Hello, in this demonstration we're gonna be focusing on the vector data model and
particularly a few of the different idiosyncrasies of it and
how we might manipulate some of these data.
So before we really get started in ArcMap itself,
I wanna just take a look at the files that you should have downloaded for this week.
So as we talked about in the lecture, each one of these
is part of the shape file, part of the vector file format that we use in ARC GIS.
See you see we have lots and lots different files, all with the same name.
So, what these are is particular pieces of it,
one might be the spatial index, one might be the attribute table,
others might be the actual geometry of those particular features.
So, once we've looked at these a little bit, let's go ahead and
see what they look like in ARC GIS.
So if you start up ARC GIS just like you have in the preceding demonstrations
you wanna go ahead and choose blank map.
So you're gonna double click on blank map.
This will bring it up the same way we've seen before where we have our layers,
we have our display area.
And the way that we're actually gonna add data in again,
is to use this tool right here.
This little sort of square diamond with a plus on it, so chose that,
and then what we wanna do is navigate our way to the place
on the hard drive where we've stored those data.
So mine I've already made the connection to that particular folder, but
if you need to do this again you're gonna use this button to sort
of map the location of the folder that you want to go to.
So I have mine hidden on my N drive in the GIS folder, so let's choose that.
And then you should have downloaded and
saved the lab or demo three data.
So if we look in here, you see that instead of lots and
lots of different parts of the same file.
We just see the one individual layer itself.
And, in fact, if you look at the little icon it's giving here, so
this green icon means basically that it is factor data.
The software is smart enough to see that it's vector data.
And it's actually showing us that these are points, these are polylines,
and these are.
It's showing us the type of feature as well.
Now you want to go ahead and add in a few of these.
We're gonna work with the entire U.S. data first and
then later on we'll look at these Indiana ones, so all the ones that start with IN.
So we want to go ahead and choose Canada.
Go ahead and hold down control.
And then choose MEXICO, STATES, US CITIES AND US HIGH.
So hit Add, you can do these individually if you want as well.
But what should happen when they've loaded up is that we're going to see
lots of different things showing up in different colors.
Based on just sort of the default,
your colors probably won't look the same as mine.
So we have the provinces of Canada.
The states of Mexico and the states of the U.S. are all polygons.
You can see that in the little square of colors here, rectangle of colors.
We have U.S. highways which we poly-line data here and
then we have UFCs, so locations of populated places.
Now I hope you remember the different ways you can zoom in and out on the layer,
let's go ahead and do that a little bit lets just zoom in,
I'm using my mouse wheel to do it, you can also do it with this tool here.
Let's just zoom in an you can see as I zoom in and
out the scale stays the same the size of those points doesn't change.
The width of the lines, the width of the edges around a polygon.
They don't change at all.
If I move these things around in the Table of Contents,
this is the order that they're being displayed, so if for
some reason I wanted to take the US cities and put it below the states,
I can't see them anymore, because my states are sort of on top of them.
The layer is still there but I can't see it.
So you wanna always be sure your points are on top
of poly lines on top of polygons.
And you can turn them on and off over here as well, so you're not removing the layer,
but you're just not letting it be displayed.
So if we zoom out a little bit,
again remember we can always hit this button to go back to our full extent.
And we talked in the lecture about how it’s important an important
part of GIS system in particular of vector data.
Is that they have an attribute table associated, and
that's exactly what we want to look now is what the attribute data
with each one of these particular shape files is.
Now there are two different ways we can do this.
We can look at the whole table itself or we can look at the record for
an individual feature.
So if we wanted to just look at an individual feature we could use
this identify tool, sort of a blue circle with a white eye in it.
That'll switch our icon to be something that looks like that.
And then I can click on a feature, and
it's gonna give me a little pop up that shows me what that feature is.
In this case I have hit British Columbia, one of the Providences of Canada, and
if I wanted to I could change what I'm being identified in.
