[osg-users] Problem with combining texture maps.

Wojciech Lewandowski lewandowski at ai.com.pl
Thu Oct 4 14:23:32 PDT 2007

Pictures you sent look like GTOPO30 elevation tile thumbnails. They don't
seem to be georefernced. Which means you need to define the mapping between
database coordinates and image pixels.

 If you want to create flat non georeferenced database you may do it as
described in the osgDem wiki page: using options -xx -yy. But you will also
need some more options to indicate image origins (--xy, --yx etc).
Unfortunately these are not documented (you would need to look at the
source) .
In practice there are more options than wiki page shows. Running --help will
display all of them.

It seems that similar functionality may give the --range option. Just
precede each -t image call with  --range Xmin Xmax Ymin Ymax. This will
define world extents of the next image you load with -t option.

I don't have the osgDem at home. I cannot test this but I would try to
define extents with following options:
--range -180 -140 40 90  -t W180N90.tif
--range -140 -100 40 90  -t W140N90.tif

There is one catch, I am not sure if --range was already present in all
osgDEM versions. If you don't find it,  try VPB or ultimate method: load
these two into some image editor, merge them and use single -t option with
merged image.


PS1: On a side note: option -t treats these as colour channels not elevation
are your sure you don't want to use -d option instead of -t.

PS2: osgDem was superceded by Virtual Planet Builder VPB project. You may
check it out. For sure it will have --range option.

-----Original Message-----
From: om [mailto:omkaranathan at darshan3d.com]
Sent: Thursday, October 04, 2007 9:50 PM
To: lewandowski at ai.com.pl; OpenSceneGraph Users
Subject: Re: [osg-users] Problem with combining texture maps.

Wojciech Lewandowski wrote:

>If you have copied the same command as you invoked,  thats because you use
>osgdem -t option twice with the same W180N90.tif file. ;-).
>If you did a mistake in the email and not in real command, and actually use
>two different tiffs then it may mean that your tiffs are not georeferenced
>(GeoTiff) and osgDem does assume they cover the same range. You may need to
>use other osgDem options to define word ranges this tiffs correspond to ...
>Run osgDem --help  for the list of options.
>-----Original Message-----
>From: osg-users-bounces at lists.openscenegraph.org
>[mailto:osg-users-bounces at lists.openscenegraph.org]On Behalf Of om
>Sent: Thursday, October 04, 2007 8:53 PM
>To: OpenSceneGraph Users
>Subject: [osg-users] Problem with combining texture maps.
>I tried to combine two texture maps with the following command line
>script using osgdem.
>osgdem -t W180N90.tif  -t W180N90.tif -l 1 -a output.osga
>output.osga shows the second texture map only. It'll be great if
>somebody can enlighten me on where it is going wrong.
>I can send the texture maps if required
>osg-users mailing list
>osg-users at lists.openscenegraph.org
>osg-users mailing list
>osg-users at lists.openscenegraph.org
sorry the similarity in names was a mistake in the mail...
Could you please suggest the option to be used from osgdem as I am
unable to find it out. :-(
I am sending the texture maps also for ur reference.


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