Hi to all,
I'm trying to use GRASS 6.4 (installed on UBUNTU) to realize a system to automate the orthorectification process.
I have a group of little images (chip of 256x256 pixel) that I want to use to orthorectify an image.
Can grass use the little chip to create the RPC polynomial without any external action? I try i.points.auto, but I must set the GCP manually...
Thank you
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Hi,
the GCPs are located in each image at known locations, you can create
necessary files in a batch script:
- you have to create the group for each image (i.group)
- you have to set the target and ref files for the group (i.target)
- you have to create the POINTS file - manually
try to rectify one image by hand and then see grassdata/LOCATION/MAPSET/group/GROUP/*
however, if the position of GCPs is unknown to you, I'm affraid, you
have to do it by hand
jachym
On Wed, Mar 25, 2009 at 03:04:43AM -0700, Petrone Orlando Mauro wrote:
Hi to all,
I'm trying to use GRASS 6.4 (installed on UBUNTU) to realize a system to automate the orthorectification process.
I have a group of little images (chip of 256x256 pixel) that I want to use to orthorectify an image.
Can grass use the little chip to create the RPC polynomial without any external action? I try i.points.auto, but I must set the GCP manually...
Thank you
--
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Jachym Cepicky
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On Thu, Mar 26, 2009 at 7:57 AM, Jachym Cepicky
<jachym.cepicky@gmail.com> wrote:
...
however, if the position of GCPs is unknown to you, I'm affraid, you
have to do it by hand
Maybe you can hack i.points.auto to
http://grass.osgeo.org/wiki/Image_processing#Geocoding
"seed" it with a priori knowledge or you start with very rough resolution
and then increase it in a cycle to get more precise chips. This would
require source code modification of course to take out the interactive
part (which is obsolete for GRASS 7 anyway and needs to be rewritten).
Markus
I have this little chip (256x256px) that are taken from an orthorectified image, so I have all the coordinate for all them. I want to use this little image to orthorectify a new image. What are the right step for this?
Mauro
Jachym Cepicky ha scritto:
however, if the position of GCPs is unknown to you, I'm affraid, you
have to do it by hand
I have this little chip (256x256px) that are taken from an orthorectified image, so I have all the coordinate for all them. I want to use this little image to orthorectify a new image. What are the right step for this?
Mauro
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On Thu, Mar 26, 2009 at 04:58:25AM -0700, Petrone Orlando Mauro wrote:
I have this little chip (256x256px) that are taken from an orthorectified image, so I have all the coordinate for all them. I want to use this little image to orthorectify a new image. What are the right step for this?
Mauro
write a script, which would assing source and target coordinates
automatically (creating the POINTS file) and call i.group, i.target &&
i.rectify at the end
jachym
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Jachym Cepicky
e-mail: jachym.cepicky gmail com
URL: http://les-ejk.cz
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Key fingerprint: 0C6D 0EAE 76BD 506C F299 ED8A C8AB 74B8 08D4 E08F