's just an outline of the countries with some dots streaming across it.

But I think it's very effective.

It's got a really good impact to it,

because if you're not familiar with that situation and with

the fact that these refugees are moving in really large numbers.

This is such an effective way to be able to show that

the quantity of a data value and the flow of that data,

and the direction of that data, for those people.

So, I think that's a nice way of being able to

show that I just wanted to use that as a good example of a flow map.

So, that's it for flow maps.

I just wanted you to know what they are,

how they work, what their for.

The fact that we're trying to show volumes

of something moving from one location to another,

potentially with the direction and the path that has been taken.