[gdal-dev] Enquiry regarding building of overviews

[Even Rouault]

Hi,

You have to more specific on which GDAL version you are using, whether it is 
compiled using internal or external libtiff, the properties of your TIFF 
file. If external libtiff, which libtiff version it is, etc etc. But 
generally, there's no incompatibility between Linux and overview building. 
The same combination of GDAL + libtiff versions should yield the same results 
on both Windows and Linux. 

If using an "old" GDAL and/or libtiff version, you should also consider 
upgrading to latest GDAL and compiling it with internal libtiff support. For 
your information, there were problems with older GDAL&libtiff versions when 
building overviews on TIFF files in compressed formats like LZW or JPEG that 
have been solved since then.

Le Tuesday 03 June 2008 11:33:50 lee heng hock, vous avez écrit :
> hi,
>
> I attempted to build overviews for .tiff files on Linux and windows. For
> the windows version, building of overviews worked fine. But on linux, I
> have this error message:
>
> "ERROR 1: IReadBlock failed at X offset ... "
>
> I did a google search and seems to me that this problem is inherent in
> gdal. Is this problem existent only in Linux but not on windows?
>
> Regards
> Heng Hock
>
> On Tue, Jun 3, 2008 at 12:00 AM, <gdal-dev-request at lists.osgeo.org> wrote:
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> > Today's Topics:
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> >   1. Re: Converting between datum (Bryan Keith)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Mon, 2 Jun 2008 08:37:57 -0600 (MDT)
> > From: "Bryan Keith" <bryan at ideotrope.org>
> > Subject: Re: [gdal-dev] Converting between datum
> > To: "Andreas Theofilu" <andreas at theosys.at>
> > Cc: GDAL list <gdal-dev at lists.osgeo.org>
> > Message-ID: <2326.64.78.232.178.1212417477.squirrel at ideotrope.org>
> > Content-Type: text/plain;charset=iso-8859-1
> >
> > > Am Sonntag, 1. Juni 2008 14:01:53 schrieben Sie:
> > >
> > > Frank, thanks for that hint. It seems to work, but:
> > >> So, try changing your DataWindow definition to:
> > >>
> > >>     <DataWindow>
> > >>        <UpperLeftX>617400</UpperLeftX>
> > >>        <UpperLeftY>481865</UpperLeftY>
> > >>        <LowerRightX>626560</LowerRightX>
> > >>        <LowerRightY>480365</LowerRightY>
> > >>        <SizeX>916</SizeX>
> > >>        <SizeY>150</SizeY>
> > >>     </DataWindow>
> > >
> > > call me stupid, but I can't figure out how you calculated these values.
> > > Allthough I know what square pixel means, I don't know how I can
> >
> > calculate
> >
> > > them. Could you or anybody else point me to a page where I may find a
> > > documentation on how to do that?
> >
> > Andreas,
> >
> > Here you see how to calculate the cellsize from the given numbers:
> > >>> 481865 - 480365
> >
> > 1500
> >
> > >>> _ / 150.
> >
> > 10.0
> >
> > >>> 626560 - 617400
> >
> > 9160
> >
> > >>> _ / 916.
> >
> > 10.0
> >
> > So Frank made square cells size 10.0.  In the other direction you need to
> > slightly increase your extent and then calculate the number of pixels in
> > x and y so that you get square cells.
> >
> > Bryan
> >
> > > --
> > > Andreas Theofilu
> > > TheoSys - Software Systems and Solutions
> > > http://www.theosys.at
> > > Tel.: +43 676 / 786 53 89
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> > End of gdal-dev Digest, Vol 49, Issue 4
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