Hello, my name is Mr. Conway.

I'm very pleased to have the opportunity to guide you through today's geography lesson.

The emphasis is going to be very much on use of geographical information systems, otherwise known as GIS.

So let's get started.

This lesson is part of the GCSE geography units, which look at development and the gaps or inequalities in development.

So by the end of today's lesson, our closely linked outcome is that you'll be able to use GIS desire lines to visualise migration.

You'll be learning some GIS techniques which have wide application across geography.

And some of the learning may be new to you, but I'm here to help you along the way.

To help us achieve the outcome, we need to learn or remind ourselves about certain keywords.

These are the keywords for today's lesson: desire lines, filter, great circles, and pop-up.

So let's look at the definition of these keywords in little bit more detail.

Desire lines are a graphical technique using lines on a map to show the simple direction of movement from one place to another.

A filter is the selection of data in GIS, and it means we can declutter a layer of data in a webmap to visualise spatial patterns more clearly.

And this is because GIS often deals with very big data sets.

And filters can help us to look at the things we're most interested in.

We might say it helps us to see the wood for the trees.

Great circles are straight line routes which appear to be curved on 2D maps because they take the curvature of the Earth into account.

A pop-up is a tool we use in GIS very often, which provides read-only information about the attributes in the data set which sits behind it, and that could be text, or images, or charts, or all of those things.

And it's often linked to a particular location.

So it's geo-referenced.

There are gonna be two learning cycles for this lesson looking at how we use GIS desire lines to visualise migration.

So we're going to look at the first of these learning cycles now.

How can GIS desire lines visualise migration? The movement of people and goods can be shown using two types of GIS lines: desire lines and flow lines.

Desire lines show a simple link between a source and destination.

Sometimes this is referred to using the expression, "as the crow flies." Flow lines, on the other hand, show the route, the actual route taken between a source and destination.

So this could be, for example, by road, or rail, or even by sea.

At an international or global scale, such as this world map or any large scale map, desire lines are more useful than flow lines to visualise migration between source countries where people are migrating from to a destination country where people are migrating to.

As happens with big data, for many countries, the visualisation can become rather overwhelming and cluttered.

So although desire lines can create powerful visualisations, we may need to manage the visualisation to be a bit selective.

So how can we use things called GIS filters to declutter a map with many desire lines.

Here we can see how just three desire lines have been selected.

We're gonna find out quite a useful way to do this.

Another interesting aspect of desire lines is that they take the curvature of the Earth into consideration for us.

GIS does this by showing desire lines as what's called great circles like this.

Great circles are straight line routes which appear curved on a 2D map.

Here's a video guide to show how we can use GIS desire lines to visualise migration.

This guide is going to show how to create desire lines for migration using GIS.

In order to do this, we're going to use a map called Migration_2.

And if you are able to sign into ArcGIS online, you can save all your work yourselves on that map.

So this is a ready-made map, and you can see we've opened the Layers panel.

If you can't see that, just open it by clicking Layers on the top left there.

And several layers are there, including one that hopefully you can see already.

In case not, I'm just gonna make it invisible, then visible again, which is the UK.

So we've got one point in the UK, which is the destination for the migration that we're studying.

In this ready-made map, one of the other layers is of course immigration UK 1990-2020.

And we can switch that on to see that it's referring to all these places in the world from which there might be migration to the UK.

We're gonna switch it off for the purposes of what we're doing with creating desire lines.

So the layer is still there, I've just made it invisible.

The next thing we're going to do is go to the UK destination country layer, which is the single dot in the middle of the UK.

Just gonna switch it on and off so you can see it's there.

And then we're gonna click the options at the end of the layer name to click Show Properties.

And we're going to use the analysis tools, which is this icon on the right-hand side.

We're going to click that once, and it will show you some options for analysis tools.

And we want this group of tools here.

When we click that, there are quite a few of them, if we click this and see what's an offer.

And they're in groups here, so you can see they're in dropdown menus.

And the dropdown menu that we are interested in here is called Use proximity.

So we scroll down to that one and click Use proximity.

And the option we want to choose is called Calculate Travel Cost.

In spite of its name, this helps us to create desire lines.

