Hi Even,<br><br>Thanks for replying. I am currently using gdal version <a href="http://1.5.1.">1.5.1.</a> I realised previously the gdal issue i had with building overviews was because I used external libtiff library. (probably version 3.8). After switching to using the internally built libtiff library that comes with gdal, everything is working well.<br>
<br>Thanks alot<br>Heng Hock<br><br><br><div class="gmail_quote">On Wed, Jun 4, 2008 at 1:48 AM, Even Rouault <<a href="mailto:even.rouault@mines-paris.org" target="_blank">even.rouault@mines-paris.org</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi,<br>
<br>
You have to more specific on which GDAL version you are using, whether it is<br>
compiled using internal or external libtiff, the properties of your TIFF<br>
file. If external libtiff, which libtiff version it is, etc etc. But<br>
generally, there's no incompatibility between Linux and overview building.<br>
The same combination of GDAL + libtiff versions should yield the same results<br>
on both Windows and Linux.<br>
<br>
If using an "old" GDAL and/or libtiff version, you should also consider<br>
upgrading to latest GDAL and compiling it with internal libtiff support. For<br>
your information, there were problems with older GDAL&libtiff versions when<br>
building overviews on TIFF files in compressed formats like LZW or JPEG that<br>
have been solved since then.<br>
<br>
Le Tuesday 03 June 2008 11:33:50 lee heng hock, vous avez écrit :<br>
<div><div></div><div>> hi,<br>
><br>
> I attempted to build overviews for .tiff files on Linux and windows. For<br>
> the windows version, building of overviews worked fine. But on linux, I<br>
> have this error message:<br>
><br>
> "ERROR 1: IReadBlock failed at X offset ... "<br>
><br>
> I did a google search and seems to me that this problem is inherent in<br>
> gdal. Is this problem existent only in Linux but not on windows?<br>
><br>
> Regards<br>
> Heng Hock<br>
><br>
> On Tue, Jun 3, 2008 at 12:00 AM, <<a href="mailto:gdal-dev-request@lists.osgeo.org" target="_blank">gdal-dev-request@lists.osgeo.org</a>> wrote:<br>
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> > 1. Re: Converting between datum (Bryan Keith)<br>
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> ><br>
> > ----------------------------------------------------------------------<br>
> ><br>
> > Message: 1<br>
> > Date: Mon, 2 Jun 2008 08:37:57 -0600 (MDT)<br>
> > From: "Bryan Keith" <<a href="mailto:bryan@ideotrope.org" target="_blank">bryan@ideotrope.org</a>><br>
> > Subject: Re: [gdal-dev] Converting between datum<br>
> > To: "Andreas Theofilu" <<a href="mailto:andreas@theosys.at" target="_blank">andreas@theosys.at</a>><br>
> > Cc: GDAL list <<a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a>><br>
> > Message-ID: <<a href="mailto:2326.64.78.232.178.1212417477.squirrel@ideotrope.org" target="_blank">2326.64.78.232.178.1212417477.squirrel@ideotrope.org</a>><br>
> > Content-Type: text/plain;charset=iso-8859-1<br>
> ><br>
> > > Am Sonntag, 1. Juni 2008 14:01:53 schrieben Sie:<br>
> > ><br>
> > > Frank, thanks for that hint. It seems to work, but:<br>
> > >> So, try changing your DataWindow definition to:<br>
> > >><br>
> > >> <DataWindow><br>
> > >> <UpperLeftX>617400</UpperLeftX><br>
> > >> <UpperLeftY>481865</UpperLeftY><br>
> > >> <LowerRightX>626560</LowerRightX><br>
> > >> <LowerRightY>480365</LowerRightY><br>
> > >> <SizeX>916</SizeX><br>
> > >> <SizeY>150</SizeY><br>
> > >> </DataWindow><br>
> > ><br>
> > > call me stupid, but I can't figure out how you calculated these values.<br>
> > > Allthough I know what square pixel means, I don't know how I can<br>
> ><br>
> > calculate<br>
> ><br>
> > > them. Could you or anybody else point me to a page where I may find a<br>
> > > documentation on how to do that?<br>
> ><br>
> > Andreas,<br>
> ><br>
> > Here you see how to calculate the cellsize from the given numbers:<br>
> > >>> 481865 - 480365<br>
> ><br>
> > 1500<br>
> ><br>
> > >>> _ / 150.<br>
> ><br>
> > 10.0<br>
> ><br>
> > >>> 626560 - 617400<br>
> ><br>
> > 9160<br>
> ><br>
> > >>> _ / 916.<br>
> ><br>
> > 10.0<br>
> ><br>
> > So Frank made square cells size 10.0. In the other direction you need to<br>
> > slightly increase your extent and then calculate the number of pixels in<br>
> > x and y so that you get square cells.<br>
> ><br>
> > Bryan<br>
> ><br>
> > > --<br>
> > > Andreas Theofilu<br>
> > > TheoSys - Software Systems and Solutions<br>
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> > > Tel.: +43 676 / 786 53 89<br>
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<br>
<br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>Regards<br>Heng Hock