1i.ortho.rectify(1)          GRASS GIS User's Manual         i.ortho.rectify(1)
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NAME

6       i.ortho.rectify   - Orthorectifies an image by using the image to photo
7       coordinate transformation matrix.
8

KEYWORDS

10       imagery, orthorectify
11

SYNOPSIS

13       i.ortho.rectify
14       i.ortho.rectify --help
15       i.ortho.rectify  [-ca]  group=name    [input=name[,name,...]]    exten‐
16       sion=string      [resolution=float]       [memory=memory     in     MB]
17       [method=string]   [angle=name]   [--overwrite]   [--help]   [--verbose]
18       [--quiet]  [--ui]
19
20   Flags:
21       -c
22           Use  current  region  settings  in  target location (def.=calculate
23           smallest area)
24
25       -a
26           Rectify all raster maps in group
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28       --overwrite
29           Allow output files to overwrite existing files
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31       --help
32           Print usage summary
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34       --verbose
35           Verbose module output
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37       --quiet
38           Quiet module output
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40       --ui
41           Force launching GUI dialog
42
43   Parameters:
44       group=name [required]
45           Name of input imagery group
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47       input=name[,name,...]
48           Name of input raster map(s)
49
50       extension=string [required]
51           Output raster map(s) suffix
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53       resolution=float
54           Target resolution (ignored if -c flag used)
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56       memory=memory in MB
57           Maximum memory to be used (in MB)
58           Cache size for raster rows
59           Default: 300
60
61       method=string
62           Interpolation method to use
63           Options: nearest, linear, cubic, lanczos, linear_f, cubic_f,  lanc‐
64           zos_f
65           Default: nearest
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67       angle=name
68           Raster map with camera angle relative to ground surface
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DESCRIPTION

71       i.photo.rectify  rectifies an image by using the image to photo coordi‐
72       nate transformation matrix created by i.photo.2image and the rectifica‐
73       tion  parameters  created  by  i.photo.2target.   Rectification  is the
74       process by which the geometry of an image is made planimetric.  This is
75       accomplished by mapping an image from one coordinate system to another.
76       In  i.photo.rectify  the  parameters  computed  by  i.photo.2image  and
77       i.photo.2target  are used in equations to convert x,y image coordinates
78       to standard map coordinates for each pixel in the image.  The result is
79       an  image with a standard map coordinate system, compensated for relief
80       distortions and photographic tilt. Upon completion of the  program  the
81       rectified image is deposited in a previously targeted GRASS LOCATION.
82
83       Images  can  be resampled with various different interpolation methods:
84       nearest neighbor assignment, bilinear and  bicubic  interpolation.  The
85       bilinear  and  bicubic  interpolation methods are also available with a
86       fallback option. These methods "fall  back"  to  simpler  interpolation
87       methods  along NULL borders. That is, from bicubic to bilinear to near‐
88       est.
89
90       The process may take an hour or more  depending  on  the  size  of  the
91       image,  the  speed  of the computer, the number files, and the size and
92       resolution of the selected window.
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94       The rectified image will be located in the  target  LOCATION  when  the
95       program  is  completed. The original unrectified files are not modified
96       or removed.
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98       The optional angle output holds the camera  angle  in  degrees  to  the
99       local  surface,  considering  local  slope  and  aspect.  A value of 90
100       degrees indicates that the camera angle was  orthogonal  to  the  local
101       surface,  a value of 0 degrees indicates that the camera angle was par‐
102       allel to the local surface and negative values indicate that  the  sur‐
103       face  was  invisible to the camera. As a rule of thumb, values below 30
104       degrees indicate problem areas where  the  orthorectified  output  will
105       appear  blurred.  Because terrain shadowing effects are not considered,
106       areas with high camera angles may  also  appear  blurred  if  they  are
107       located  (viewed  from  the  camera position) behind mountain ridges or
108       peaks.
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110       i.photo.rectify can be run directly, specifying options in the  command
111       line   or   the  GUI,  or  it  can  be  invoked  as  OPTION  8  through
112       i.ortho.photo. If invoked though i.ortho.photo, an interactive terminal
113       is used to determine the options.
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115   Interactive mode
116       You  are  first  asked if all images within the imagery group should be
117       rectified. If this option is not chosen, you are asked to  specify  for
118       each  image  within the imagery group whether it should be rectified or
119       not.
120
121       More than one file may be rectified at a time. Each file should have  a
122       unique  output  file name. The next prompt asks you for an extension to
123       be appended to the rectified images.
124
125       The next prompt will ask you whether a camera angle map should be  pro‐
126       duced and if yes, what should be its name.
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128       After  that  you  are  asked if overwriting existing maps in the target
129       location and mapset should be allowed.
130
131       The next prompt asks you to select one of two windows:
132
133             Please select one of the following options
134             1.   Use the current window in the target location
135             2.   Determine the smallest window which covers the image
136             >
137
138       If you choose option 2, you can also specify a desired  target  resolu‐
139       tion.
140
141       i.photo.rectify will only rectify that portion of the image that occurs
142       within the chosen window.  Only that portion will be relocated  in  the
143       target  database. It is therefore important to check the current window
144       in the target LOCATION if choice number one is selected.
145
146       Next you are asked to select an interpolation method.
147             Please select one of the following interpolation methods
148             1. nearest neighbor
149             2. bilinear
150             3. bicubic
151             4. bilinear with fallback
152             5. bicubic with fallback
153             >
154
155       The last prompt will ask you about the amount of memory to be  used  by
156       i.photo.rectify.
157

SEE ALSO

159        i.ortho.photo
160       i.ortho.camera
161       i.photo.2image
162       i.photo.2target
163       i.ortho.init
164       i.rectify
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AUTHOR

167       Mike Baba,  DBA Systems, Inc.
168       Updated rectification and elevation map to FP 1/2002 Markus Neteler
169       Bugfixes and enhancements 12/2010 Markus Metz
170

SOURCE CODE

172       Available at: i.ortho.rectify source code (history)
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174       Main  index | Imagery index | Topics index | Keywords index | Graphical
175       index | Full index
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177       © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
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181GRASS 7.8.5                                                 i.ortho.rectify(1)
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