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g.gui.image2target(1)	    GRASS GIS User's Manual	 g.gui.image2target(1)

NAME
       g.gui.image2target   -  Georectifies  a	map and	allows managing	Ground
       Control Points for 3D correction.

KEYWORDS
       imagery,	GUI, aerial, photo, georectification, geometry,	GCP

SYNOPSIS
       g.gui.image2target
       g.gui.image2target --help
       g.gui.image2target  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       --help
	   Print usage summary

       --verbose
	   Verbose module output

       --quiet
	   Quiet module	output

       --ui
	   Force launching GUI dialog

DESCRIPTION
       The GCP Manager is a wxGUI extension which allows the user  to  create,
       edit,  and  manage Ground Control Points. It is available from the menu
       "File | Manage Ground Control Points".

       The GCP Manager provides	an interactive graphical interface  to	manage
       and  analyze Ground Control Points. A backup copy of the	initial	POINTS
       file is always maintained and updated only on  request  (Save  GCPs  to
       POINTS file). This guarantees that accidental changes are not permanent
       and can be undone by reloading the Ground Control Points.

       The GCP Manager must be started in the  target  location,  not  in  the
       source location.

       The GCP Manager is structured into three	panels:

	   o   The  topmost panel shows	a list of Ground Control Points. Tools
	       to manipulate and analyze GCPs are  provided  in	 the  toolbar.
	       This panel can be moved out of the GCP manager window by	either
	       dragging	with the caption or by clicking	on the pin  button  on
	       the  right in the caption.  This	panel can also be placed below
	       the map displays	by dragging.

	   o   The two panels in the lower part	are used for map and GCP  dis-
	       play,  the left pane showing a map from the source location and
	       the right pane showing a	reference map from  the	 target	 loca-
	       tion. Numbered Ground Control Points are	shown on both map dis-
	       plays.

   Components of the GCP Manager
       Toolbars

       Two toolbars are	provided with the GCP Manager, one  for	 managing  the
       map displays and	one for	managing the GCP list.

       List of ground control points

       The list	of Ground Control Points can be	sorted by clicking on a	column
       header. Clicking	on a cloumn header will	sort  the  GCPs	 ascending,  a
       second  click on	the same column	will sort the GCPs descending. Overall
       RMS error and individual	RMS errors of all points are often improved if
       the  GCP	with the highest RMS error is adjusted.	Individual coordinates
       can be edited by	double-clicking	on a row.

       The first column	holds a	checkbox and displays the point	number.	A  GCP
       is  only	 used  for  RMS	 error calculation and georectification	if its
       checkbox	on the left is checked.	Uncheck	to deactivate a	GCP  (mark  as
       unused GCP).

       Two panels for map display

       The  left  panel	is used	to display a map from the source location, the
       right panel to display a	map from the target loaction. Zooming  in  and
       out  is always possible with the	mouse wheel and	done for each map can-
       vas separately.

       GCPs are	displayed in different colors, depending on whether a GCP  has
       a high RMS error, is currently unused or	is currently selected. Option-
       ally, currently unused GCPs are not shown on the	map display.

       Statusbar

       At the bottom of	the GCP	Manager	is a statusbar providing several func-
       tions.  The default is set to Go	to GCP No. (see	also below).  Typing a
       number or using the up/down arrows will center the maps	on  the	 given
       GCP, useful with	a high zoom.

   GCP Map Display Toolbar
       A    Display map
	   Displays  maps for source and target	canvas and re-renders any lay-
	   ers that have changed since the last	time the display was updated.

       A    Re-render map
	   Re-renders both source and target canvas regardless of whether they
	   have	changed	or not.

       A    Erase display
	   Erases both source and target canvas	to a white background.

       A    Define GCP (Ground Control Points)
	   On  left mouse click, coordinates are defined for the currently se-
	   lected GCP.

       A    Pan
	   Interactive selection of a new center of view in the	active display
	   monitor.  Drag  the pan cursor while	pressing the left mouse	button
	   to pan. Alternatively left-click on the new center. Panning changes
	   the	location  of the region	displayed but not the size of the area
	   displayed or	the resolution.

       A    Zoom in
	   Interactive zooming with the	mouse in the active map	canvas (source
	   or  target).	 Drawing a box or just a left click with the mouse and
	   zoom-in cursor causes the display to	zoom in	so that	the  area  de-
	   fined  by  the  box	fills  the  display. The map resolution	is not
	   changed. Clicking with the zoom-in cursor  causes  the  display  to
	   zoom	 in  by	30%, centered on the point where the mouse is clicked.
	   Zooming changes the display region extents (both size and  location
	   of area displayed).

       A    Zoom out
	   Interactive zooming with the	mouse in the active map	canvas (source
	   or target). Drawing a box or	just a left click with the  mouse  and
	   zoom-out  cursor  causes  the  display to zoom out so that the area
	   displayed shrinks to	fill the area defined by the box. The map res-
	   olution  is	not  changed. Clicking with the	zoom-out cursor	causes
	   the display to zoom out by 30%, centered on	the  point  where  the
	   mouse  is clicked. Zooming changes the display region extents (both
	   size	and location of	area displayed).

