gis

GIS and Spatial PlanningPLAN204

PRACTICAL EXERCISE

Prepared By: SHAURIYA SOLANKI B.PLAN-(2014-2018)

A4134914005

Geographical Information System GIS Capabilities The Need For GIS Components of GIS Cross Disciplinary Nature of GIS Creating GIS How to combine Geographical Information How Does GIS Works Information is organized into layers: Why Is GIS Unique Top Benefits Of GIS GIS Applications Geo:- EARTH

Geography:- Study of earth and where things are.

Information:- For capturing, managing, analyzing and understanding Information.

System:- A set of Software, hardware and Data.

Geographical Information System (GIS) is a computer based information system used to digitally represent and analyze the geographic features present on the Earth’s surface and the events that taking place on it.

Geographic Infrmation Systems provide a method for integrating and analyzing spatial (digital map based) information such as "where is the nearest movie theater?"

Alongside related non-spatial information (what movies are playing there?).

Many people are becoming far more familiar with seeing the results both textually - for example when their phone shows them the nearest pub - and on open map systems such as Google Maps.

A geographic information system (GIS) is a system used to describe and characterize geographical surface of the earth for the purpose of visualizing and analysing geographically referenced information.

What is Geographic Data?Geographic data is simply a collection of information that can describe objects and things with relation to space. For e.g. Geographic data can be used to determine a variety of characteristics of a population.

Types of Geographic DataFor GIS the Geographic Data inputs are of two types:

Spatial Data Attribute Data

Spatial data is the data or information that identifies the geographic location of features and boundaries on Earth, such as natural or constructed features, oceans, and more.

Attribute data is the tabular or textual data describing the geographic characteristics of features. For instance, the spatial data might represent a county and contain information for city boundaries, census tract boundaries, streets, and so forth. An attribute data set with population information for each census tract can be linked to a map by the corresponding tract value in the spatial data.

Representation of Spatial data in GISSpatial data are represented in GIS in two formats

Raster datasets (Imagery). Vector datasets (Features [collections of points, lines, and polygons])

Imagery Imagery in GIS often refers pixel-based data sources—for satellites, aerial photography, digital elevation models, raster datasets, and so on. Imagery is managed as a raster data type composed of cells organized in a grid of rows and columns. There are different ways in which your raster and image data may be supported in ArcGIS: as a raster dataset which is derived from a storage format (for e.g. ASCII Grid; Tagged Image File Format (TIFF), Erdas Imagine), as a raster product which is derived from specific metadata files (GeoEye satellite, IKONOS satellite, Landsat satellites etc).

Features—points, lines, and polygonsGeographic features are most commonly represented as points, lines, or polygons.

Points (For e.g. well locations, telephone poles, mountain peaks etc.)

Lines (For e.g. roads, streams etc.). Polygons (For e.g. states, soil types, land-use zones etc.)

Shapefile is a way of storing points, lines and polygon features inside a file in ArcGIS. The shapefile format defines the geometry and attributes of geographically referenced features in three or more files with specific file extensions that should be stored in the same project workspace. They are

.shp—The main file that stores the feature geometry .shx—The index file that stores the index of the feature geometry. It is a positional index of the feature geometry to allow seeking forwards and backwards quickly.

.dbf—The dBASE table that stores the attribute information of features .sbn and .sbx—The files that store the spatial index of the features..prj—The file that stores the coordinate system information.

When copying shapefiles, it is recommended that you do so in ArcCatalog. However, if you copy a shapefile outside ArcGIS, be sure to copy all the files that make up the shapefile. .shp, .shx, and .dbf are mandatory to store the core data that comprise a shapefile.

Representation of Attribute data in GIS

In a GIS, descriptive attributes are managed in tables. Attribute tables provide a simple, universal data model for storing and working with attribute information. Tables contain rows and columns. Each column has a type, such as integer, decimal number, character, and date.

Representation of data in ArcGIS

ArcGIS models geographic information as a logical set of layers or themes. Map layers are thematic representations of geographic information. Within each map layer, symbols, colors, and text are used to portray important information that describes each of the individual geographic elements.

DigitizationDigitizing is the process of interpreting and converting paper map or image data to vector digital data. In manual digitizing you trace the lines or points from the source media. You control a cursor, usually with a mouse, and sample vertices to define the point, line, or polygonal features you wish to capture. The source media may be hardcopy, e.g., maps taped

to a digitizing table, or softcopy, e.g., a digital image or scanned map.

EXERCISE 2: LAB ASSSIGNMENT TASK

5. Data structures : Can a property ownership map be related to a satellite

image, a timely indicator of land uses? Yes, but, because digital data are collected and stored in various ways, the two data sources may not be entirely compatible. So a GIS must be able to convert data from one structure to another.

Data restructuring can be performed by a GIS to convert data into different formats

For example, a GIS may be used to convert a satellite image map to a vector structure by generating lines around all cells with the same classification, while determining the cell spatial relationships, such as

adjacency or inclusion.

GIS organizes information in many layers. Each layer represents a particular theme or feature of map.

4. Projection & Registration: Projection is a fundamental component of mapmaking. A

projection is a mathematical means of transferring information from the Earth's three-dimensional, curved surface to a two-dimensional medium—paper or a computer screen.

Different projections are used for different types of maps because each projection is particularly appropriate for certain uses.

1.

Digital Mapping:-

If you want to use already existed maps which are not in digital form, but in a form that can be recognized by computer can be used in GIS by converting them into Digital form so that they can be used.

Relating info. from different

sources Data capture

Data integration

Projection and registration

Data structures

Data modeling

How Does GIS Works :

Maps can be digitized by hand-tracing with a computer mouse on the screen or on a digitizing tablet to collect the coordinates of feature .Electronic scanners can also convert maps to digits

2. Data Integration:

A GIS makes it possible to link, or integrate, information that is difficult to associate through any other means.

Thus, a GIS can use combinations of mapped variables to build and analyze new variables.

3. . Data Capture:

Maps can be digitized by hand-tracing with a computer

mouse on the screen or on a digitizing tablet to collect the

coordinates of features.

A GIS can be used to emphasize the spatial relationships

.

CROSS-DISCIPLINARY NATURE OF GIS

Q1. Prepare a layout map with all map elements showing some points, lines and polygon features in the toposheet (lab2.jpg). Note: (At-least 5 features in each category should be digitized)