1i.ortho.photo(1) GRASS GIS User's Manual i.ortho.photo(1)
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6 i.ortho.photo - Menu driver for the photo imagery programs.
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9 imagery, orthorectify, geometry
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12 i.ortho.photo
13 i.ortho.photo --help
14 i.ortho.photo group=name productname=string [--help] [--verbose]
15 [--quiet] [--ui]
16 Flags:
18 --help
19 Print usage summary
20 --verbose
22 Verbose module output
23 --quiet
25 Quiet module output
26 --ui
28 Force launching GUI dialog
29 Parameters:
31 group=name [required]
32 Name of imagery group for ortho-rectification
33 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
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.
56 • Initialization Options
58 • Create/Modify imagery group to be orthorectified: i.group
60 • Select/Modify target location and mapset for orthorectifica‐
62 tion: i.ortho.target
63 • Select/Modify target elevation model used for orthorectifica‐
65 tion: i.ortho.elev
66 • Create/Modify camera file of imagery group: i.ortho.camera
68 • Transformation Parameters Computation
70 • Compute image-to-photo transformation: g.gui.photo2image
72 • Initialize parameters of camera: i.ortho.init
74 • Compute ortho-rectification parameters from ground control
76 points: g.gui.image2target
77 • Ortho-rectification
79 • Ortho-rectify imagery group: i.ortho.rectify
81 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
91 Five groups of input parameters are required for ortho-rectification:
92 • Aerial image (images),
94 • 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,
99 • Reference surface, i.e. digital elevation model in the target
101 coordinate system used to normalize the terrain undulation,
102 • Topographic reference map used to find corresponding ground
104 control points and/or,
105 • Coordinates of ground control points in the target coordinate
107 system.
108 Example of an input oblique image in a source location
109 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.
113 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 The steps to follow are described below:
121 1 Create/Modify imagery group to be orthorectified: i.group
123 This step is to be run in the source location.
125 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 2 Select/Modify target location and mapset for orthorectification:
138 i.ortho.target
139 This step is to be run in the source location.
141 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
151 3 Select/Modify target elevation model used for orthorectifica‐
153 tion: i.ortho.elev
154 This step is to be run in the source location.
156 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 lo‐
165 cation that you want to use as the elevation model. As a result of this
166 step, a new file mapset/group/name_of_group/ELEVATION is created conta‐
167 tining 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)
174 4
176 Create/Modify camera file of imagery group: i.ortho.camera
177 This step is to be run in the source location.
179 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 re‐
185 seau marks locations are required to compute the scanned image to photo
186 coordinate transformation parameter (Step 5). Two new files are created
187 in this step: a file mapset/group/name_of_group/CAMERA, contatining the
188 name of the reference camera and a file mapset/camera/name_of_refer‐
189 ence, 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 5
202 Compute image-to-photo transformation: g.gui.photo2image
203 This step is to be run in the source location.
205 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
225 6
227 Initialize parameters of camera: i.ortho.init
228 This step is to be run in the source location.
230 In Step 6, initial camera exposure station parameters and initial vari‐
232 ances may be selected or modified.
233 • X: East aircraft position;
235 • Y: North aircraft position;
237 • Z: Flight heigh above surface;
239 • Omega (pitch): Raising or lowering of the aircraft’s front
241 (turning around the wings’ axis);
242 • Phi (roll): Raising or lowering of the wings (turning around
244 the aircraft’s axis);
245 • 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 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 7
268 Compute ortho-rectification parameters from ground control
269 points: g.gui.image2target
270 This step is to be run in the target location.
272 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 8
299 Ortho-rectify imagery group: i.ortho.rectify
300 This step is to be run in the source location.
302 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 se‐
306 lected imagery group file. You may select either the current window in
307 the target location or the minimal bounding window for the ortho-recti‐
308 fied 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
313 Wolf P.R. (1983). Elements of Photogrammetry: With Air Photo Interpre‐
314 tation and Remote Sensing McGraw Hill Higher Education ISBN-10:
315 0070713456, ISBN-13: 978-0070713451
316
318 g.gui.image2target, g.gui.photo2image, i.group, i.ortho.camera, i.or‐
319 tho.elev, i.ortho.init, i.ortho.rectify, i.ortho.target
320
322 Mike Baba, DBA Systems, Inc.
323 GRASS development team, 199?-2017
324
326 Available at: i.ortho.photo source code (history)
327 Accessed: Saturday Jan 21 20:40:49 2023
329 Main index | Imagery index | Topics index | Keywords index | Graphical
331 index | Full index
332 © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
334GRASS 8.2.1 i.ortho.photo(1)