       A    Adjust display zoom
	   Source and target display are adjusted by using  the	 current  GCPs
	   for coordinate transformation:

       Adjust source display to	target display
	   The	extents	 of the	source display are adjusted to the current ex-
	   tents of the	target display.

       Adjust target display to	source display
	   The extents of the source display are adjusted to the  current  ex-
	   tents of the	target display.

       Set active map canvas
	   Sets	 the  currently	active map canvas (source or target). Click to
	   set active map canvas for Return to previous	zoom or	Zoom to	extent
	   of  currently displayed map.	Alternatively, move the	mouse over the
	   map canvas to be used as active canvas.

       A    Return to previous zoom
	   Returns to the previous zoom	extent.	Up to 10 levels	of  zoom  back
	   are maintained.

       A  Zoom to extent of currently displayed	map
	   Zoom	to the extent of the currently displayed map in	the active map
	   canvas (source or target).

       A  Settings
	   Shows a settings dialog for GCP management and display:

       Symbology
	   Settings for	map and	GCP display:

       Highlight highest RMS error only
	   Only	the GCP	with the highest RMS error will	be displayed in	a dif-
	   ferent colour, both in the list of GCPs and the GCP Map Display.

       Factor for RMS error threshold =	M + SD * factor:
	   All	GCPs with an RMS error larger than mean	RMS + RMS standard de-
	   viation * this factor will be displayed in a	different colour, both
	   in  the  list  of GCPs and the GCP Map Display. As a	rule of	thumb,
	   GCPs	with an	RMS error larger than M	+ SD *	2  are	most  probably
	   wrong.  GCPs	 with  an  RMS	error larger than M + SD * 1 are worth
	   closer inspection. This option is only available if Highlight high-
	   est RMS error only is unchecked.

       Color
	   Set the color for GCPs on the GCP Map Display.

       Color for high RMS error
	   Set	the  color  for	GCPs with a high RMS error on the GCP Map Dis-
	   play.

       Color for selected GCP
	   Set the color for the currently selected GCP	on the	GCP  Map  Dis-
	   play.

       Show unused GCPs
	   If unchecked, unused	GCPs will not be shown on the GCP Map Display.

       Color for unused	GCPs
	   Set the color for unused GCPs on the	GCP Map	Display.

       Symbol size
	   Set the symbol size for GCPs	on the GCP Map Display.

       Line width
	   Set the line	width for GCPs on the GCP Map Display.

       Select source map to display
	   Select a source map for the left pane of the	GCP Map	Display.

       Select target map to display
	   Select a target map for the right pane of the GCP Map Display.

       Rectification
	   Settings for	georectification:

       Select rectification method
	   Set the polynomial order for	georectification. This order will also
	   be used for RMS error calculation.

       Clip to computational region in target location
	   Clip	raster maps to the current computational region	in the	target
	   location when georectifying.

       Extension for output maps
	   Change  the	extension  for	output map names when doing the	actual
	   georectification.

       A  Show Help
	   Show	help page for the GCP Manager.

       A  Quit
	   Quit	the GCP	Manager.

   Toolbar for the GCP list
       A  Save GCPs to POINTS file
	   The current list of GCPs is saved to	 the  imagery  group's	POINTS
	   file	and to a backup	copy.

       A  Add new GCP
	   Adds	 a  new	 Ground	 Control  Point	to the list and	selects	it for
	   editing.

       A  Delete selected GCP
	   Deletes the currently selected GCP from the list.

       A  Clear	selected GCP
	   Resets all coordinates of the currently selected GCP	to 0 (zero).

       A  Reload GCPs from POINTS file
	   Reloads GCPs	from the imagery group's POINTS	file.

       A  Recalculate RMS error
	   Recalculates	forward	and backward RMS error for all GCP marked  for
	   use (activated checkbox in first row).

       A  Georectify
	   Uses	 i.rectify  to	georectify  all	 images	 in the	source imagery
	   group.

   GCP Map Display Statusbar
       The GCP map display statusbar is	similar	to the statusbar in the	 regu-
       lar GRASS GIS map display with two differences, Go to has been replaced
       with Go to GCP No. and Projection has been replaced with	RMS error.

       If Go to	GCP No.	is selected, a GCP number can be  given	 in  the  left
       side of the statusbar and the source and	target map canvas will be cen-
       tered on	the given GCP. Clicking	on the map canvas will update  coordi-
       nates for this GCP.

       If RMS error is selected, the overall forward and backward RMS error is
       displayed.

SEE ALSO
	wxGUI
       wxGUI components

	i.rectify, m.transform,	v.rectify

       See also	video tutorials	on GRASS Wiki.

AUTHORS
       Markus Metz
       Based on	the Georectifier (GRASS	6.4.0) by Michael Barton
       Martin Landa, Czech Technical University	in Prague, Czech Republic

SOURCE CODE
       Available at: wxGUI GCP Manager source code (history)

       Main index | GUI	index |	Topics index | Keywords	index |	Graphical  in-
       dex | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.4 Reference	Manual

GRASS 7.8.4						 g.gui.image2target(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | SEE ALSO | AUTHORS | SOURCE CODE

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