How to Georeferencing in ArcGIS

Introduction

                                          There is a great deal of geographic data available in formats that can not be immediately integrated with other GIS data. In order to use these types of data in GIS it is necessary to align it with existing Geographically reference data this process is also called Georeferencing. The process of Georeferencing relies on the coordination of points on the scanned image [data to be georeferenced] with points on a geographically referenced data [data to which the image will be georeferenced]. by "linking" point on the image with those same locations in the geographically referenced data you will create a polynomial transformation that converts the location of the entire image to the correct geographic location. call the linked points on each data layer control points. 

The selection of control points is important:

1. They should be easy to confirm as representing the same geographic location (landmark, political boundary, etc...).
2. They should be spread across the image to be registered one suggestion is to select a control point near each of the corners of the image and few throughout the interior will often work well.
3. Good overlap between the two often dataset is also important.
4. Make sure you are clicking as close possible to the same geographic location, zooming in can help in this process.                                                     

What is Georeference?

                             Georeferencing is the internal coordinate system of a map (or) aerial image can be related to a geographic coordinate system. The relevant coordinate transforms are typically stored within the image file there are many possible mechanisms for implementing georeferencing,...

How to Georeference in ArcGIS

                                Georeference is the process of transforming a scanned map (or) aerial photograph so it appears in place in gis. by linking, connecting (associating) features on the scanned image with real world x, y coordinates. The software can progressively warp the image so it fits to other spatial datasets. This tutorial will explain how to georeference a raster image in arcgis so it can then be used as an overlay or for digitizing purposes. in this example _ a historic Toronto map will be georeferenced using a dataset.

Process,- 

(Georeferencing a Raster to a Vector)

Open ArcGIS(ArcMap):- 

STEP-1 in ArcMap add the layer residing in Map coordinates and add the raster dataset you want to Georeference.

Adding  the data with the map coordinating system first is a good practice so you do not need to set the data frame coordinating system. Note-(study area Change the coordinating system to suit you will be selected)

STEP-2 To display the Georeferencing toolbar click the customize menu and click toolbars > Georeferncing. 

STEP-3 in the table of contents, right-click a target layer and click zoom to layer.

it may be helpful to set your Extent used by Full extent Command, within the Data Frame properties, to your study area so the Zoom to Full Extent tool will automatically zoom to the full extent of your study area.

STEP-4 From the Georeferencing toolbar, click the layer drop-down arrow and choose the raster layer you want to Georeference. 

STEP-5 Click the Georeferencing drop-down menu and click Fit to Display. This displays the raster dataset in the same area as the target layers. You can also use the Shift and Rotate tools to move the raster dataset as needed. To see all the dataset, adjust their order in the table of contents.

SETP-6 Click the Add Control points tool  to add control points.

SETP-7 To add a link click a know location on the raster dataset, and click a known location on the vector layers in map the reference data.

You can also your link in the magnification window (or) the viewer window. if you are using polygons as your referenced layer, you can open the effects toolbar to adjust the transparency as you add your links.

SETP-8 Add enough link for the type of transformation you will apply. 

You need a minimum of 1 link for zero-order polynomial, 6 link for a second-order polynomial, and 10 link for a third-order polynomial (or) spline transformation.

SETP-9 Click the view link table button  to evaluate the transformation.

You can examine the residual error for each link and the root mean square RMS error. If you are satisfied with the registration, you can stop entering link.

SETP-10 Delete any unwanted link from the link table.

SETP-11 Click the Georeferencing drop-down menu and click either Update Georeferencing or Rectify. Updating the georeferencing will save the transformation information with the raster and its auxiliary files. Rectifying will create a new file with the georeferencing information.

     You don’t need the control points anymore.

     Keep the magnifier window open since you may want to use it when digitizing  the layer.

Note - Georeference Complete and Save as Referencing Map End...

ArcMap Georeference Practice Video...

Arc - Geography Information System

Geography Information System (GIS)

A Geography information system (GIS) is a framework for gathering, managing and analyzing data. Rooted in the science of geography, GIS integrates many types of data. It analyzes spatial location and organizes layers of information into visualizations using maps and 3D scenes. With this unique capability, GIS reveals deeper insights into data, such as patterns, relationships and situationsusers make smarter decisions.