So if we click that, it then invites us to say, "Okay, where do you want these desire lines to come from in the From Layer, and where do you want them to go to? So the place we want them to go to is the UK.

So if we click that one first, we can see it says UK destination country points.

So if we click that, we've told it where we want to go to.

And we want the layer to come from the immigration point layer that we glimpsed earlier on.

So we're gonna click that.

And then we have told it where we want the desire lines to go from and to.

Then we need to scroll down in the panel to Analysis settings.

And instead of Drive Time in Measurement type, we need to select Line distance.

And that will calculate the distance.

And it will also draw a straight line from one place to another to create our desire lines.

We then need to give our layer a name, and it's gotta be a unique describer.

So we're gonna call it desire lines to the UK.

And you have to wait a while for the desire lines to be created because a lot of data is being processed.

There's a View Status bar which we can click to see how that's going.

And this can take a little while because it's generating a lot of data for desire lines for lots of places.

So you just have to be patient until it's finished.

And when it's created the desire lines, it's quite a spectacular outcome.

So we just close that panel and the panel on the left.

And we can see we've got desire lines from all of those possible destinations to the UK.

So we've created our desire lines, and that's good work.

So let's make sure we save it.

I'm gonna save this file now, but you can save as with a different name if you want to, perhaps add your initials at the end.

So there's a lot going on on this map.

And of course we can see the desire lines are showing the great circle route from each potential immigration source country to the UK.

But the variation in the number of immigrants coming from the different source countries will vary tremendously.

There'll be some countries with hardly any, and there'll be some countries with very large numbers.

So how can we prioritise that among this very large collection of data? Well, there are two ways of doing it.

The first one is to use a filter.

Let's see how the filter works for this data.

First of all, in layers, we click on the options for the desire lines, and then we click Show Properties.

And what we can then do is click Filter on the right-hand side.

And we're invited to add a condition called Add new for the filter.

So we go Add new, and the Condition panel opens.

And this we're going to filter by the rank of the countries to try and see if we can just see the top 10 countries of all the countries in the world that are shown here.

So we click Route Name, but we don't want that.

We want the rank.

And we move down to where we can see that.

And it's difficult to find.

There it is.

So rank 2020, yes, that's the one we want.

We click that.

And then a histogram appears.

And it's defaulting to show rank number 103.

You can see it just there.

But we just want to see the top 10.

And what's really quite good about this is you can actually see them by filtering it.

So if we then say we want the filter to be less than a certain number, and because we want the top 10, we're going to say less than 11, it just shows us the top 10.

Before we actually finalise that, just gonna show you how the filter works, almost like a transparency slider.

So we can move through and see a progression of which countries in the world are ranked more or less highly for migration to the UK.

And I'm gonna scroll back, I'm just going to shut that window down so you can see that a bit better.

So I'm gonna scroll back now.

So we're moving towards the top 100.

And then we can move a little bit further, and we probably can see the top 50 or so.

And then we can move down to see the top 10.

And it gets a little bit difficult to use that there.

So I'm just gonna use these buttons here to go down exactly to number 11 'cause it's going to be less than that, which will be the top 10.

And there we have it.

So we can then click Save.

And we have our top 10 countries for immigration to the UK shown quite clearly.

So let's just save our work.

Soon you'll have at the opportunity to create desire lines to visualise migration yourself.

But let's just check up on some points from the video demonstration.

Here's our first check.

When using Map Viewer, which of the tools helps us to declutter a webmap by selecting data using what's called a condition such as is greater than? You may wish to pause the video here and then restart it when you selected your answer.

Well done if you selected filter.

Now for a second check, it's a true or false this time.

Is it true or false to say that desire lines and flow lines are two different names for the same thing? You may wish to pause the video again here and restart it when you've decided if this statement is true or false.

Okay, this is actually a false statement.

Why would that be the case? Once again, pause the video if you wish.

And restart it when you've decided why it's false.

So desire lines and flow lines are not the same thing.

They're often muddled up.

It's important not to do that.

The difference between them is that desire lines show a simple link between a source and destination, whereas flow lines show the actual route taken between the source and destination.

