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

6       i.ortho.photo  - Menu driver for the photo imagery programs.
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KEYWORDS

9       imagery, orthorectify, geometry
10

SYNOPSIS

12       i.ortho.photo
13       i.ortho.photo --help
14       i.ortho.photo   group=name  productname=string   [--help]   [--verbose]
15       [--quiet]  [--ui]
16
17   Flags:
18       --help
19           Print usage summary
20
21       --verbose
22           Verbose module output
23
24       --quiet
25           Quiet module output
26
27       --ui
28           Force launching GUI dialog
29
30   Parameters:
31       group=name [required]
32           Name of imagery group for ortho-rectification
33
34       productname=string [required]
35           Name of Modules
36           Options:  i.group,  i.ortho.target,  i.ortho.elev,  i.ortho.camera,
37           g.gui.photo2image,  i.ortho.init,  g.gui.image2target, i.ortho.rec‐
38           tify
39           i.group: 1 - Select/Modify imagery group
40           i.ortho.target: 2 - Select/Modify imagery group target
41           i.ortho.elev: 3 - Select/Modify target elevation model
42           i.ortho.camera: 4 - Select/Modify imagery group camera
43           g.gui.photo2image: 5 - Compute image-to-photo transformation
44           i.ortho.init: 6 - Initialize exposure station parameters
45           g.gui.image2target: 7 - Compute ortho-rectification parameters
46           i.ortho.rectify: 8 - Ortho-rectify imagery files
47

DESCRIPTION

49       i.ortho.photo is a menu to launch the different parts of the ortho rec‐
50       tification  process of aerial imagery. i.ortho.photo allows the user to
51       ortho-rectify imagery group files consisting of several scanned  aerial
52       photographs  (raster  maps) of a common area.  i.ortho.photo guides the
53       user through 8 steps required to ortho-rectify the  raster  maps  in  a
54       single  imagery  group.  Alternatively,  all the steps can be performed
55       separately by running the appropriate modules.
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57           ·   Initialization Options
58
59           ·   Create/Modify imagery group to be orthorectified: i.group
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61           ·   Select/Modify target location and  mapset  for  orthorectifica‐
62               tion: i.ortho.target
63
64           ·   Select/Modify  target  elevation model used for orthorectifica‐
65               tion: i.ortho.elev
66
67           ·   Create/Modify camera file of imagery group: i.ortho.camera
68
69           ·   Transformation Parameters Computation
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71           ·   Compute image-to-photo transformation: g.gui.photo2image
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73           ·   Initialize parameters of camera: i.ortho.init
74
75           ·   Compute  ortho-rectification  parameters  from  ground  control
76               points: g.gui.image2target
77
78           ·   Ortho-rectification
79
80           ·   Ortho-rectify imagery group: i.ortho.rectify
81
82       The  ortho-rectification procedure in GRASS GIS places the image pixels
83       on the surface of the earth by matching the coordinate  system  of  the
84       aerial  image  in  pixels  (image coordinate system) and the coordinate
85       system of the camera sensor in millimetres  (photo  coordinate  system)
86       for the interior orientation of the image, and further to the georefer‐
87       enced coordinate system defined by projection parametres (target  coor‐
88       dinate system) for exterior orientation.
89

