Georeferencing toolbar tools (Maritime Charting)

Georeferencing toolbar

The Georeferencing toolbar is used to georeference raster and CAD data.

The toolbar has a collection of drop-down items and interactive tools. There are also other components that you can use to make georeferencing your data easier.

Georeferencing toolbar drop-down items

The toolbar has a drop-down list of tools for controlling the georeferencing process.

Georeferencing toolbar drop-down menu

Item	Function
Update Georeferencing	Saves the transformation with the raster.
Rectify	Creates a new transformed raster dataset.
Fit To Display	Shifts the raster to the current display extent area.
Update Display	Updates the display with the current transformation. This is useful when Auto Adjust is disabled.
Auto Adjust	Updates the display with each link that is created.
Flip or Rotate	Corrects for common scanning distortions.
Transformation	Sets the transformation.
Delete Control Points	Deletes all the control points.
Reset Transformation	Resets the raster back to its original location. The control points are not deleted.
Options	Opens the Georeferencing Options window.

Georeferencing toolbar drop-down items described

Georeferencing toolbar drop-down Options window

The Georeferencing Options window allows you to specify default behaviors while you are georeferencing.

Georeferencing Options dialog box controls

Button or checkbox	Button name	Function
	From point symbol	Opens the Symbol Selector window to allow you to choose any point symbol as your from-point.
	To point symbol	Opens the Symbol Selector window to allow you to choose any point symbol as your to-point.
	Residual	Opens the Symbol Selector window to allow you to choose any line symbol as your residual line.
Residual		Check this box to show the residuals and RMS error in the link table. The residual shows you the error in the same units as the data frame spatial reference.
Inverse Residual		Check this box to show the inverse residuals and inverse RMS error in the link table. The inverse residual shows you the error in the pixels.
Forward-Inverse Residual		Check this box to show the forward-inverse residuals and RMS error in the link table. This is a measure of how close your accuracy is, measured in pixels. First the transformation is used to find a point in the forward direction. Then that point is used with the inverse transformation and mapped back to image space. This second point is then compared to your from-point that the link tool created.
Auto complete		Check this box to automatically show the user where the system thinks the corresponding to-point should be. Autocomplete only works when you georeference your layer to another raster, after the first two points have been created. When Autocomplete finds a more suitable link pair, it may adjust the from-point that you specified. If no corresponding point can be found, you may need to manually specify the to-point.
Maximum number of sampling blocks		Choose how many sampling blocks to use while autoregistering your raster dataset. Use the drop-down box to choose the number of resampling blocks. The default is to use as many sampling blocks as necessary.

Georeferencing Options dialog controls described

Georeferencing toolbar interactive tools

The toolbar has a collection of interactive tools for graphically controlling the georeferencing process.

Georeferencing toolbar interactive tools

Tool		Name	Function
		Add Control Points	Allows you to select control points from a layer and add them to the map.
		Auto Registration	Automatically creates links for your source raster against a target raster. The source raster must be in a relatively close geographic location in order for the autoregistration to work. See Georeferencing a raster automatically for steps to perform autoregistration.
		Select Link	Selects and highlights a link within the display.
		Zoom To Selected Link	Centers and zooms in to a selected link. If you want to zoom in further, you can click this tool multiple times.
		Delete Link	Deletes the selected link.
		Viewer	Opens a viewer window that only displays the raster that you will be georeferencing. This window will allow you to georeference a raster using two windows.
		View Link Table	Shows links and errors in tabular form.
		Rotate	Rotates the source layer. You can manually rotate the source layer, or you can type a degrees value in the measurement text box.
		Shift	Shifts the source layer. You can manually shift the source layer, or you can type an x,y value in the measurement text box.
		Scale	Rescales the source layer. You can manually rescale the source layer, or you can type a rescale factor in the measurement text box.
		Measurement	Type in the rotation angle, x,y shift, or rescale factor.

Georeferencing toolbar interactive tools described

Image Viewer window

The Image Viewer window can be accessed by clicking on the Viewer button. It is very useful when you are trying to georeference one raster dataset to another by allowing you to see both the source raster and the referenced layers at the same time. This window displays the raster dataset you are trying to georeference in its own window. If you have dual monitors, you can drag the Image Viewer window to the second monitor. If you only have one monitor available, you can use the Reposition button to divide your screen evenly for each window.

Image Viewer window buttons and their functions

Button	Name	Function
	Zoom In	Zoom in by clicking once or dragging a box in the Image Viewer window. Shortcut: Press and hold the Z keyboard shortcut.
	Zoom Out	Zoom out by clicking once or dragging a box in the Image Viewer window. Shortcut: Press and hold the X keyboard shortcut.
	Pan	Pan the ungeoreferenced raster in the Image Viewer window. Shortcut: Press and hold the C keyboard shortcut.
	Full Extent	Zoom to the full extent of the ungeoreferenced raster in the Image Viewer window.
	Fixed Zoom In	Zoom in on the center of the Image Viewer window.
	Fixed Zoom Out	Zoom out from the center of the Image Viewer window.
	Go Back To Previous Extent	Go to the previous extent of the Image Viewer window when linked to the main data view. Shortcut: Press SHIFT+<.
	Go To Next Extent	Go forward through the sequence of extents that you have been viewing in the Image Viewer window when linked to the main data view. Shortcut: Press and hold SHIFT+>.
	Refresh	Redraw the current extent of the Image Viewer window. Shortcut: Press the F5 keyboard shortcut.
	Reposition	Display both the main ArcMap window and the Image Viewer window, side by side.
	Link to Main Display	Link the data view extent with the Image Viewer extent. The navigational buttons will all be disabled on the Image Viewer window. If you navigate the data view, the Image Viewer will show the same extent.

Image Viewer window buttons described

Link Table

The Link Table can be accessed by clicking the View Link Table button. It provides information regarding the links that have been created and the residual error associated with the links.

There are several tool that you can use to evaluate your links:

• Each link can be turned on or off to evaluate what the result would be.
• The Zoom To Selected Link tool can zoom in on the highlighted link.
• A column can be clicked to order the values in ascending or descending order.

Link Table buttons and their functions

Option or Button	Button name	Function
	Open	Opens a georeferencing link file.
	Save	Saves a georeferencing link file.
	Zoom To Selected Link	Centers and zooms in to a selected link. If you want to zoom in farther, you can click this tool multiple times.
	Delete Link	Deletes the selected link.
	Insert Link	Opens a viewer window that only displays the raster that you will be georeferencing. This window will allow you to georeference a raster using two windows.
Auto Adjust		Check this box to adjust the raster to immediately show the transformation, after each link is chosen.
Degrees Minutes Seconds		Check this box to show the coordinates in degrees/minutes/seconds. This is only valid when the data frame is using a geographic coordinate system.
Transformation		This drop-down menu allows you to choose a valid transformation. To see more transformations, you may need to choose more links.

Link Table buttons described

Georeferencing keyboard shortcuts

While you are georeferencing, there are several keyboard shortcuts available to help you perform your task easily and quickly. Many of these keyboard shortcuts are commonly used in ArcGIS.

Keyboard shortcut	Function
A	Toggle the visibility of georeferencing layer on and off
B	Continuous zoom/pan
C	Pan
Q	Roam
X	Zoom out
Z	Zoom in
Esc	Cancel link (while creating a link)
Delete	Delete selected link
Space	Disable vector snapping (while pressed down)