Day2 Session2 Exploring GIS

8/11/2019 Day2 Session2 Exploring GIS

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M. D. Nowbuth UoM November 2011 Page1

UNIVERSITY OF MAURITIUS

FACULTY OF ENGINEERING

CIVIL ENGINEERING DEPARTMENT

Exploring ArcGIS

LEARNING OUTCOMES

At the end of this session you will have learnt about:

1. How to connect to a Folder

2. The structure of a Shapefile

3. How to changes the display properties of a layer

4.

How to create a report from the digital maps5. A Coverage and a Geodatabase.

1.0 CONNECT TO FOLDER

The data that you will need in this working session is located in the Folder

IGIS1. From ArcCatalog first Connect to Folder IGIS1. Note the different

folders present within IGIS1 [Map Documents, Maplewood, Redlands, Regis,

World, National & Subdivision].

2.0 OPEN A SHAPEFILE


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A shapefile is a thematic layer, i.e, it can contain only one type of feature

lines, polygons or points.

Browse through the folder Maplewood, you will note the following files:

[floodcov, homeshp, photoclip]. Observe the description of each file in theright hand column. You will note that homeshp is a shapefile.

You will now open ArcMap from the ArcCatalog screen . When ArcMap is

open, you will find a folder named LAYERS in the left hand column. Right click

on this folder and a set of commands will appear. Select the command ADD

DATA.


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Browse through the folder Maplewood and select homeshp. A plan view of

buildings will appear on the ArcMap screen. You may use the following buttons

to adjust the size and position of the map .

This homeshp file is made up of polygons, the feature polygon has been used to

create this shapefile.


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2.1 OPEN ATTRIBUTE TABLE

You will now open the attribute table associated with the homeshp shape file.

Bring your cursor in the left hand column and right click on the file homeshp.

You will notice a list of commands, from which OPEN ATTRIBUTE TABLE.

Select this particular command. A table will appear, showing attributes

associated with each polygon.

How many housing units are there (polygons)?........................................................[145]

Which polygon has the highest and the lowest area?..................................[99 & 109]

How many buildings does the company Sams Service owe?.....................................[5]

2.2 QUERY 1 - WHERE IS A PARTICULAR BUIDLING?

Suppose you need to identify the most costly building from this digital map.

The first step is to use the SORT command and identify the most costly

building (Attribute VALUE). The next step will be to click on the left hand

corner of the attribute table and highlight the entire row (ROW 139). The row

will be highlighted and at the same time the building will also be highlighted.

Move the table to observe the highlighted building.


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Similarly you can highlight the building which has the largest perimeter or the

smallest area.

You can also highlight a series of buildings of your own choice by pressing the

keyboard button CONTROL.

2.3 CALCULATE DISTANCE

Look for the following button . This is a ruler with which you will

measure some distances. As a first trial you will click on this ruler and measure


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the perimeter of a particular building. Compare this value with the actual

perimeter as is recorded in the table of attributes.

First use the identify button . Having selected this button, next click on

the building for which you intend to measure the perimeter. When you click on

the building all the attributes linked to this building will be listed.

Note the recorded perimeter of the building. Next use the Ruler to measure

each side of the building and hence calculate the perimeter. Compare the

perimeter value obtained with the recorded one. There will likely be some

differences, this is due to the fact that at times it is difficult to select the

actual vertex of the building. To help a user, the command SNAPPING is

available. Activate the command SNAPPING and remeasure the perimeter.

This time the value is more accurate, just like what is recorded in the attribute

table.

2.4 QUERY 2 You will now calculate the distance from the company Sams

Service and identify which of the two sister companies are located closest

to each other.

The first step will be to identify all the sister companies.

Open the attribute table and carry out a sorting, to group all the Sams

Service buildings.


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Next step, then use the keyboard control button, to highlight all the

sister companies.

The second step will then be to use the DISTANCE command to find the

distance from the centre point of each building to the next sister company.

From there you will be able to identify which two sister companies are located

closest to each other. (Remember to activate the SNAPPING command).

Select the top left hand corner of each building for consistency.

The two closest buildings are those with FID number 32 and 52.

3.0 CHANGE THE DISPLAY

You will now learn how to change the way the buildings are being displayed. You

may wish to change the colour of the building, the outline of the building and

the attribute that it represents.

Step 1: You will change the colour of the buildings to green.

Right click on the file homeshp, and select the command PROPERTIES. Or

you can just click on the symbol representing the homeshp file in the left

hand column. A set of colours will appear. Select any other colour and

click on the button OK to accept the change, and note the change.


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Step 2 You will also change the outline of each polygon

You will notice on the right hand side the Outline colour and width option,

change it to a different colour RED and a different thickness from 0.4 to

2 and observe the change.