Now for the tasks which are going to help you to create desire lines to visualise migration yourself.

For these tasks, you're going to need to open the link provided which takes you to a ready-made webmap called Migration_2, and then sign into ArcGIS online so that you can save your work.

In task one, you're going to create GIS desire lines to visualise migration.

As a follow-up in task two, you'll find out how to declutter your desire lines by using a GIS filter using source country rank in 2020.

And you can see a GIF here which gives you a clue as to how that works.

Have a look at that if you want to get some further details.

So pause the video now to take some time to untake the tasks.

And when you are ready, press Play to obtain some feedback on the tasks.

We'll see you on the other side of the tasks.

Hopefully the task went well for you.

For task one, your webmap desire line should look something like this.

The visualisation is quite spectacular because the GIS desire lines are using great circles.

For task two, you use the filter tool to declutter your map so that it only shows the top 10 source countries.

So it should look something like this.

Hopefully you agree that that does simplify the map and declutter it effectively in a meaningful way.

If there's anything you're unsure about there, do take another look at the video demonstration.

Our second learning cycle is going to show how desire lines can be made more powerful by being configured.

To show the amount of migration, desire lines can be drawn to be proportional to the number of migrants as with any other proportional symbols.

By doing this, we've effectively visualised source countries with more migrants and those with fewer migrants.

But we can do more.

It may be useful to show each country in a distinctive way.

The visualisation can be enhanced by configuring the desire lines using colour coding.

And if we do this, we can also add pop-up details for each country.

So how can we configure desire lines using GIS? Let's find out in a second video demonstration clip, which shows us how to configure desire lines for migration using GIS.

We're now gonna see how we can configure our desire lines for migration.

We filtered the lines to show the top 10.

But how can we show the lines proportionally? So vary their width according to how many people are migrating along that route.

We go to the Layers button, and we find that our layer that shows the desire lines, I'm just gonna switch it on and off, and make sure it's on.

Then I'm gonna click the Properties panel for it, just here.

Then we're going to go to Edit layer style in the section Symbology.

So I click Edit layer style.

I'm going to delete this destination ID and then go to the Field button to search for attributes I want to show.

So I click that button there, and have to scroll through and look very carefully until I find the one that shows the 2020 immigration numbers.

That's this one here.

I'm also going to click the button for the source country so I can show those two pieces of information, and then click Add.

So now the lines have been drawn proportionally, we can already see that's quite useful.

And they've automatically been color-coded according to which country, which is also useful for visualisation.

But we can do a little bit better than that.

So we're going to go to number two, Pick a style, and we can then click the Style options for counts and amounts size.

We scroll down and untick where it says Adjust size automatically.

And we're going to change the size range from five pixels, which makes the smaller ones, smaller lines a little bit thicker.

And we're gonna make the largest lines 15 pixels.

Now, we can see the visualisation is improved considerably.

What you can do as well is change the colour ramp if you really want to.

So click that Done.

We go to Types unique symbols, and you can change the colour ramp here if you want to.

I'm not gonna do that because I think that actually is quite a reasonable colour ramp.

So I'm gonna leave that as it is, and I'm gonna click Done, and Done again, and Done again.

You have to click that three times.

And then we can click the Legend to see what our key looks like.

So we've actually got color-coding for all of the countries in the top 10.

And we've also got the amounts here in terms of the line width.

So that's quite a good outcome.

So we're now gonna save our map again.

Finally, what we're gonna do is configure the pop-ups.

If we click on the desire lines at the moment, they're not terribly useful.

We can make them better than that.

They're full of information that's useful.

But some of it, we don't need.

So what we're gonna do is try to configure the pop-ups for those.

So we head for the Layers panel here.

Once again, open the properties for our desire lines.

This time we're going to go to the Pop-ups section just here.

So we click Pop-ups.

And then we're going to click Title.

And this particular title, we don't want.

We're gonna type something else instead.

We're going to click that and type in From_Source_Country.

And what that does is pick up the name of the country from the dataset, but we put from in front of it, and you can see that started to appear here already.

So this panel will show you the progress of configuring the pop-ups.

So as we can see in the pop-up, by default it's showing all the fields.

