First of all, i'm beginner with GRASS usage.
I have a set of aerian pictures which followed each others, with about 60% of
common coverage. My goal is to obtain a unique color picture orthorectified and
georeferenced.
1°) I've scanned my aerian pictures to obtain tiff files. I've imported them in
grass using r.in.gdal, so i've 3 rasters files (RGB) by aerian pictures.
I've done the orthorectify process, picture by picture, working with the 3
rasters RGB of one picture at a time.
Is it the good way to do it, or is there a faster way to do it?
isn't it better to gather the 3 RGB rasters using r.composite and then going on
the orthorectification process on this picture, or on a group of composite
pictures belonging to my set of aerian pictures?
2°) Once the orthorectify process is done, i've got many orthorectified and
georeferenced rasters.
So i've used r.composite to gather RGB rasters of a same picture.
then, I've got many composite rasters, orthorectified and georeferenced, each
raster having part of itself in common with another raster (common coverage of
60%) and each raster having uninteresting informations (fiducial marks, black
strip surrounding the picture itself, aerian picture indicators as focal, ...)
that needs to be suppressed.
How can i do now to gather all these rasters to have a single accurate
orthorectifed and georeferenced raster without the uninteresting informations,
and taking advantage of the commun coverage of the rasters to improve the
quality of this unique raster, for exemple in attenuating the errors due to the
camera on the edge of each aerian picture.
I've thought to use i.image.mosaic or r.patch, but i don't know what to do with
it....
Can i do what i wwant using Grass? or do i need another software? if so, do you
know open source software coping with my needs
3°) I work on windows server (w2000 server SP4), with a Pentium IV 2.8 GHz, 1 Go
RAM, so i use cygwin and "d.m" interface
I use grass version 6.0.0
Is it normal that display process, and more over pointing with mouse or zoom
processes were some time very very long, freezing completely the server...
On Fri, 28 Apr 2006 04:29:29 +0200
olivier.faivre@free.fr wrote:
<snip>
How can i do now to gather all these rasters
to have a single accurate orthorectifed and georeferenced raster
without the uninteresting informations, and taking advantage of the
commun coverage of the rasters to improve the quality of this unique
raster, for exemple in attenuating the errors due to the camera on
the edge of each aerian picture.
I think first mask out the unwanted pieces of your image:
I've thought to use i.image.mosaic
or r.patch, but i don't know what to do with it....
Now r.patch should be easier. ?.
Can i do what i wwant using Grass? or do i need another software? if
so, do you know open source software coping with my needs
3°) I work on windows server (w2000 server SP4), with a Pentium IV
2.8 GHz, 1 Go RAM, so i use cygwin and "d.m" interface
I use grass version 6.0.0
Is it normal that display process, and more over pointing with mouse
or zoom processes were some time very very long, freezing completely
the server...
6.0.0 has a bug in X displays that consumes 100% on mouse ops. It is
fixed for 6.1 CVS.
Maciek
--------------------
W polskim Internecie s± setki milionów stron. My przekazujemy Tobie tylko najlepsze z nich! http://katalog.panoramainternetu.pl/
I have a set of aerian pictures which followed each others, with about
60% of common coverage. My goal is to obtain a unique color picture
orthorectified and georeferenced.
1°) I've scanned my aerian pictures to obtain tiff files. I've
imported them in grass using r.in.gdal, so i've 3 rasters files (RGB)
by aerian pictures. I've done the orthorectify process, picture by
picture, working with the 3 rasters RGB of one picture at a time.
Is it the good way to do it, or is there a faster way to do it?
isn't it better to gather the 3 RGB rasters using r.composite and then
going on the orthorectification process on this picture, or on a group
of composite pictures belonging to my set of aerian pictures?
Yes, i.group will help you rectify all three images with just one set of
ground control points and is the best thing to use.
r.composite will reduce each band to 32 values from the original 256,
so you lose information when you use it. It is better to keep all
three channels and display with the d.rgb module or the ps.map equivalent.
2°) Once the orthorectify process is done, i've got many
orthorectified and georeferenced rasters.
So i've used r.composite to gather RGB rasters of a same picture.
then, I've got many composite rasters, orthorectified and
georeferenced, each raster having part of itself in common with
another raster (common coverage of 60%) and each raster having
uninteresting informations (fiducial marks, black strip surrounding
the picture itself, aerian picture indicators as focal, ...) that
needs to be suppressed. How can i do now to gather all these rasters
to have a single accurate orthorectifed and georeferenced raster
without the uninteresting informations, and taking advantage of the
commun coverage of the rasters to improve the quality of this unique
raster, for exemple in attenuating the errors due to the camera on the
edge of each aerian picture. I've thought to use i.image.mosaic or
r.patch, but i don't know what to do with it....
Can i do what i wwant using Grass? or do i need another software? if
so, do you know open source software coping with my needs
(as Maciek already has commented)
r.mapcalc to make a dynamic MASK based on row() and col() values, to
only keep the middle of each image, then r.patch? (r.patch works in
order of input maps)