1wxGUI.image2target(1) GRASS GIS User's Manual wxGUI.image2target(1)
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7 The GCP Manager is a wxGUI extension which allows the user to create,
8 edit, and manage Ground Control Points. It is available from the menu
9 "File | Manage Ground Control Points".
10 The GCP Manager provides an interactive graphical interface to manage
12 and analyze Ground Control Points. A backup copy of the initial POINTS
13 file is always maintained and updated only on request (Save GCPs to
14 POINTS file). This guarantees that accidental changes are not permanent
15 and can be undone by reloading the Ground Control Points.
16 The GCP Manager must be started in the target location, not in the
18 source location.
19 The GCP Manager is structured into three panels:
21 • The topmost panel shows a list of Ground Control Points. Tools
23 to manipulate and analyze GCPs are provided in the toolbar.
24 This panel can be moved out of the GCP manager window by either
25 dragging with the caption or by clicking on the pin button on
26 the right in the caption. This panel can also be placed below
27 the map displays by dragging.
28 • The two panels in the lower part are used for map and GCP dis‐
30 play, the left pane showing a map from the source location and
31 the right pane showing a reference map from the target loca‐
32 tion. Numbered Ground Control Points are shown on both map dis‐
33 plays.
34 Components of the GCP Manager
36 Toolbars
37 Two toolbars are provided with the GCP Manager, one for managing the
39 map displays and one for managing the GCP list.
40 List of ground control points
42 The list of Ground Control Points can be sorted by clicking on a column
44 header. Clicking on a cloumn header will sort the GCPs ascending, a
45 second click on the same column will sort the GCPs descending. Overall
46 RMS error and individual RMS errors of all points are often improved if
47 the GCP with the highest RMS error is adjusted. Individual coordinates
48 can be edited by double-clicking on a row.
49 The first column holds a checkbox and displays the point number. A GCP
51 is only used for RMS error calculation and georectification if its
52 checkbox on the left is checked. Uncheck to deactivate a GCP (mark as
53 unused GCP).
54 Two panels for map display
56 The left panel is used to display a map from the source location, the
58 right panel to display a map from the target loaction. Zooming in and
59 out is always possible with the mouse wheel and done for each map can‐
60 vas separately.
61 GCPs are displayed in different colors, depending on whether a GCP has
63 a high RMS error, is currently unused or is currently selected. Option‐
64 ally, currently unused GCPs are not shown on the map display.
65 Statusbar
67 At the bottom of the GCP Manager is a statusbar providing several func‐
69 tions. The default is set to Go to GCP No. (see also below). Typing a
70 number or using the up/down arrows will center the maps on the given
71 GCP, useful with a high zoom.
72 GCP Map Display Toolbar
74 Â Display map
75 Displays maps for source and target canvas and re-renders any lay‐
76 ers that have changed since the last time the display was updated.
77 Â Re-render map
79 Re-renders both source and target canvas regardless of whether they
80 have changed or not.
81 Â Erase display
83 Erases both source and target canvas to a white background.
84 Â Define GCP (Ground Control Points)
86 On left mouse click, coordinates are defined for the currently se‐
87 lected GCP.
88 Â Pan
90 Interactive selection of a new center of view in the active display
91 monitor. Drag the pan cursor while pressing the left mouse button
92 to pan. Alternatively left-click on the new center. Panning changes
93 the location of the region displayed but not the size of the area
94 displayed or the resolution.
95 Â Zoom in
97 Interactive zooming with the mouse in the active map canvas (source
98 or target). Drawing a box or just a left click with the mouse and
99 zoom-in cursor causes the display to zoom in so that the area de‐
100 fined by the box fills the display. The map resolution is not
101 changed. Clicking with the zoom-in cursor causes the display to
102 zoom in by 30%, centered on the point where the mouse is clicked.
103 Zooming changes the display region extents (both size and location
104 of area displayed).
105 Â Zoom out
107 Interactive zooming with the mouse in the active map canvas (source
108 or target). Drawing a box or just a left click with the mouse and
109 zoom-out cursor causes the display to zoom out so that the area
110 displayed shrinks to fill the area defined by the box. The map res‐
111 olution is not changed. Clicking with the zoom-out cursor causes
112 the display to zoom out by 30%, centered on the point where the
113 mouse is clicked. Zooming changes the display region extents (both
114 size and location of area displayed).
115 Â Adjust display zoom
117 Source and target display are adjusted by using the current GCPs
118 for coordinate transformation:
119 Adjust source display to target display
121 The extents of the source display are adjusted to the current ex‐
122 tents of the target display.
