1i.ortho.rectify(1)            Grass 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
30
31       --help
32           Print usage summary
33
34       --verbose
35           Verbose module output
36
37       --quiet
38           Quiet module output
39
40       --ui
41           Force launching GUI dialog
42
43   Parameters:
44       group=name [required]
45           Name of input imagery group
46
47       input=name[,name,...]
48           Name of input raster map(s)
49
50       extension=string [required]
51           Output raster map(s) suffix
52
53       resolution=float
54           Target resolution (ignored if -c flag used)
55
56       memory=memory in MB
57           Amount of memory to use in MB
58           Default: 300
59
60       method=string
61           Interpolation method to use
62           Options: nearest, linear, cubic, lanczos, linear_f, cubic_f,  lanc‐
63           zos_f
64           Default: nearest
65
66       angle=name
67           Raster map with camera angle relative to ground surface
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DESCRIPTION

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

SEE ALSO

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

AUTHOR

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

SOURCE CODE

171       Available at: i.ortho.rectify source code (history)
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173       Main  index | Imagery index | Topics index | Keywords index | Graphical
174       index | Full index
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176       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual
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180GRASS 7.8.2                                                 i.ortho.rectify(1)
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