So we can delete those.

So it can put the fields in that we would rather show.

And we're gonna add content here and click Text.

And what you can do is then type a formula of words to pick up the information.

So we're going, so we want to pick up the immigration in 2020, is going to equal, and we're going to find that particular bit of data in the dataset.

So if we click that, that should appear in the pop-up already.

You can see it's appeared just there.

Now, it'd be also nice to add a visual cue to the pop-up.

So once again, we're going to add content.

And this time, we're going to add image.

And it's looking for the URL relevant image.

We don't need to worry about these other panels here.

And if we click here, we can find one of the images, which will be the flag of the country.

So if we click that, that starts to display in the pop-ups.

So if we click the other pop-ups, we can see they should be showing the flags of all the countries concerned in the top 10.

We can zoom in and take a look at them in a little bit more detail as well.

Yep, we've got all of the flags appearing there together with the number of migrants that we can see from each country.

So that's a very good visualisation.

So one last thing we can try, because these lines are a little bit pale against this base map, is change the base map.

So we're gonna just zoom in a little bit there, change the base map to dark grey canvas, which will show them up really well.

Let's just shut down our panels so we can see what the map looks like.

I think probably we'll have the legend on as well.

So we can see we've got a very effective visualisation showing quite clearly which countries are in the top 10 and which countries supply more migrants than others.

So we can click on the popups and get visualisations like that.

Very soon, you'll have the opportunity to configure desire lines for migration using GIS yourself.

But let's just check-up on some points from the video demonstration.

Firstly, when using Map Viewer Analysis Tools to create desire lines, in which section do we find the Calculate Travel Cost tool? You may also pause the video here and restart it when you've selected your answer.

Well done if you selected use proximity.

Here's our second check.

What name is used for straight line routes which appear curved because they account for the Earth's curvature? So you maybe also pause the video again here and restart it when you've selected your answer.

In this case, the correct choice is great circles.

Well done if you remember that.

Now, let's look at the task which are gonna help you to configure desire lines for migration using GIS.

As for the task in learning cycle one, you'll need to access the same ready-made webmap called Migration_2.

And the link is there in case you don't have it open already.

In task one, you're going to configure GIS desire lines to visualise migration proportionally.

In task two, you are then going to configure pop-ups for those desire lines.

And finally, for task three, reflect on how effectively desire lines visualise immigration.

So pause the video now to take some time to undertake those tasks.

And when you're ready, press Play again to obtain some feedback.

And we'll see you on the other side of the tasks.

Hopefully, the task went well for you.

For task one, your desire lines to visualise migration proportionally should have looked something like this.

For task two, the popups for your desire lines should have looked something like this, visualising the source country name, its immigration numbers and its national flag.

For task three, how effectively do desire lines visualise immigration? Well, Alex found that desire lines are useful to show great circle routes from source countries and their locations relative to the destination country, but they can become cluttered.

Following on from that, Aisha like using filters therefore, because they help to declutter the desire lines, to provide a focus on the main source countries.

And the colours that we use can be useful for identifying each source country.

Similarly, Sofia quite liked the proportional desire lines because they help to compare immigration from source countries and pop-ups can visualise details such as source country name, immigration numbers, and national flags.

If your answers were very different or you recognise some errors, then please have another look at the video demonstration to check the procedures and check the steps in case you made any mistakes.

Great efforts.

What we've been doing in this lesson is learning about how we can use some GIS skills for desire lines, and they can be applied in many other ways to other sorts of spatial data.

Let's summarise our learning in this lesson with these key points.

Desire lines can be created using GIS to visualise migration, and the desire lines themselves are displayed as great circles.

Filters can be a very useful tool to help us to declutter a map, especially if it shows a lot of desire lines.

GIS desire lines can be configured to visualise migration proportionally to show the relative amounts of migration flows.

And GIS desire lines can also be configured to improve the visualisation, for example, to show source country name, immigration numbers, and national flags.

So in this lesson, we've learned about various powerful ways that GIS can help us to understand migration.

Excellent work.

Hopefully this has been useful and interesting learning for you, and I look forward to joining you again in another lesson.

So all the best and bye for now.