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Step 3 Now you will put some labels to each building

Right click on the layer homeshp on the left hand column. Select the

PROPERTIES command and from there a sub menu will appear. Click on

the LABEL LAYER IN THIS FEATURE and click on the commandPLACEMENT PROPERTIES in order to format the labels.

Step 4 You may also change the attribute that the building displays

visually, for example VALUE of the building.


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Each polygon has several attributes associated with it, as illustrated in

the Attribute Table. You will now display the layer homeshp based on at

least 2 different attributes. Right click on the layer homeshp in the left

hand column box, and select command

PROPERTIES/SYMBOLOGY/QUANTITIES/Graduated Colours.

You will then select the attribute VALUE. Click on the button OK to

accept the changes. Observe that different colours have been used for

given ranges of the value of the buildings.

You may now explore this command and change the display to view the buildings

as per the attribute CLASS.


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4.0 CREATE A DIGITAL MAP FOR A REPORT

You will now create a digital map that can be used in a report, inserting the

north arrow, the legend, the scale and a frame. In order to format a map before

printing it or before putting it in a report you will need to change the displayfrom DATA VIEW to LAYOUT VIEW.

Once this is done then click on the command INSERT in order to add the

various elements you would consider important for a proper display of the file ina report, such as the North Arrow, the Scale, the Legend, the Title and a

Frame. This file can then be exported as a bmp file to be inserted later in a

report.


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5.0 DISPLAY TRANSPARENT LAYER

You will now open a coverage file. Browse through the folder Mapplewood and

open the coverage floodcov. Right click on this file and select

PROPERTIES/DISPLAY and make it 50% transparent. Then add another layer,Photoclip and observe the transparent effect.

6.0 GEODATABASE

You will now open a Geodatabase, NATIONAL.mdb located in the IGIS1 folder.

When you open the geodatabase, a series of layers will appear, and you can

select to open any two of them.


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7.0 CREATE A BUFFER ZONE

You will now learn how to create a buffer zone around a feature of interest. The

first step will be to select the feature and once the feature is selected only

then you will be able to create a buffer zone.

Step 1 Select the feature of interest

Go to the main menu and click on the submenu SELECTION. Now chose SELECT

BY ATTRIBUTE. You will now chose attribute OWNER and the owner will be

MARTIN SHIPPERS. The chosen building will be highlighted.

Step 2 Create a buffer zone of 50m around the building of Mr. Martin

Shippers.

Go to the main menu and click on the submenu GEOPROCESSING. Activate the

command BUFFER and chose to create a buffer of 50m. Given that you have

selected the house of Mr. Martin Shippers the buffer zone will automatically be

created around this house.

8.0 CREATE A BOOKMARK


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A bookmark is an information of interest. Suppose you want to highlight the

buffer zone around the house of Mr. Martin Shippers. You can zoom to this

zone and then create a bookmark. This will be stored as a key information that

you may retrieve later while working.

Step 1 Zoom to the point of interest

Use the zoom buttons and zoom to the buffer zone.

Step 2 Create the bookmark

Once you have zoomed to the buffer zone, create a bookmark give it the name

of Martin Shippers_bookmark. You can now zoom back and continue your work.

At a later stage if you wish to view the zoomed area again then all you have to

do is to to back to the bookmark and select Martin Shippers_bookmark.


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9.0 OVERLAYS

Overlays are key analytical processes in any GIS environment. ArcGIS offers

several possibilities of overlay techniques, and you will use two of them here,

union and intersection.

Step 1 When in ArcMap open the geodatabase NATIONAL

Add all the layers present in the National geodatabase [Capitals, Roads, States,

Counties, State_names]. Activate the ArcTool box by clicking on this button

. A drop down menu will appear and select the analysis tool box, you will

notice the following commands will appear [Extract, Overlay, Proximity &Statistics], select the command OVERLAY/ Intersect.

Step 2 Choose to overlay the following two layers Counties and Roads, using

the Overlay/Intersect command. The result should be the common features in

both layers.


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10.0 QUERY BY LOCATION

In this step you will query a database based upon your location. Go to the folder

REDLANDS, and insert the following layers Donut and Railroadcov. You will

select all the Railroad classified as SP RAILROAD which are located within abuffer of 5000m of the donut shops. You will then repeat the same exercise

to select the SP RAILROAD which are located within 100m from the donut

shops.

Step 1 First you will need to select the Railroad which are classified as SP

RAILROAD, using the SELECTION>BY ATTRIBUTES. Note that there are 2 SP

RAILROADS.

Step 2 Next step you will select only those SP RAILROAD which are located

first within 5000m from donut shops and then within 100m from the donut

shops. In the first instance (buffer zone 5000m) all the three SP RAILROAD

are retained and in the second instance (buffer zone 100m) only one is retained.

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