What is GIS

Hundreds of thousande of organization in virtually every filed are using GIS to make maps the at communicate, perform analysis, share information, and solve complex problems around the world. This is changing the way the world works.

How GIS woks

GIS technology applies geographic science with tools for understanding and collaboration. it helps people reach a common goal: to gain actionable intelligence from all types of data.

Maps

Maps are the geographic container for the data layers and analytics you want to work with GIS maps are easily shared and embedded in apps and accessible by virtually everyone, everywhere. 

Data

GIS integrates many different kind of data layer using spatial location. Most data has a geographic component. GIS data includes imagery, feature and base maps linked to spreadsheets and tables.  

Analysis

Spatial analysis lets you evaluate suitability and capability, estimate and predict, interpret and understand and much more, lending new perspective to your insight and decision - making.

Apps

Apps provide focused user experience for getting work done and bringing GIS to life for everyone. GIS apps work virtually everywhere: on your  mobile phones, tablets, in web browsers and on desktops.

 Geo is Nothing But, geo is Earth...

 What is map:

                             A Example:

                         The creating a map to get to your house. A map is a visual representation of an (GEO) entire area (or) a part of an area.

 cartographer:

                         A cartographer is a person who makes maps and charts, Art (or) technique of making maps (or) charts is called cartography.

 Types of maps:

                         1). Physical (or) Relief maps

                         2). Political maps

                         3). Thematic maps

 1). Physical (or) Relief maps:

                                                   The map that we see here is a physical map show the physical features of an area.

    

such as the mountains, rivers and lakes, platen. by using colors.                           

   The water is shown in blue, green is used for showing plain areas.

   brown is used for showing mountains (or) hills.

 2). Political maps:

                              The map shown here is a political map.

political maps shown the states, national boundaries, capital and major cities of a country.

 3). Thematic maps:

                                The map shown here is a thematic map.

Thematic map give details about different aspects of different places such as weather, transport, tourist attractions. they cover a certain theme (or) topic.

 what is a map Legend?

                                      A map Legend is included with a map to unlock it. it gives you the information needed for the to make sense. map often use symbols (or) colors to represent things and the map legend explains what they mean. symbols in the legend might be pictures (or) icons that represent different things on the map.

 What is  Geo mapping?

A process of determining locations and adjacency of different types of goods displayed in a store.

A graphical representation of a process, structure or system that depicts arrangement of and relationships among its different components.

       Traces Flows Of Energy

  Goods

Information

Materials

Money

Personnel

   See also mind Geo mapping.

 Type Of  Images File Format:

                                          JPEG File

                                           TIFF File

                                           GIF File

                                           PNG File   

                                           EPS File

 What is JPEG file?

     A computer format for recording still (Joint Photographic Experts Group) Color image, particulars  photographs with millions of colors, a computer  files saved in this format.

 What is TIF file?

     Multiple image transport to keep file together (Tagged  image file format)

Useful for transporting multiple images, Capable of storing multiple images.

Disadvantages_ Often creates large file size.

 What is GIF file?

     A single GIF image palette is limited to 256  colors, this means it is not often used for digital photographs.(Graphics interchange format) GIF file are used in business for things such as  web design animated sprites (for games) power points.  Almost every computer supports them.

 What is PNG?

     Supports up to 48-bpi will not degrade quality over time true replication decreased file size supports up to 48-bpi varied transparently.

Disadvantages_ Normally unable to reach JPEG file reduction (10mb-11mb)

 What is EPS file?

      It also usually contains a bit map version of the  image for simpler viewing rather than the vector instructions to draw the image.

EPS is a file extension for a graphics file format used in vector-based images in adobe illustrator.

 What is Shape file?

      The shape file format is a Geo spatial vector data format for geographic information system (GIS) software the shape files format can spatiany describe vector features.

(point, Line and Polygons representing for example water wells, rivers, and lakes).

 Geography Information System(GIS)

   Geography information system are computer based systems that can deal with virtually any type of information about features that can be referenced by geographical location. These systems are capable of handling both locational data and attribute data about such features. That is, not only do GIS permit the automated mapping (or) display of the location of Features, but also these systems provide a capability for recording and analyzing descriptive Characteristics about the features. For example, a GIS might contain not only a ‘map’ of the locations of road but also a database of descriptors about each road. These ‘attributes’ might include information such as road width, pavement type, speed limit, number of traffic lanes, data of construction, not so on. Table 1.1 lists other examples of attributes that might be associated with a given point, line, or area feature.

