hi at all,
We're studing Orthorectfication solutions inside the GFOSS world. We need to know and share common problems.
In the GRASS world, we found i.ortho.photo, but it's not clear for us what algorithm is used by this command (GCP, RPC, others...). Do you have experience?
Our question is also to users who found different solutions inside GFOSS world, OSSIM for example. Do you have experience?
Thanks for the help,
Gino Pirelli
http://www.riade.net
http://www.acsys.it
Hi all,
I have a series of georeferenced aerial photographs as 8 bit tiff files.
I have imported these into Grass using r.in.gdal and can visualize them with d.rast
Now I want to patch them together in order to use them in NVIZ as color raster.
Because the images are 8 bit indexed colours I can't use r.patch to patch the images together in one go.
I suppose I have to split the images first into red, green and blue bands, patch each band together with r.patch, and combine the patched red, green and blue bands again.
I can't find the Grass command to split the raster image in to red, green and blue rasters. How do I do this in Grass? Is there another way of achieving a patched image of the aerial photographs?
Any help is greatly appreciated,
thanks,
-Jeroen.
On Wed, 12 Apr 2006 17:27:34 +0200
Jeroen Wortel <j.wortel@wanadoo.nl> wrote:
I have a series of georeferenced aerial photographs as 8 bit tiff
files. I have imported these into Grass using r.in.gdal and can
visualize them with d.rast
Now I want to patch them together in order to use them in NVIZ as
color raster.Because the images are 8 bit indexed colours I can't use r.patch to
patch the images together in one go.
I suppose I have to split the images first into red, green and blue
bands, patch each band together with r.patch, and combine the patched
red, green and blue bands again.I can't find the Grass command to split the raster image in to red,
green and blue rasters. How do I do this in Grass?
Please read GREY SCALE EQUIVALENTS AND COLOR SEPARATES section in
r.mapcalc manual.
Hope this helps.
Maciek
--------------------
W polskim Internecie s? setki milion?w stron. My przekazujemy Tobie tylko najlepsze z nich!
http://katalog.panoramainternetu.pl/
Jeroen Wortel wrote:
I have a series of georeferenced aerial photographs as 8 bit tiff files.
I have imported these into Grass using r.in.gdal and can visualize
them with d.rast
Now I want to patch them together in order to use them in NVIZ as color raster.Because the images are 8 bit indexed colours I can't use r.patch to
patch the images together in one go.
I suppose I have to split the images first into red, green and blue
bands, patch each band together with r.patch, and combine the patched
red, green and blue bands again.I can't find the Grass command to split the raster image in to red,
green and blue rasters. How do I do this in Grass?
r.mapcalc 'map.r = r#map ; map.g = g#map ; map.b = b#map'
Is there another way of achieving a patched image of the aerial
photographs?
You could convert the separate R/G/B maps to a single composite colour
map before patching, although this will degrade the colour resolution
(24-bpp composite images aren't practical).
You could convert the images to either RGB or to a common palette
using image-processing software prior to importing. If you import an
RGB image with r.in.gdal, it will import it as separate R/G/B
channels.
The ideal solution would be to get hold of the original RGB images.
--
Glynn Clements <glynn@gclements.plus.com>
On Wed, Apr 12, 2006 at 04:52:16PM +0200, Luigi Pirelli wrote:
hi at all,
We're studing Orthorectfication solutions inside the GFOSS world. We need
to know and share common problems.In the GRASS world, we found i.ortho.photo, but it's not clear for us what
algorithm is used by this command (GCP, RPC, others...). Do you have
experience?
The i.ortho.photo implementation follows the algorithms
described in this book:
Elements of Photogrammetry, With Air Photo Interpretation and
Remote Sensing by Paul R. Wolf, 562 pages
Publisher: McGraw Hill Text; 2nd edition (January 1983)
You can still find it for a few Euros/Dollars.
In GRASS 5, there is a src/libes/image3/ library which is
an extended version including LANDSAT ortho-rectification but
it was never completed (as far as I know). Related commands
are i.points3 and i.rectify3 in GRASS 5. It would be great
if capable programmer(s) make this code (treasure?) ready
for GRASS 6.
Best
Markus
thanks a lot Markus
Bye Ginetto
Markus Neteler wrote:
On Wed, Apr 12, 2006 at 04:52:16PM +0200, Luigi Pirelli wrote:
hi at all,
We're studing Orthorectfication solutions inside the GFOSS world. We need to know and share common problems.
In the GRASS world, we found i.ortho.photo, but it's not clear for us what algorithm is used by this command (GCP, RPC, others...). Do you have experience?
The i.ortho.photo implementation follows the algorithms
described in this book:Elements of Photogrammetry, With Air Photo Interpretation and
Remote Sensing by Paul R. Wolf, 562 pages
Publisher: McGraw Hill Text; 2nd edition (January 1983)You can still find it for a few Euros/Dollars.
In GRASS 5, there is a src/libes/image3/ library which is
an extended version including LANDSAT ortho-rectification but
it was never completed (as far as I know). Related commands
are i.points3 and i.rectify3 in GRASS 5. It would be great
if capable programmer(s) make this code (treasure?) ready
for GRASS 6.Best
Markus