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NAME

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

KEYWORDS

       imagery, aerial, photo, georectification, GCP, GUI

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:

           ·   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.

           ·   The  two  panels in the lower part are used for map and GCP display, the left pane
               showing a map from the source location and the right pane showing a reference  map
               from  the  target  location.  Numbered Ground Control Points are shown on both map
               displays.

   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 canvas separately.

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

       Statusbar

       At  the  bottom of the GCP Manager is a statusbar providing several functions. 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
           Display map
           Displays maps for source and target canvas and re-renders any layers that have changed
           since the last time the display was updated.

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

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

           Define GCP (Ground Control Points)
           On left mouse click, coordinates are defined for the currently selected GCP.

           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.

           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 defined 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).

           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 resolution 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).

           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 extents of the target
           display.

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

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

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

         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 different 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 deviation * 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 highest 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 Display.

       Color for selected GCP
           Set the color for the currently selected GCP on the GCP Map Display.

       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.

         Show Help
           Show help page for the GCP Manager.

         Quit
           Quit the GCP Manager.

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

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

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

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

         Reload GCPs from POINTS file
           Reloads GCPs from the imagery group’s POINTS file.

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

         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  regular  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 centered on the given GCP. Clicking on the
       map canvas will update coordinates 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

       $Date: 2017-11-03 18:21:39 +0100 (Fri, 03 Nov 2017) $

SOURCE CODE

       Available at: wxGUI GCP Manager source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.1 Reference Manual