In this case it's only gonna show me the top most layer, but
I can change it to show me all layers, one particular layer, pretty much anything.
This is important because if had tried to hit something down here,
well it's not going to be able to figure out what city I hit because I'm zoomed so
far out and they're sort of overlaying each other.
So its showing me all of those cities that I may have hit,
most of which are in Pennsylvania.
So you can see there is a lot of data with those as well.
Now you can zoom in and out and sort of.
Play with this identify tool.
It's a good quick way to find out what you're actually looking at so Missouri there.
or miss, I guess I had accidentally switched it to only being identifying US cities, so
I'm gonna switch it back to top most layer.
And then I can hit pretty much anything I want and it'll identify it for me.
Now, if I want to look at the whole attribute table,
I'm just gonna right click on it here in the Table of Contents.
Go down to Open Attribute Table.
Now I can see that, for those cities, I have a lot of information in there.
Have the name of the city, have the state that the city is in, whether or
not that city is the capitol, its population in 1990, the number of
households, a little bit of census data on ethnicity and gender in here as well.
Now I can look at some of the other ones as well.
If I look at the U.S. highways,I have things like what type of road it is
the administrative class, is it an interstate or state highway and
then I have the name as well for most of them and states are pretty much the same.
I look at Canada you can see I just have the name for it.
So I'm gonna close out of my attribute table.
You can dock this wherever you want.
And I'm just gonna go ahead and close mine down.
So we may want to begin to change how these are being displayed as well.
One of the neat things about having attribute data is that we can change
how the layer is being displayed based on, so I'm just gonna turn off my highways and
my cities cuz they're kind of in the way.
And I'm actually gonna turn off Canada and
Mexico cuz we're just gonna look at the US.
And let's go ahead and try to zoom out to see the entirety of the US.
And we do that by right clicking on States, choosing zoom to layer.
This is a thing you're probably gonna do pretty regularly,
just to do the zoom to layer.
I wanna change this so it's not just displaying every single with this purple
color, if I wanna change it to be something else,
I'm gonna do that in the properties for this layer.
So just like we did with raster data,
if I either double-click quickly on states or right-click and
go to properties in my table of contents, I can go over to my symbology tab.
And I have a bunch of different ways that I can display those data.
So if I just wanted to just do categories here,
It's gonna ask me what value field I wanna use.
Well, I'm gonna go ahead and use the state name.
Then you see, nothing happens until I hit add all values.
What this is gonna do, is it's gonna populate it.
Probably, possibly with a different color ramp than what you're seeing.
It usually defaults to this kind of pastel one.
And it's gonna display each value differently.
So if I hit okay, you can see that now in my table of contents it's showing me what
those colors correspond to, so this sort of dark purple is Alaska.
This sort of lighter green is Alabama and
as you sort of move down you see all the different colors.
Some of them probably come pretty close to repeating.
That's okay, but just know that it's displaying them all individually
based on a single feature like that.
Now I can also label these pretty easily.
Again in the layer properties here.
If I go over to labels.
Well the first thing I want to do is turn on label features and
then if I wanted to label it by the state name I would just leave it as is.
It's gonna ask me what field I want to use.
So let's go ahead and hit ok.
And it will label them,
and as I zoom in and out those labels will stay the same size.
So in some cases that works really well if I'm zoomed in, and
if I'm zoomed out very far, it doesn't really help me very much.
It's pretty hard to see what is being labeled as New Hampshire over here.
So, I might want to switch, change this so that instead of labeling based on my state
name, I just double-clicked again on my states in the Table of Contents here.
I may want to do it where I'm just using the abbreviation.
So these are postal abbreviations for the US states.
And that works a little bit better if I'm zoomed out like this.
Then I can also do things like measuring distances pretty easily.
I have another little tool up here that'll allow me to measure distance.
So if i click on that I could say measure the width of Utah and
it's going to snap to the edges, as I drag it across here it's going to tell me
that's somewhere around 437 thousand meters across the entirety of it.
