This work is an effort to share Geographical Information System: This presentation will present you both ways to geo reference image: 1. Raw image by X,Y coordinates 2. Image to Image referencing

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Image
Geo-referencing
Arch GIS
Pt.LC State University of Performing and Visual Arts
Rohtak, Haryana.
Simran Vats
2nd sem, MURP

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What is Georeferencing
 Georeferencing is the process of taking a digital image,
it could be an airphoto, a scanned geologic map, or a
picture of a topographic map, and adding geographic
information to the image so that GIS or mapping
software can 'place' the image in its appropriate real
world location. This process is completed by selecting
pixels in the digital image and assigning them
geographic coordinates. In rare instances, one may
already know the geographic coordinates of certain
pixels in an image; more frequently, a non-
georeferenced image is georeferenced to an existing
image that already has embedded geographic
information

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Georeferencing a raw image entering
x,y coordinates
 You can georeference a raster to specific x,y or
degrees/minutes/seconds (DMS) coordinates. When
georeferencing to specific target coordinates, you
still need to choose the appropriate well-defined
objects in your images, such as road intersections or
graticules. For example, you may have a scanned
map or aerial photos that have coordinates already
shown on your image, such as latitude and longitude
coordinates.
 To perform this workflow, you must know of ground
control points on the source image and the
coinciding latitude and longitude coordinates.

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 In ArcGIS, add the source raster that you want to georeference.
 In the Contents pane, click the source raster layer you want to georeference.
 Right-click the source raster and click Zoom to Layer.
 To display the Georeference tab, click the Imagery tab and click Georeference.
The tools on the Georeference tab are split into several groups to help you use
the correct tool in the proper phase of your georeferencing session.
 In the Prepare group, click Set SRS .If your raster dataset already has a spatial
reference, it will be automatically used as the coordinate system for the map and
the georeferencing session. If your raster dataset does not have a spatial
reference, the Map Properties dialog box will appear, and you can choose the
coordinate system to set for the georeferencing session; the default spatial
reference is the current coordinate system of the map.
 In the Adjust group, turn off the Auto Apply tool .Auto Apply was turned off so
that the image does not move each time you create your control points.

5. z In the Adjust group, click the Add Control Points tool to create control
points.To add a control point, first click a location on the raster you are
georeferencing (the source layer), and then click the same location on the target
layer in the map (the reference data).
 Click a known location within the raster you are georeferencing (the source
layer).
 Right-click to bring up the Target Coordinates dialog box.
 Enter the corresponding x- and y-coordinates for this location.
 Click OK.
 Repeat the previous step with all the known coordinate points that you have.
 In the Review group, click the Control Point Table button to evaluate the
residual error for each control point.
 Press the L key to toggle the transparency of your source raster on and off.
 Delete any unwanted control points using the Control Point Table.
 If you're satisfied with the current alignment, stop entering control points.
 In the Save group, choose how you want to persist your georeferencing
information
Steps

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Image to Image referencing
 You can georeference a raster to either another raster
layer or a feature class. When georeferencing, you should
look for well-defined objects in your images, such as road
intersections or land features. These objects should be on
the ground and not elevated features. This way, you can
be certain that you are referencing the same location in
both the raster and aligned layers. To perform this
workflow, you must know of ground control points on the
source image and the coinciding latitude and longitude
coordinates.
 The raster layer you are georeferencing must either be in
the same coordinate system as the map frame or have no
spatial reference defined.

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Steps
 In ArcMap, add the layers residing in map coordinates and add the raster dataset you
want to georeference.
 Adding the data with the map coordinate system first is a good practice so you do not
need to set the data frame coordinate system.
 To display the Georeferencing toolbar, click the Customize menu and click Toolbars >
Georeferencing.
 In the table of contents, right-click a target layer (the referenced dataset) 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.
 From the Georeferencing toolbar, click the Layer drop-down arrow and choose the
raster layer you want to georeference.
 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 datasets, adjust their
order in the table of contents.

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 Click the Add Control Points tool to add control points.
 To add a link, click a known location on the raster dataset, and click a known location on the
vector layers in map (the reference data).
 You can also add your links 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.
 Tip:Press Esc to remove a link while you're in the middle of creating it.
 Source:
 https://pro.arcgis.com/en/pro-app/help/data/imagery/georeferencing-a-raster-automatically-to-
another-raster.htm
Steps

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Thank you!