so what exactly is GIS
well it's an acronym and it stands for
geographic information system or systems
but that's not entirely helpful by
itself so let's expand on that
it's an organized collection of Hardware
data software and Personnel that's the
system part
designed to effectively capture store
update manipulate analyze and display
data or information
related to locations on the Earth's
surface that's the geographic part
so when taken together it's essentially
a combination of different elements that
work together to map out spatial data
spatial being the key word there
and much of this spatial data this
geographically referenced information
contains what we call coordinate
information and we'll come back to that
in just a minute
so what can it do what ngis actually do
you may have heard the phrase a picture
is worth a thousand words well this is
the tool this is the field that really
captures that phrase it tells stories
that's what it does and it does it
really well
it does that and people in the field do
that by collecting data piecing it
together and eventually producing a map
infographic maybe some other
visualization to help explain a pattern
of some type
so how does it do that how does JS help
to tell these stories
I mentioned coordinates a little bit ago
now many of you probably remember
learning about your X Y coordinates when
you were younger and still make graphs
with those in mind
the Earth is no different we have an X
or longitude as our horizontal plane and
Y or what we call our latitude for a
vertical plane
we use those to map where everything is
on the globe
knowing two objects coordinates we can
map the distance between the two as a
line and with more points we can build
more complex shapes which we'll learn
about very soon
now in the interest of time we have to
speed through this complicated yet
really cool subject
the key takeaway though is that the
Earth is not flat believe me if it was
my job would be a lot easier
instead it's closer to a 3D oval shape
because it's been spinning for billions
of years and we have to flatten it out
to look at it on paper and on our
computer screens
there are different ways for us to
flatten out the Earth through what we
call projections
however it's impossible to flatten the
Earth without distorting it somehow if
you've ever tried to flatten a soccer
ball you run into the same thing where
something gets stretched or bent or
squished
when GIS folks like myself do that to
the Earth it's part of our job to keep
track of what is getting distorted and
how that affects our map and our
analyzes in the future
but it's important to take away is that
you can be sitting right where you are
right now and with different projections
your coordinates on the earth be
slightly different or maybe even very
different
our GIS software helps us keep track of
this Distortion and map out all this
spatial data remember that keyword
now there are two main directions for
GIS software the first is desktop
software which can do a lot more heavy
lifting but requires extra computing
power and is not as easy to share
information with
the second is web-based software which
while not as powerful still has a lot of
applications most importantly it's
incredibly easy to share your data and
maps with people around the world
and these paths whether desktop or
web-based can be used to study Trends
and do really complex analyzes
so what kind of data can we use to tell
these stories in GIS
now there are two main types of data
that we use in GIS world we call them
Vector data and raster data
the first type of data we will engage
with is called Vector data and is
essentially defined as data made with
points lines and polygons
now I mentioned before how coordinate
points can be connected to make lines as
well as how when we keep adding and
connecting more points we make more
complex shapes
if those lines come back to where they
started to make a complete shape we have
a polygon with an area
let's break it down with an example
your friend is flying out and you want
to take them to the White House
you pull out your phone and open your
mapping application
the phone shows up as a blue dot to show
where you are a point
how are you going to get to the White
House though will you drive will you
take the metro Lee bite
all these are different examples of
wines we have roads we have Metro lines
we have bike paths
think about where you will be when you
travel there too
first you will be in Fairfax County and
then Arlington County and then in
Washington DC
you will also be crossing over from the
state of Virginia to Washington DC
these jurisdictions are examples of
polygons
even building Footprints are usually
polygons even though your phone just
gives you a point to make it easier for
you to understand where it is
all of these are examples of vector data
rasters are another powerful means of
keeping spatial data think of a picture
on your phone for on your computer
monitor
each pixel on the screen has a color
assigned to it and the organization of
these pixels display the image in a way
you can interpret and understand rather
than a bunch of random static
this is how raster data is formatted
it's broken down into gridded cells to
capture data that doesn't really have a
boundary but what we call continuous
data
temperature is a good example of what
raster data is used for
imagine if you went out onto a football
field and measured the temperature at
every yard what would the temperature be
at the one yard line for the second yard
line or the 10th or the 50th
would be the same
probably not it would have ups and downs
As you move across the field because the
temperature is continuous and hard to
capture with a point line or polygon
we use raster data for examples like
this because it's better equipped to
handle it than Vector data
and since satellite and aerial
photographs are pixelated already they
are suited for whatever raster data can
be used for
now we've already covered some GIS
terminology for example I talked about
raster and Vector data projections and
coordinates
but there's a few other words I want to
share with you because it really gets
something pivotal about GIS and what
makes it so powerful
remember my example about traveling to
the White House
I mentioned roads bike paths the
boundary between Washington DC and
Virginia and drone coordinates
also remember I mentioned satellite
images and aerial photographs
each of these are what we call data
layers but why do we use the word layer
because we stack them on top of each
other to display data
if you're familiar with Adobe Photoshop
or Microsoft PowerPoint then you may be
familiar with layering things so that
they display first versus being in the
back
when we work with spatial data in GIS
software we think of it much in the same
way where layers on top are seen over
layers that are beneath them
one thing to note though is that each
layer can hold only one type of data
I can't have two pictures on one sheet
of paper and see both clearly right
the next word that's important to share
with you is what we call features all
the individual points lines and polygons
we have in our Vector data layer is a
feature in and of itself
if you had a spreadsheet this is the row
in the spreadsheet
each Street each address each park each
building are all examples of rows in our
spreadsheet they are all features
compare that to attribute attributes are
the facts associated with each feature
they're the columns in our spreadsheet
if you're sitting in a building that
building has a street number that
combines the street name and Street type