Now in some cases with some layers you might up getting something that says
degrees here, or decimal degrees.
That's not really a linear measurement so
in that case you'd want to change it somewhere in this units up here.
So this little drop down you can change it to give you kilometers,
pretty much anything else.
You can also do areas,
you can measure pretty much anything with the measure tool.
It doesn't save it anywhere so you'd want to actually go ahead and add it in,
write it down or something like that.
Now, I have a few other things that we can do as far as changing how we're
displaying particular types of features.
So, for states each one is individual each feature is it's own thing, and
has it's own name and should be displayed differently.
But, if we wanted to look at something again, like our highways here,
if we turn that layer back on,
if you remember the attribute table there has a different administrative classes.
So what we have are several different types of data.
Several different categories.
So we might want to display these differently.
So, I 'm just closing down my attribute table.
I'm going to go in here and what I want to do is back in my symbology.
I'm going to change it to categories and I'm going to do administrative cost.
So now when I hit all in all values, well, it's going to display,
there's only three different things in there: there's interstates,
there's state highways, and there's US highways.
So if I want to change these things so I can see them a little more clearly,
the difference is I can just click on that feature, sort of symbol here.
Say I might wanna do highway for this one.
For state highway I might wanna do major road, and for US highway,
I might wanna do expressway.
So now I have different types of ways to display.
I have a difference in symbology for each one.
So when I hit okay now,
you see that almost everything that we have are interstates.
There's a few U.S. highways sort of heading up into Canada.
And then the only place we really have state highways left in this
particular data set is in Alaska.
So what we have, is we've done the same sort of displaying,
the same sort of symbology changing, but we've just done it in a way that it's
showing us the different categories.
So we can also change things based on numeric values, so if we remember,
I'm gonna turn off highways here.
Remember we have cities.
If we open this up, we have a lot of numeric values.
So we may want to change this to show the symbol itself is bigger or smaller or
a different color based on the population field.
So to do this, we're going to go back into symbology.
In this case we're going to go down away from categories into quantities here.
So it's going to ask us what the value is, let's do population 1990,
we're going to leave it on graduated colors.
And what's going to happen is the lower values are going
to be sort of lighter colors, the higher values are going to be darker values.
So if we zoom in a little bit, you can see that there’s a lot of places that have
relatively low populations, and then just a few that have higher populations.
So like New York here is often one of the really big ones.
Washington D.C. should be somewhere in-between.
Now we can also do this by, if we go into our symbology.
Again, that was graduated colors.
We could also use graduated symbols.
What that's going to do is just make a bigger symbol.
But in this case, let's just go ahead and change it so
that our number of classes is ten instead of five.
If we wanted to change the color as well.
Make this say, start with a nice light red,
we can do that in the template there.
So now you can see that the bigger ones are showing up or some cities are bigger
than others and that they're being sort of displayed in this very intuitive way.
Where they're a bigger symbol than the smaller ones.
Again if I zoom out they're not gonna change,
their size is gonna stay the same on the screen.
So eventually I'll start losing the ability to really see what's happening.
The smaller ones are sorta overlain by bigger ones and
everything's lost in the overlapping.
Now, if I wanted to display multiple different values, say, for
instance, I have things that add up to 100%, like number of males and
number of females, or any of ethics, the ethnic identifications over here.
I can also do that.
So if I go in to the most complicated one here in my symbology tab,
for a numeric value or charts, what I might want to do here is create
a little chart that is males versus females, percentage wise.
What you'll immediately see is that it makes a huge mess at this scale, so
you'll probably want to zoom in quite a bit.
Then I want to just tweak it a little bit so I'm gonna go ahead and
turn off the prevent chart overlap.
I'm going to hit the size tab, your button here, and
I'm just going to crank this down to being around 12 or so.
Just so that they're much, much smaller.
And then I'm going to hit OK.