   Much of the power of a GIS comes from the database management system (DBMS) that is designed to store and manipulate these attribute data. Many GISs employ a relational database, consisting of tables, or ‘relations’, with attributes in columns and data records, or ‘tuples’ in rows (Example-1.1).

(Example-1.1)

Example-1.1 point, line, and area features and typical attributes contained in a GIS. 

Point feature well (depth, chemical constituency). Line feature power line (service capacity, age, insulator type). Area feature soil mapping unit (soil type, texture color, permeability).

              Recently there has been interest in object oriented databases, in which data objects take on more complex properties of their own. while database implementations vary, there are certain desirable characteristics that will improve the utility of a database in a GIS. These characteristics include flexibility, to allow a wide range of database queries and  operations; reliability, to avoid accidental loss of data; security, to limit access to authorized users; and ease of use, to insulate the end user from the details of the database implementation. Often the user can interact with the DBMS to search for information by means of “queries” simple commands (or) questions in a language that can be understood by the DBMS. The most common query language is known as for SQL, (or) structured query language, and several accepted standards for SQL have been adopted. 

  

                   One of the most important benefits of a gis is the ability to spatially interrelate multiple types of information stemming from a range of sources. This concept is illustrated in figure 1.25, where we have assumed that a hydrologist wishes to use a gis to study soil erosion in a watershed. As shown, the system contains data from a range of source maps (a) that have been geocoded on a cell-by-cell basis to from a series of land data files, (or) layers (b), all in geographic registration. The analyst can then manipulate and overlay the information contained in, (or) derived from, the various data files. In this example, we assume that assessing the potential for soil erosion throughout the watershed involves the simultaneous cell-by-cell consideration of three types of data.

        Derived from the original data files:   slope, soil erodibility, and surface runoff potential. The slope information can be computed from the elevations in the topography file. The erodibility, which is an attribute associated with each soil type, can be extracted from a relational database management system incorporated in the GIS. Similarly, the runoff potential is an attribute associated with each land cover type (land cover data can be obtained through interpretation of aerial photographs (or) satellite image). The analyst can use the system to interrelate these three sources of derived data (c) in each gird cell and use the result to locate, display, and/or   record areas where combinations of site characteristics indicate high soil erosion potential (i.e., steep slopes and highly erodible soil-cover combinations). 

               The above example illustrates the GIS analysis function commonly referred to as overlay analysis.  The number, from, and complexity of other data analysis possible with a GIS are virtually limitless. Such procedures can operate on the system’s spatial data, the attribute data, (or) both. For example, aggregation is an operation that permits combining detailed map categories to create new, less detailed category (e.g., combining “jack pine” and “red pine” categories into a single “pine” category). Buffering creates a zone of specified width around one (or) more features (e.g., the area within 50 m of a stream). Network analysis permits such determinations as finding the shortest path through a street network, determining the stream flows in a drainage basin, (or) finding the optimum location for a fire station. Intervisibility operations use elevation data to permit viewshed mapping of what terrain features can be “seen” from a specified location. Similarly, many GISs permit the generation of perspective view portraying terrain surface from a viewing position other than vertical.

               Several constraints need to be considered when combining data from multiple sources in a GIS, as in the example illustrated in figure 1.25 Obviously, all of the data layers must cover the same geographic area, (or) at least partially overlap. An equally important consideration is that the data layers must share the same geographic cording system. While a GIS can convert data from one coordinate system to another, it is necessary for the user to understand the characteristics of the various types of coordinate systems that may be used.

What is GIS? (Definition)

A computer system that can be used to storage view  process analyst manage and integrate geographic information.

Application:

                      A) Decision making

                      B) Data management and integration

                      c) Disaster control

What is GIS data?

Spatial Data: where is it? 

Spatial information shows the relationship between location and shapes of geographic features.

Attribute  Data: what is it?

Attribute data visually consisted by several columns which represented  to different geographic features.

Attribute Data: Information    

Storage the geographic information by a table which connected to different features.

