[Gdal-dev] gdal newbie-merge geotiff images
Ken Boss
Ken.Boss at dnr.state.mn.us
Thu Nov 16 10:20:41 EST 2006
Hello Izzy--
If using gdal_merge.py, you can simply specify the nodata value on the
command line with the -n option. So if those black background pixels
are all zeroes, just add -n 0 to your command line.
I would point out, though, that tiff images are limited to a maximum of
4 GB, and that gdal_merge.py reads entire input images into memory, so
you may be constrained by one or both of these.
gdalwarp is likely the better option. There you can use the -srcnodata
option to specify the nodata value(s) to be ignored from the input
images. If you're working with a limited number of images, you might
obtain the bounding boxes for the images using the gdalinfo utility.
HTH,
--Ken
>>> Izzy <izzybitsie at gmail.com> 11/15/2006 2:56:47 PM >>>
I am trying to stitch together several satellite geotiff images to
obtain a
world image.
The individual images display the satellite picture with black areas on
the
sides of the picture itself.
So, when merging the images using gdal_merge.py some pictures are
hidden
underneath the black portion of neighbour images. Couldn't use -pct
option
due to images characteristics. Pls. see below the color tables in the
input
images.
The original images do not have a no-data value assigned to pixels to
avoid
copying them.
So, for now my only option would be to crop the black areas that are
always
the same size around the image. I am trying to do this using gdalwarp,
but
I still can't figure out how to obtain the georeferenced box to be
used
along with -projwin option.
BTW. I haven't been able to see these images using OpenEV although I
can
see them with ImageMagick. Any idea on what I may be doing wrong in
OpenEV? I do need to run openev with the "-h" option since it quits on
me
when opening an image otherwise. I have been able to see other
geotiffs
downloaded from Internet in openev though.
Any help on how to cut the black areas is appreciated.
Some info on 2 of the input images and the output images:
Input number 1
Origin = (45.833333,75.000000)
Pixel Size = (0.08055556,-0.08055556)
Metadata:
AREA_OR_POINT=Area
Corner Coordinates:
Upper Left ( 45.8333333, 75.0000000) (142d30'0.03"E, 0d 0'0.04"N)
Lower Left ( 45.8333333, -70.0000000) (142d30'0.03"E, 0d 0'0.04"S)
Upper Right ( 239.167, 75.000) (142d30'0.14"E, 0d 0'0.04"N)
Lower Right ( 239.167, -70.000) (142d30'0.14"E, 0d 0'0.04"S)
Center ( 142.5000000, 2.5000000) (142d30'0.08"E, 0d 0'0.00"N)
Band 1 Block=2400x3 Type=Byte, ColorInterp=Palette
Color Table (RGB with 256 entries)
0: 0,0,0,255
1: 0,0,0,255
2: 0,0,0,255
3: 0,0,0,255
4: 0,0,0,255
5: 0,0,0,255
6: 0,0,0,255
7: 0,0,0,255
8: 0,0,0,255
9: 0,0,0,255
10: 0,0,0,255
11: 0,0,0,255
12: 0,0,0,255
13: 0,0,0,255
14: 0,0,0,255
15: 0,0,0,255
16: 0,0,0,255
17: 0,0,0,255
18: 0,0,0,255
19: 0,0,0,255
20: 0,0,0,255
...............................................................rest of
values in color table look the same
Input number 2
Driver: GTiff/GeoTIFF
Size is 2400, 1800
Coordinate System is:
PROJCS["unnamed",
GEOGCS["unnamed",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.2572235629972,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT[,0.0174532925199433]],
PROJECTION["Equirectangular"],
PARAMETER["latitude_of_origin",2.5],
PARAMETER["central_meridian",-155],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["degree",0.01745329251994328,
AUTHORITY["EPSG","9102"]]]
Origin = (-251.537842,74.963768)
Pixel Size = (0.08051530,-0.08051530)
Metadata:
AREA_OR_POINT=Area
Corner Coordinates:
Upper Left ( -251.538, 74.964) (155d 0'0.14"W, 0d 0'0.04"N)
Lower Left ( -251.538, -69.964) (155d 0'0.14"W, 0d 0'0.04"S)
Upper Right ( -58.3011272, 74.9637681) (155d 0'0.03"W, 0d 0'0.04"N)
Lower Right ( -58.3011272, -69.9637681) (155d 0'0.03"W, 0d 0'0.04"S)
Center (-154.9194847, 2.5000000) (155d 0'0.09"W, 0d 0'0.00"N)
Band 1 Block=2400x3 Type=Byte, ColorInterp=Palette
Color Table (RGB with 256 entries)
0: 0,0,0,255
1: 0,0,0,255
2: 0,0,0,255
3: 0,0,0,255
4: 0,0,0,255
5: 0,0,0,255
6: 0,0,0,255
7: 0,0,0,255
8: 0,0,0,255
9: 0,0,0,255
10: 0,0,0,255
11: 0,0,0,255
12: 0,0,0,255
13: 0,0,0,255
14: 0,0,0,255
15: 0,0,0,255
16: 0,0,0,255
17: 0,0,0,255
18: 0,0,0,255
19: 0,0,0,255
20: 0,0,0,255
.................................................................. rest
of
values in color table look the same
Output from gdal_merge.py -o <outpiut> <Input number 1> <Input number
2>
Driver: GTiff/GeoTIFF
Size is 6067, 1800
Coordinate System is:
PROJCS["unnamed",
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.2572235629972,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]],
PROJECTION["Equirectangular"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",135],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["unknown",1]]
Origin = (-243.264249,69.948187)
Pixel Size = (0.07772021,-0.07772021)
Metadata:
AREA_OR_POINT=Area
Corner Coordinates:
Upper Left ( -243.264, 69.948) (134d59'52.13"E, 0d 0'2.28"N)
Lower Left ( -243.264, -69.948) (134d59'52.13"E, 0d 0'2.28"S)
Upper Right ( 228.264, 69.948) (135d 0'7.38"E, 0d 0'2.28"N)
Lower Right ( 228.264, -69.948) (135d 0'7.38"E, 0d 0'2.28"S)
Center ( -7.5000000, -0.0000000) (134d59'59.76"E, 0d 0'0.00"S)
Band 1 Block=6067x1 Type=Byte, ColorInterp=Gray
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