NAME¶
i.ortho.photo - Menu driver for the photo imagery programs.
KEYWORDS¶
imagery, orthorectify
SYNOPSIS¶
i.ortho.photo
i.ortho.photo help
i.ortho.photo group=
name [--
verbose] [--
quiet]
Parameters:¶
- group=name
-
Name of imagery group for ortho-rectification
DESCRIPTION¶
i.ortho.photo allows the user to ortho-rectify imagery group files. An
imagery group consists of several scanned aerial photographs (raster maps) of
a common area. Imagery groups can be created or modified using the GRASS Image
Processing Program
i.group, or using the first menu option described
below.
i.ortho.photo guides the user through the steps required to
ortho-rectify the raster maps in a single imagery group.
The first menu in
i.ortho.photo provides the user with the following
options:
- Initialization Options:
- 1) Select/Modify imagery group
2) Select/Modify imagery group target
3) Select/Modify target elevation model
4) Select/Modify imagery group camera
- Transformation Parameter Computation:
- 5) Compute image-to-photo transformation parameters
6) Initialize exposure station parameters
7) Compute photo-to-target transformation parameters
- Ortho-rectification Option:
- 8) Ortho-rectify imagery group raster maps
- RETURN to exit
-
>
To ortho-rectify aerial images the user has to follow the menu options step by
step. Generally the user builds a target location containing a projected DEM
and a map reference (topo sheet or other map). Another xy-location will
contain the aerial photo. The entire rectification process is started within
the xy-location. First the target to the projected location has to be set
(i.target), then the image references (fiducial points) will be defined. After
describing the camera parameters, reference points from aerial image to the
topo sheet from the target location will be set. The local elevation will be
taken from the target DEM. Finally the aerial image will be rectified.
The options to follow are described as follows:
- 1. Select/Modify imagery group
-
The current imagery group is display at the top of the previous menu. You
may select another (new or existing) imagery group for the
ortho-rectification program using option (1). After choosing option (1)
you will be prompted for the name of a new or existing imagery group.
Option (1) using the GRASS Image Processing Program i.group, for
creation or modification of imagery groups. For more information on
imagery group creation or modification please the the GRASS manual page
for i.group.
- 2. Select/Modify imagery group target
-
The target location and mapset may be selected or modified using option (2).
After choosing option (2) you will be prompted for the names of the target
location and mapset, where the ortho-rectified raster maps will reside.
The target location is also the location from which the elevation model
(raster map) will be selected -- see option (3). Option (2) uses the GRASS
Image Processing Program i.target, for selection or modification of
the imagery group target location and mapset. For more information on
imagery group selection or modification please the the GRASS manual page
for i.target.
- 3. Select/Modify target elevation model
-
Option (3) allows you to select the raster map from the target location to
be used as the elevation model. The elevation model is required for both
the computation of photo-to-target parameters (option 6) and for the
ortho-rectification of the imagery group files (option 8). The raster map
select for the elevation model should cover the entire area of the image
group to be ortho-rectified. Currently, the elevation model raster map is
expected to be in units of meters. DTED and DEM files are suitable for use
as the elevation model in the ortho-rectification program. After selection
option (3) you will be prompted for the name of the raster map in the
target location that you want to use as the elevation model.
- 4. Select/Modify imagery group camera
-
Using option (4) you may select or create an camera reference file that will
be used with the current imagery group. A camera reference file contains
information on the internal characteristics of the aerial camera, as well
as the geometry of the fiducial or reseau marks. The most important
characteristic of the camera is its focal length. Fiducial or reseau marks
locations are required to compute the scanned image to photo-coordinate
transformation parameter (option 5). For a more detailed description of
option (4) please see the GRASS manual page for
i.photo.camera.
- 5. Compute image-to-photo transformation parameters
-
The scanned image to photo-coordinate transformation parameters are computed
using option (5). In this interactive option you associate scanned
reference points (fiducials, reseau marks, etc.) with their known photo
coordinates from the camera reference file. Complete documentation for
this option is available under the manual entry
i.photo.2image.
- 6. Initialize exposure station parameters
-
If option (6) is selected, initial camera exposure station parameters and
initial variances may be selected or modified. Complete documentation for
this option is available under the manual entry i.photo.init.
- 7. Compute photo-to-target transformation parameters
-
The photo to target transformation parameters are compute using option (7).
Here control points are marked on one or more imagery group files and
associated with there known standard (e.g. UTM) and elevation coordinates.
Complete documentation for this option is available under the manual entry
i.photo.2target.
- 8. Ortho-photo imagery group files
-
Option (8) is used to perform the actual image ortho-rectification after all
of the transformation parameters have been computed. Ortho-rectified
raster files will be created in the target location for each selected
imagery group file. You may select either the current window in the target
location or the minimal bounding window for the ortho-rectified image.
Complete documentation for this option is available under the manual entry
i.photo.rectify.
NOTES¶
i.ortho.photo currently requires the elevation model to be in meters, and
the target location to be a standard (e.g. UTM) coordinate system.
REFERENCES¶
-
Wolf, P.R. (1983): Elements of Photogrammetry, With Air Photo
Interpretation and Remote Sensing. 2nd ed. McGraw Hill, 562 pages
-
Rocchini, D., Metz, M., Frigeri, A., Delucchi, L., Marcantonio, M.,
Neteler, M. (2012). Robust rectification of aerial photographs in an open
source environment. Computers & Geosciences 39 (2): 145-151.
SEE ALSO¶
i.photo.camera,
i.photo.2image,
i.photo.2target,
i.photo.init,
i.photo.rectify
AUTHOR¶
Mike Baba, DBA Systems, Inc.
Updated rectification and elevation map to FP 1/2002 Markus Neteler
Last changed: $Date: 2012-01-08 22:48:21 +0100 (Sun, 08 Jan 2012) $
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