123 Adjust target display to source display
125 The extents of the source display are adjusted to the current ex‐
126 tents of the target display.
127 Set active map canvas
129 Sets the currently active map canvas (source or target). Click to
130 set active map canvas for Return to previous zoom or Zoom to extent
131 of currently displayed map. Alternatively, move the mouse over the
132 map canvas to be used as active canvas.
133 Â Return to previous zoom
135 Returns to the previous zoom extent. Up to 10 levels of zoom back
136 are maintained.
137 Â Zoom to extent of currently displayed map
139 Zoom to the extent of the currently displayed map in the active map
140 canvas (source or target).
141 Â Settings
143 Shows a settings dialog for GCP management and display:
144 Symbology
146 Settings for map and GCP display:
147 Highlight highest RMS error only
149 Only the GCP with the highest RMS error will be displayed in a dif‐
150 ferent colour, both in the list of GCPs and the GCP Map Display.
151 Factor for RMS error threshold = M + SD * factor:
153 All GCPs with an RMS error larger than mean RMS + RMS standard de‐
154 viation * this factor will be displayed in a different colour, both
155 in the list of GCPs and the GCP Map Display. As a rule of thumb,
156 GCPs with an RMS error larger than M + SD * 2 are most probably
157 wrong. GCPs with an RMS error larger than M + SD * 1 are worth
158 closer inspection. This option is only available if Highlight high‐
159 est RMS error only is unchecked.
160 Color
162 Set the color for GCPs on the GCP Map Display.
163 Color for high RMS error
165 Set the color for GCPs with a high RMS error on the GCP Map Dis‐
166 play.
167 Color for selected GCP
169 Set the color for the currently selected GCP on the GCP Map Dis‐
170 play.
171 Show unused GCPs
173 If unchecked, unused GCPs will not be shown on the GCP Map Display.
174 Color for unused GCPs
176 Set the color for unused GCPs on the GCP Map Display.
177 Symbol size
179 Set the symbol size for GCPs on the GCP Map Display.
180 Line width
182 Set the line width for GCPs on the GCP Map Display.
183 Select source map to display
185 Select a source map for the left pane of the GCP Map Display.
186 Select target map to display
188 Select a target map for the right pane of the GCP Map Display.
189 Rectification
191 Settings for georectification:
192 Select rectification method
194 Set the polynomial order for georectification. This order will also
195 be used for RMS error calculation.
196 Clip to computational region in target location
198 Clip raster maps to the current computational region in the target
199 location when georectifying.
200 Extension for output maps
202 Change the extension for output map names when doing the actual
203 georectification.
204 Â Show Help
206 Show help page for the GCP Manager.
207 Â Quit
209 Quit the GCP Manager.
210 Toolbar for the GCP list
212 Â Save GCPs to POINTS file
213 The current list of GCPs is saved to the imagery group’s POINTS
214 file and to a backup copy.
215 Â Add new GCP
217 Adds a new Ground Control Point to the list and selects it for
218 editing.
219 Â Delete selected GCP
221 Deletes the currently selected GCP from the list.
222 Â Clear selected GCP
224 Resets all coordinates of the currently selected GCP to 0 (zero).
225 Â Reload GCPs from POINTS file
227 Reloads GCPs from the imagery group’s POINTS file.
228 Â Recalculate RMS error
230 Recalculates forward and backward RMS error for all GCP marked for
231 use (activated checkbox in first row).
232 Â Georectify
234 Uses i.rectify to georectify all images in the source imagery
235 group.
236 GCP Map Display Statusbar
238 The GCP map display statusbar is similar to the statusbar in the regu‐
239 lar GRASS GIS map display with two differences, Go to has been replaced
240 with Go to GCP No. and Projection has been replaced with RMS error.
241 If Go to GCP No. is selected, a GCP number can be given in the left
243 side of the statusbar and the source and target map canvas will be cen‐
244 tered on the given GCP. Clicking on the map canvas will update coordi‐
245 nates for this GCP.
246 If RMS error is selected, the overall forward and backward RMS error is
248 displayed.
249
251 wxGUI
252 wxGUI components
253 i.rectify, m.transform, v.rectify
255 See also video tutorials on GRASS Wiki.
257
259 Markus Metz
260 Based on the Georectifier (GRASS 6.4.0) by Michael Barton
261 Martin Landa, Czech Technical University in Prague, Czech Republic
262
264 Available at: wxGUI GCP Manager source code (history)
265 Accessed: Saturday Jan 21 20:42:05 2023
267 Main index | GUI index | Topics index | Keywords index | Graphical in‐
269 dex | Full index
270 © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
272GRASS 8.2.1 wxGUI.image2target(1)