So now what I see is that for each individual place, it's displaying it
in a way that's showing me Some comparison of two different values.
In this case, the number of males to the number of females.
So let's say at this point I had made this really really neat thing,
where I wanted to save everything.
I wanted to save how it was being displayed.
I can do that by right clicking here and going down to Save as Layer File.
And what this layer file is, is it's not the actual data.
All it is is how the data are being displayed.
So I can load this back up and it's a link to that file how it's being displayed,
so I can reload this in another map document.
I could reload it in the same one if I had accidentally removed it.
It's a good way to save your symbology without having to make
a different copy of the data itself.
Now let's look at one last little thing and that's selections.
And we talked about this in the lecture for this module about how the selections
are actually pretty important part of what GIS data will allow you to do.
Now, I'm just gonna go ahead and
change my symbology here to be back to a regular symbol.
Just for ease of display.
I'm gonna do the same thing, well, I'll leave highways as is.
So let's look at a couple of different ways we might select data.
The first thing we can do is selecting by attribute table data, itself.
So if I open up this attribute table for U.S. cities and say I wanted to select
all of the cities with a population of greater than say two million or something.
I could hit this Select By Attributes button right here so
I just to repeat that it's this one right here.
Once I hit that I'm sort of creating a little equation that's gonna let me select
it based on something that I've put in.
So if I wanted to go through and say my population is greater than,
actually we’ll do 20,000.
2020.
And hit Apply.
It's gonna select all the ones both in the table itself,
so that's 1,655 out of the 3,000 or so cities.
And then if I close down all these other windows and
kind of zoom my way back out you'll see it selected all of them.
Again if I'm zoomed out all the way it doesn't make a lot of sense, but
you can see sort of the difference between small and big ones.
We can also do things like, excuse me.
I'm gonna open the attribute table, go back into select the attributes.
And I can do places where there are more, where
there are fewer females than males, simply by building an equation like this.
It's a really good idea to build the buttons,
build the equation using the buttons.
This is what's called an SQL or Standard Query Language.
It's relatively sensitive.
So try to use the buttons to build your theme.
So this is gonna give me all the cities.
There's not a tremendous amount of them.
Where there's a higher male population than female population based on
the 1990 census.
Now we can also do selections based on location.
So in this case what I'm gonna do first is I'm gonna clear my selection.
I'm gonna press this button just to clear out the selected features.
It's also found up here on the main window.
And say I wanted to find all of the cities, that are within or
pretty close to a major highway.
Well I can do that in my Selection tab on the main window here.
Select By Location.
And I'm just building an equation here.
I'm gonna build, I wanna select features from US cities.
That, are somehow related to the source layer, or highways.
And I wanted to do within a distance but
I want that distance to be, we'll say 20 kilometers.
So every city, that’s within 20 kilometers of a major highway.
So if I do that, it's now selected all of those for me.
So if you see anything that is a little bit further away from one of these roads
has not been selected.
Now there are lots of different ones I can do here.
I can very easily do cities that fall within Iowa or within Missouri.
And the way I have to do this is by sort of staggering them together.
So I might wanna use tool here where I'm actually just able to just
select something by clicking on it.
To select Missouri Now, I can do that Select By Location.
So US cities that are within states.
And I wanna make sure I turn on use selected features.
So it's only gonna use that one particular feature.
And then this is a case where I'm going to use intersect the source feature.
Turn off distance.
So what it's gonna do is it's gonna select all of the cities that
fall within that one selected state.
And there you go.
If I zoom in you can see that things that even though they're right around the edge,
it's still has missed them.
So, it's selected only those ones that fall within that particular state.
So, that's how you would string together multiple selections.
That's a very powerful part of the GIS software packages,
is the ability to sort of string these things together in a useful way.
And part of the assignment for this module involves doing some of these selections.
I encourage you to play around with some of the other ones that are in here.
They're listed in the lecture, and
they're listed in the demo notes in a little more detail as well.