 For example: attribute of  India include its name population GDP and other information to this country.

GIS Data:

                           Two types GIS data one vector data next one raster data.

                                            (Vector Data and Raster Data) 

Vector Data:

                       Vector data consists of individual points, which (for 2D data) are stored as pairs of X.Y co-ordinates. The point may be joined in a particular order to create lines, (or) joined into closed rings to create polygons. (Point, Line, Polygon)

There are three main vector data ty/pes in GIS are:-

Vector Data:

             Geometry types in vector data are point line polygon.

Point:

           vector points are simply X.Y coordinates.

Generally they are a latitude and longitude with a spatial reference frame. when features are too small to be represented as polygons. points and used.

 Example: House, population etc...

Line:
              vector lines connect each vertex with with paths.

Basically, you're connecting the dots in a set order and it becomes a vector line with each dot representing a vertex.

 Example: Road, River and Railway line etc..

 Polygon: 

                 when you join a set of vertices in a particular order and close it, this is now a vector polygon feature.

 Raster data:

             The Raster data is made up of pixel has an associated value. simplifying slightly a digital photograph is an example of a raster dataset where each pixel value corresponds to a particular color. 

        in GIS, the pixel values may represent elevation above sea level (or) chemical concentration (or) rainfall etc...

There are five main raster data types in GIS are:-

satellite Imagery:

                               satellite imagery are image of the earth or other planets collected by imaging satellites operated by government and businesses around the world. such data are recorded in raster format.

satellite images can be displayed in black and white (or) in color. satellite images can also simulate color photographs if they have pixel values form the red, green and blue spectral bands.

Binary scanned File:

                                    A binary image is one that consists of pixels that can have one of exactly two colors, usually black and white. Binary image also called bi-level or two-level. This means that each pixel is stored as a single bit- i.e., ao or 1.

Graphic File:

                         In this type of raster data we can include maps, 

photographs and images which can be stored as digital graphic files.

Major popular graphic files in raster format are: (GIF, PNG, JPEG)

  GIF -  Graphic Interchange Format.

PNG - Portable Network Graphics.

           JPEG - Joint Photographic Experts Group.

 

Digital Elevation Models:

                                             A digital elevation model (DEM) consist of an array of uniformly spaced elevation data. A digital elevation is point - based, but can easily be converted to raster data by placing each elevation point at the center of a call.

             

 

Digital Orthophotos:

                                     A digital orthophotos quad (DOQ) is a digital image prepared from an aerial photographs or other remotely sensed data, in which the displacement caused by camera tilt and terrain relief has been removed.     

This modal Raster data:

 Vector Files Modal:

 Geo file: 

Super GIS internal data format. 

Geo file comprises two file .geo, .dbf. 

The attribute table is stored in dbase (dbf )file format.

 Shape file:

Shape file is the most vector file format in the most commercial or publish  GIS software. 

Shape file comprises SHP, DTB, SHX, the attribute table is stored in base dbf. file format.

 Coordinate system:-

 Ex: WGS 1984 ITRF 2008.

 Projected coordinate  system.

 Ex: UTM transverse Mercator. 

 Geographic coordinate system:

Represent any location on earth by longitude and latitude.

Ex: TYPHOON,EATHQUAKE. 

The green which England was established the position of zero degree longitude  and  the equator has a zero degree latitude. 

 Latitude:

The o of latitude is called the equaled and the equator divides the globe into Vert hem and southern Harris spheres.

  Longitude:

A line which was intended to pass though the green which (LondoUK)  Was choose as the international zero longitude.

  

 Projected coordinate system:

A projected coordinate system is expressed the location on three dimensional by a flat two dimensional surface which causes distortion in the shape area distance or direction of the data.

 Advantage:

   Calculate,

                      After projecting meter can be the universe calculate unit.

    Record,

                   Most maps are recorded by two dimension maps form. 

 Projection:
                         

                                                  Earth-3D and 2D

   

 

 

 Scale:

 what is scale map:

                          Maps scale is the relationship between a unit of length  on the map and corresponding length on the ground.

Example:- Square ='1cm' on the map ='200km' on the ground.

 cartographer:

A cartographer is a person who makes maps and charts

Art (or) technique of making maps (or) charts is called cartography.