it's also in a city as well as a state
and a zip code which together form one
complete address
even more it was built in a specific
year and maybe one story or a dozen
all these are different details that
might have to do with that one
particular feature they're all
attributes
when we put these together we get what's
called an attribute table that's our
vocabulary word for a spreadsheet
where rows are called features and
columns are called attributes
but why are we talking about tables when
we're mapping people
well it's because an attribute table is
connected to our Vector data sets so if
I were to click on a particular Park in
our Parks layer I would see this table
showing me all the attributes having to
do with that part feature like the name
what supervisor District it's in the
type of part that it is and estimated
acreage
this is really the connection between
the words spatial and data the attribute
table is the data and the spatial aspect
is how it's connected to a map
so why GIS why tell these stories in the
first place
well it's to answer questions and make
better decisions
having more information at hand allows
you to answer deeper questions and make
more confident choices
and let me tell you there are so many
uses for GIS it is absolutely
mind-blowing just consider how many
questions involve where where is there
traffic on the way to school or work
where is crime happening where's the
nearest hospital where are rivers facing
the most pollution where should we put
resources for the incoming natural
disasters where should I locate my next
business
GIS helped to answer all of these
questions and more
there are a thousand applications at
least and we only have so much time to
discuss them with you
and we're really lucky Fairfax county is
one of the strongest GIS communities out
there we have so many different agencies
with their own dedicated GIS personnel
and those that don't have their own
personnel
it is the job of the gis division to
help them out and make sure they get the
most up-to-date and advanced analysis to
make the most informed decisions and
ultimately to serve you the public
now I'd like to end by sharing two
examples of GIS to highlight just how
powerful it was and how powerful it's
become
this first example is one of the first
uses of spatial analysis to tell a story
the years 1854 in the Soho neighborhood
of London the United Kingdom and there
was a massive collar outbreak
now these were not uncommon at the time
because germ Theory hadn't been
solidified yet and wouldn't for another
decade or so
some people had hypothesized yes but it
had not gained enough traction yet for
people to become truly receptive to the
idea
instead we operated under something
called the miasma Theory literally
translating from ancient Greek to mean
polluted air
so a physician by the name of Jon Snow
hypothesized something that at the time
was considered rather unorthodox
he thought that water might be the cause
for the spread of Cholera much in the
same way that bad air can spread
sickness essentially if bad air can
exist well why not bat water
snow mapped out where all the deaths
from this outbreak took place along with
the Reverend Henry Whitehead was the
staunch believer in the miasma Theory it
was actually looking to prove snow wrong
that's what all the black lines on the
map to the right are they're tallies of
deaths that each address from this
outbreak
and when you look at where the public
water pumps are overlaid on this map we
can better understand why snow had the
hypothesis that he had
so the two of them scientist and priest
actually found the same information from
inverse audiences
snow found from interviews with victims
families of the victims that all drank
from one single pump the Broad Street
pump
Whitehead found that those who had never
been sick never touched that bump though
taking his findings to the local
governing Council they were given
permission to remove the handle on the
pump the very next day making it
completely unusable
soon after the sickness passed entirely
while the epidemic may have been passing
on its own this certainly was the
deciding factor to end it
this study which eventually was
published helped to earn snow the label
father of epidemiology epidemiology
being the study of disease
yet he may not have done it without some
simple spatial analysis too
even if he had the right assumption he
may very well not have convinced the
governing Council without the simple map
and the great thing about this case
study the truly awesome thing is however
you break it down whether just glancing
at the distribution using sophisticated
GIS software or in-depth spatial
analysis methods the answer always
points to the Broad Street pump
let's look at GIS today
the covid-19 dashboard by the Johns
Hopkins University Center for system
science and engineering is a prime
example of what JIS stands for today
you may very well have seen it or heard
about it before
it is somewhat of a coincidence that
perhaps one of the most popular uses of
GIS today is also an example of
epidemiology in action
where is it public health is one of the
most important things to look after and
is perhaps one of the strongest uses of
GIS
a dashboard is just a type of product
that displays information like the
example on the screen it has statistics
a map and charts that are all connected
to show different sides of the same data
this one has kept track of code cases
deaths and eventually vaccination
distribution in real time for the past
three years from authoritative sources
around the globe 260 sources to be exact
by March 2020 just six weeks after it
was shared publicly it received a
billion visits
since then it's been seen in
presidential addresses and still shows
up in news articles today and has been
visited more than 1.6 trillion times
making it the most popular example of
GIS today by far just think of that for
a minute there is this one site where
any one of you can type in a link and go
see an immense wealth of statistical
data for the entire world for this one
disease that is updated on an hourly
basis
compare the Jon Snow example who acted
with one other person and collected some
data on paper and made an extremely
positive impact
now we have hundreds of authoritative
sources providing timely data to one
source and is readily accessible by
anyone with an internet connection
this is the power of GIS and how far
it's come even still it continues to
grow
I hope you've enjoyed learning some of
the basic building blocks that lead to
this level of cooperation
if you're interested in seeing what more
Fairfax County has to offer in the world
of GIS we encourage you to check out our
homepage at fairfaxcounty.gov Maps
through here you can access our static
map Gallery where with just a few Mouse
clicks you can download wall size maps
of various themes like Parks
Congressional boundaries and Fire and
Rescue assignments
or maybe you'd like to look at our
interactive map gallery to view over 100
different web-based applications to let
you view our Fairfax County Properties
infrastructure historical imagery and
much more
or maybe you want to download that
County data yourself to using your own
geospatial tasks we'll head on over to
our open geospatial data portal to
explore more than 100 different data
layers and tables that we make available
to the public
we make all this available to empower
yourselves for your mapping needs but if
you ever have any questions you can
always reach out to us at our home page
at fairfaxcounty.gov Maps or by phone at
703-324-2712
take care