EXAMPLE

91       Five groups of input parameters are required for ortho-rectification:
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93           ·   Aerial image (images),
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95           ·   Exposure  and  characteristics  of the camera, i.e. its coordi‐
96               nates in target coordinate system and height above  sea  level,
97               focal  length,  yaw,  pitch  and roll, dimensions of the camera
98               sensor and resolution of aerial images,
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100           ·   Reference surface, i.e. digital elevation model in  the  target
101               coordinate system used to normalize the terrain undulation,
102
103           ·   Topographic  reference  map  used  to find corresponding ground
104               control points and/or,
105
106           ·   Coordinates of ground control points in the  target  coordinate
107               system.
108       Example of an input oblique image in a source location
109
110       To  ortho-rectify aerial images the user has to follow the menu options
111       step by step. Alternatively, all the steps can be performed  separately
112       by running the corresponding modules.
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114       The  aerial  photos  shall  be  stored in a source location - a general
115       Cartesian coordinate system (XY). Digital elevation  model  and  a  map
116       reference (topo sheet or other map used for ground control point match‐
117       ing) shall be stored in a target location in  a  real-world  coordinate
118       system (e.g. ETRS33).
119
120       The steps to follow are described below:
121
122       1      Create/Modify imagery group to be orthorectified: i.group
123
124       This step is to be run in the source location.
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126       In this first step an imagery group of aerial images for ortho-rectifi‐
127       cation is created or modified. The current imagery group  is  displayed
128       at  the top of the menu. You may select a new or existing imagery group
129       for the ortho-rectification. After choosing this  option  you  will  be
130       prompted  for the name of a new or existing imagery group. As a result,
131       a new file mapset/group/name_of_group/REF is created that contatins the
132       names of all images in a group.
133       IMG_0020 source_mapset
134       IMG_0021 source_mapset
135       IMG_0022 source_mapset
136
137       2      Select/Modify target location and mapset for orthorectification:
138              i.ortho.target
139
140       This step is to be run in the source location.
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142       The target location and mapset may be selected or modified in  Step  2.
143       You will be prompted for the names of the projected target location and
144       mapset where the ortho-rectified raster maps will  reside.  The  target
145       location  is  also  the location from which the elevation model (raster
146       map)  will  be  selected  (see  Step  3).  In  Step  2,  a   new   file
147       mapset/group/name_of_group/TARGET  is  created contatining the names of
148       target location and mapset.
149       ETRS_33N
150       target_mapset
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152       3      Select/Modify target elevation model  used  for  orthorectifica‐
153              tion: i.ortho.elev
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155       This step is to be run in the source location.
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157       Step  3 allows you to select the raster map from the target location to
158       be used as the elevation model. The elevation  model  is  required  for
159       both the computation of photo-to-target parameters (Step 6) and for the
160       ortho-rectification of the imagery group files (Step  8).   The  raster
161       map  selected  for  the elevation model should cover the entire area of
162       the image group to be ortho-rectified. DTED and DEM files are  suitable
163       for use as elevation model in the ortho-rectification program.  In Step
164       3 you will be prompted for the name of the raster  map  in  the  target
165       location  that  you  want to use as the elevation model. As a result of
166       this step, a new file mapset/group/name_of_group/ELEVATION  is  created
167       contatining the name and mapset of the chosen DEM.
168       elevation layer :ELEVATION
169       mapset elevation:target_mapset
170       location        :ETRS_33N
171       math expression :(null)
172       units           :(null)
173       no data values  :(null)
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175       4
176               Create/Modify camera file of imagery group: i.ortho.camera
177
178       This step is to be run in the source location.
179
180       In Step 4 you may select or create a camera reference file that will be
181       used with the current imagery group. A camera reference  file  contains
182       information  on  the  internal characteristics of the aerial camera, as
183       well as the geometry of the fiducial or reseau marks. The  most  impor‐
184       tant  characteristic  of  the  camera  is its focal length. Fiducial or
185       reseau marks locations are required to compute  the  scanned  image  to
186       photo  coordinate  transformation parameter (Step 5). Two new files are
187       created in this step: a file mapset/group/name_of_group/CAMERA,  conta‐
188       tining  the  name  of  the  reference  camera  and  a  file mapset/cam‐
189       era/name_of_reference, contatining the camera parameters.
190       CAMERA NAME   sony
191       CAMERA ID     123
192       CAMERA XP     0
193       CAMERA YP     0
194       CAMERA CFL    16
195       NUM FID       4
196             0 -11.6 0
197             1 0 7.7
198             2 11.6 0
199             3 0 -7.7
200
201       5
202               Compute image-to-photo transformation: g.gui.photo2image
203
204       This step is to be run in the source location.
205
