Manual to basic gis

Manual to Basic GIS – Sushmita Timilsina Page 1

Manual to

Basic GIS

Prepared by: Sushmita Timilsina


Contents:

1. Introduction

2. Playing with data

3. Projection system

4. Georeferencing

5. Data analysis

6. Importing and exporting data in and out of GIS

7. Data layout


INTRODUCTION

Arc GIS when installed it automatically the following with itself

1. Arc catalogue

2. Arc map

3. Arc Globe

4. Arc Scene

Component: 1. arc catalogue

a. Data loading and preview with their information about data and metadata

-Difference in vector and raster file

Data can be easily loaded onto the Arc Catalogue by browsing our

destination folder that contains our data. Data may be raster or vector.

The differences can be seen by previewing the graphics as well as the

properties of the data. The data can be viewed through Preview option

just above the file. The attributes information is also available. The

attributes can be spatial and other metadata information.

b. Creation of files(shape file, xml)

The databases and required files can be created in our destination folder.

To create File Geodatabase, personal geodatabase, shape file, xml, tables

etc. it is as simple as making a new folder. Just you need right click on

the free space and click on what you want to create.

For creating a shape file:

Right click on the free space inside the destination folder or in the

destination folder and choose New and select Shapefile. A new dialogue

box will pop up that contains the information to be filled up to create any

shape file.


You must give a name to the shape file. Choose the feature type you

want to make your shape file (point, line, polygon etc). Now provide the

Spatial reference System to the file through the click on Edit. You can

then select, import or create your new projection that is necessary for

our project. Selecting select you can select the predefined spatial

reference system necessary for your project. Selecting import you can

simply import the system that has already been used also you create your

own using create. Once you provide these information your shapefile is

now created.

2. Arc map

a. Create your own interface by adding, removing and managing the function

that is necessary for your analysis. You can add your necessary function by

customizing the extension of simply through right click on the top free space

and check in in the necessary functions.


3. Arc toolbox

Number of tool is present in Arc GIS inside Arc Toolbox that help in analysis.

There are many tools inside the toolset. Just go on browsing it and explore. You

can also create your own toolbox. To do so just right click on the free space and

select new to create new and select add to add existing toolbox.

Playing with data

Add your data using add button displayed as plus button found above in the

task bar. You can add raster, vector or database file in Arc map. The layer can

be displayed to see what it depicts. In order to change the appearances of the file

you add explore by right click on the layer. Now you see copy (copies the

layer), remove (removes the layer), open attribute table (opens the attribute

table), zoom to layer (zooms the layer to be wholly visualize within the layer),

selection (for selecting the feature or any criteria) data (with data you can

simply export a single layer from Arc GIS or make the layer permanent and also

view its metadata).

The main important and mostly used option in the right click is the Properties

option. When the properties is selected it opens a window like following.


Each tab is equally important in layer properties:

General: in general you can change the layer name, can make it visible, add

description and aslo manage scale range.

Source: you can see the extent of your data. The current data source of the layer

can be seen. Also if you want to change the spatial reference system you can do

it by selecting Set Data Source.

Selection: selection symbol to customize our selected features. You can change

the symbol or colour for your selection.

Display: this tab maintains the displaying information. Transparency can be

adjusted using this tab.

Symbology: this is the most used tab. You can give the symbol of your interest

for single and multiple features. On the left side, under Show: has Features that

contains single symbol inside which can be assigned to the layer. Similarly,

Categories contains unique values (you assign unique value and colour to

different feature of that layer) unique values, many field (you can assign unique

values to multiple field) match to symbol in a style (to match the symbol with

the predefined style in your directories). Under the Quantities you can find

Graduated colors (provides colour graduation to field using the value of the

field) Graduated symbols (provides the symbol graduation for the field with the

values) proportional symbols (it draws the quantities using symbol size to show

exact values). Under Charts you can draw pie chart, bar/column or stacked

chart for each feature. Under multiple attribute it contains Quantity by

category (useful to draw quantities for each category).

Fields: it displays the field of the layer. You can choose the field to be visible

and see, select or clear the layer’s fields.

Definition Query: this tab is to define the query. Query Builder can be used in

order to build query of our on using the functions defined.

Labels: this tab is used to label the features in the selected layer. The text

symbol, colour, size , scale range, placement properties and label style can be

managed in this tab.

Join & Relate: Join joins the two layers attribute table with a common field in

both the table. Relate associates the table /layer with one another.


HTML Popup: to show content for the selected layer.

Now explore the Attribute table. You see rows and column like in the simple

table. Rows are called tuples or record. Columns are called fields. Fields can

be added or deleted. The simple geometry can also be calculated and statistical

data can be observed. Once you select on any tuple the selection will also be in

the display. Explore option on the right-down side.

Projection

Projection is necessary to represent the data onto the screen. Distortion is

always likely to occur due to projection. Therefore it is crucial act to choose the

type of projection system.

UTM(Universal Traverse Mercator) is the universal projection system that takes

the origin to be the intersection between Greenwich meridian and equator. This

system divides the globe into zones from -180 to 180 each of 6 degree zones.

Nepal consists of two zones 44 and 45.

Nepal lies in the northern hemisphere. The department of survey of Nepal has

defined the MUTM(Modified Universal Traverse Mercator) for Nepal where

MUTM divides the zones of 3 degree each. Nepal consists of three zones 81,

84, 87.It is hence necessary to define the zone of any coordinates to prevent

dilemma.