206       The scanned image to photo coordinate transformation  parameters,  i.e.
207       the  "interior orientation", is computed in Step 5. In this interactive
208       step you associate the  scanned  reference  points  (fiducials,  reseau
209       marks, etc.)  with their known photo coordinates from the camera refer‐
210       ence file. A new file mapset/group/name_of_group/REF_POINTS is created,
211       contatining  a  list of pairs of coordinates in image and photo coordi‐
212       nate systems.
213       # Ground Control Points File
214       #
215       # target location: XY
216       # target mapset: source_mapset
217       # source  target  status
218       # east north east north (1=ok, 0=ignore)
219       #-------------------------------------------------------------
220       0 1816     -11.6 0.0     1
221       2728 3632     0.0 7.7     1
222       5456 1816     11.6 0.0     1
223       2728 0.0     0.0 -7.7     1
224       Step 5: Image-to-photo transformation of an oblique image
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226       6
227               Initialize parameters of camera: i.ortho.init
228
229       This step is to be run in the source location.
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231       In Step 6, initial camera exposure station parameters and initial vari‐
232       ances may be selected or modified.
233
234           ·   X: East aircraft position;
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236           ·   Y: North aircraft position;
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238           ·   Z: Flight heigh above surface;
239
240           ·   Omega  (roll): Raising or lowering of the wings (turning around
241               the aircraft’s axis);
242
243           ·   Phi (pitch): Raising or lowering of the aircraft’s front (turn‐
244               ing around the wings’ axis);
245
246           ·   Kappa  (yaw): Rotation needed to align the aerial photo to true
247               north: needs to be denoted as  +90°  for  clockwise  turn  and
248               -90° for a counter-clockwise turn.
249       Principle of pitch and yaw
250
251       In  Step  6, a new file mapset/group/name_of_group/INIT_EXP is created,
252       contatining camera parameters.
253       INITIAL XC    215258.345387
254       INITIAL YC    6911444.022270
255       INITIAL ZC    1101.991120
256       INITIAL OMEGA 0.000000
257       INITIAL PHI   -0.168721
258       INITIAL KAPPA 3.403392
259       VARIANCE XC    5.000000
260       VARIANCE YC    5.000000
261       VARIANCE ZC    5.000000
262       VARIANCE OMEGA 0.000000
263       VARIANCE PHI   0.020153
264       VARIANCE KAPPA 0.017453
265       STATUS (1=OK, 0=NOT OK) 0
266
267       7
268               Compute  ortho-rectification  parameters  from  ground  control
269              points: g.gui.image2target
270
271       This step is to be run in the target location.
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273       The  photo to target transformation parameters, i.e. the "exterior ori‐
274       entation", is computed in Step 7. In  this  interactive  step,  control
275       points  are  marked  on  one or more imagery group files and associated
276       with the known standard (e.g. UTM) and elevation coordinates.   Reason‐
277       able  rectification  results can be obtained with around twelve control
278       points well distributed over the image.   In  this  step,  a  new  file
279       mapset/group/name_of_group/CONTROL_POINTS  is  created,  contatining  a
280       list of pairs of coordinates of ground control points in photo and tar‐
281       get coordinate systems.
282       # Ground Control Points File
283       #
284       # target location: ETRS_33N
285       # target mapset: target_mapset
286       #    source                          target                     status
287       #    east north     height          east     north     height    (1=ok, 0=ignore)
288       #------------------------------     ----------------------    ---------------
289       98.3679932698 906.327649515 0.0    1.0 5.0  100.0             1
290       733.293023813 1329.61100321 0.0    2.0 6.0  100.0             1
291       1292.6317412  1703.76325335 0.0    3.0 7.0  100.0             1
292       1625.54617472 1368.11694482 0.0    4.0 6.0  100.3             1
293       3239.82849913 1390.97403968 0.0    7.4 6.0  100.3             1
294       1570.09788497 2790.06537829 0.0    3.0 11.0 100.0             1
295       Step  7:  Detail  of ground control points matching in an oblique image
296       and terrain model
297
298       8
299               Ortho-rectify imagery group: i.ortho.rectify
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301       This step is to be run in the source location.
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303       Step 8 is used to perform the actual  image  ortho-rectification  after
304       all  of  the transformation parameters have been computed. Ortho-recti‐
305       fied raster files will be created  in  the  target  location  for  each
306       selected  imagery  group file. You may select either the current window
307       in  the  target  location  or  the  minimal  bounding  window  for  the
308       ortho-rectified image.
309       Step  8: Ortho-rectified oblique image As a result, the ortho-rectified
310       raster map is available for visualization and further image analysis.
311

SEE ALSO

313         g.gui.image2target,   g.gui.photo2image,   i.group,   i.ortho.camera,
314       i.ortho.elev, i.ortho.init, i.ortho.rectify, i.ortho.target
315

AUTHOR

317       Mike Baba,  DBA Systems, Inc.
318       GRASS development team, 199?-2017
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SOURCE CODE

321       Available at: i.ortho.photo source code (history)
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323       Main  index | Imagery index | Topics index | Keywords index | Graphical
324       index | Full index
325
326       © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
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330GRASS 7.8.5                                                   i.ortho.photo(1)
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