Data frame properties can be used for viewing and assigning projection system.

Data frame properties is available in the View button of menu bar. Also

projection system can be viewed and set in source in properties with rt. Click in

the layer of our interest.

Also can be defined and transformation can be done if necessary


Geo-referencing

Data is always not provided like we want.. so we must create data

TIC_ID X(Easting/Longitude) Y(Northing/Latitude)

1 574000 3116000

2 577000 3116000

3 577000 3112000

4 574000 3112000

Aligning geographic data to a known coordinate system so it can be viewed,

queried, and analyzed with other geographic data is termed as Georeferencing.

Georeferencing may also involve shifting, rotating, scaling, skewing, and in

some cases warping, rubber sheeting, or orthorectifying the data.

Any image or orthophoto has no spatial reference so to do our analysis using the

existing image, first we need to georeference the image with the known

coordinates. It involves identifying the known points in the image and assigning

the points on the image and rectify it.


After assigning the points calculate RMS error.. if error is permissible rectify

the picture to image and provide its projection system. Also must define the

projection system to data frame and the raster layer. Now you can digitise

(points, line polygon) your data necessary after the creation of any shape file in

the same location using editor.

Data analysis

Spatial Analysis (extract, proximity, clip, intersect)

The Extract toolset contains tools used to select features and attributes in

a feature class or table based on an attribute query (SQL expression) or spatial

extraction. The new features and attributes are stored in a new feature class or

table.


Tool Description

Clip

Extracts those features or portions of features from an input

coverage that overlap with a clip coverage polygon. The Clip tool is

similar to the Intersect tool; however, the Clip tool does not transfer

any attributes from the clip coverage to the output.

Select

Extracts map features from the input coverage based on logical

expressions or applying the criteria contained in a selection file.

Split Clips portions of the input coverage into multiple coverages.


Proximity is another of the most basic GIS questions, such as:

How close is this well to a landfill?

Do any roads pass within 1000 meters of a stream?

What is the distance between two locations?

What is the nearest or farthest feature from something?

What is the distance between each feature in a layer and the features in

another layer?

What is the shortest street network route from some location to another?

Feature-based proximity tools

Feature-based proximity tools Raster-based distance tools

Create Thiessen Polygons creates polygon features that divide the available

space and allocate it to the nearest point feature. The result is similar to the

Euclidean Allocation tool for rasters. Thiessen polygons are sometimes used

instead of interpolation to generalize a set of sample measurements to the areas

closest to them. Thiessen polygons are sometimes also known as Proximal

polygons. They can be thought of as modeling the catchment area for the points,

as the area inside any given polygon is closer to that polygon's point than any

other.

Importing and exporting data in and out of GIS

Mainly used extension is kml that is used by google earth. Using data in ArcGIS

extracting from Google Earth:


Google earth is needed to be installed first into your computer.

Open Google Earth. Now move towards the area of your interest using zoom,

pam, rotator to the area of interest. Now create a new folder where you want

your data to be saved inside the My Places. When the folder is created now you

can start digitising by using add button. The button can be point, polygon or

line feature. When you are done with extracting your necessary feature, now we

move towards using it in the GIS and save it to our destination folder by right

clicking on the folder.

In order import the data directly into GIS you need check in the

interoperability option in extensions. Now you need to browse the data

interoperability tools in Arc Toolbox and select quick import and then you

import your data that you created in Arc GIS. It automatically supports the data

and if you check the spatial reference system, it gives the wgs84 of that of

Google Earth. Now you can move forward for your analysis.

Exporting data to Google Earth

Now when the data you have is necessary to be displayed in global scale, you

can export your layer. Before exporting your data you need to convert your data

to kml. Arc GIS provide tools to convert layer to kml. Automatically it

converts to the file that is easily accepted by Google Earth. When the data is

exported successfully you can easily open the file without opening Google

Earth. When you open your file it automatically opens the Google Earth to the

region that you exported from Arc GIS. Now you can visualise your data.

ENJOY!!


Creating a map layout

A page layout is a collection of map elements organized on a virtual page,

designed for map printing. Common map elements that are arranged in the

layout include one or more data frames (each containing an ordered set of map

layers), a scale bar, north arrow, map title, descriptive text, and a symbol

legend.

Below are the general steps for laying out a map in ArcMap:

1. Before starting in ArcMap, it's wise to design the arrangement of the

elements onto the map page and plan your layout.


2. Start by setting your layout's page size and dimensions. Create, edit, and

symbolize your data as appropriate in your data frame(s).

3. In layout view, click the Insert menu to add elements onto your layout. If

you have more than one data frame in your map, the elements you insert

will relate to the active data frame (to activate a data frame, right-click its

name and choose Activate).

4. When you add map elements (for example, a scale bar), the map reflects

your updates. You can select, reposition, and modify map elements. Right-

click a selected element to access its shortcut menu and set additional

options.

5. Add other text or graphics, such as notes, borders, and frames, using

the Draw toolbar. You can use guides, grids, and rulers to help you

precisely position elements on your page.

http://resources.arcgis.com/en/help/main/10.1/0066/006600000004000000.htm


6. Print or publish your map. Under the file menu you have the options to

open the Page and Print Setup dialog box, Print Preview, Print the

page, or to Export Map.

Manual to basic gis

Engineering