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02.02.2012 18:10, Andrea Peri пишет:
<blockquote
cite="mid:CABqTJk8qUXM9wjzxQbFzCYxLtYr2k=mh2bbCWrZtriFQZH7L9A@mail.gmail.com"
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<br>
<div class="gmail_quote">2012/2/2 Even Rouault <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:even.rouault@mines-paris.org">even.rouault@mines-paris.org</a>></span><br>
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Selon Andrea Peri <<a moz-do-not-send="true"
href="mailto:aperi2007@gmail.com">aperi2007@gmail.com</a>>:<br>
<div class="im"><br>
> Hi,<br>
><br>
> Unfortunately I was unable to test with GDB.<br>
> My skill was not enough :(<br>
<br>
</div>
Well, provided you have gdb installed, it is "just" a matter
of :<br>
<br>
1) "gdb qgis"<br>
2) in the gdb console, type "run" and validate<br>
3) when qgis is slow, switch to the console with gdb and hit
Ctrl+C<br>
4) in the gdb console, type "bt" (for backtrace)and validate,
and then it can<br>
give some interesting information<br>
5) to go on qgis execution, type "c" (continue) and validate<br>
6) you can go to 3) again<br>
<div class="im"><br>
</div>
</blockquote>
<div><br>
thx, I try it .<br>
<br>
</div>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt
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<div class="im">
><br>
> However I try other ways</div>
</blockquote>
<div>> <br>
</div>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt
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<div class="im">.....</div>
</blockquote>
<div> </div>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt
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<div class="im">> So qgis necessary must open all the
raster to understand what raster is on<br>
> the visible portion on the canvas.<br>
<br>
</div>
No, what you show above is sufficient to defer the loading of
individual tiles,<br>
until they are really necessary.<br>
<br>
What I suspect is that your vrt has no associated overviews,
so when you open<br>
qgis, it will try to display the overall coverage of the
raster, which then will<br>
require to open each tile.<br>
<br>
Try "gdaladdo your.vrt 2 4 8 16 32"<br>
<div class="im"><br>
</div>
</blockquote>
<div><br>
I try to create the overview, but it is really sloow .<br>
After 1hours is to 0%. <br>
<br>
I will try with a selection of few rasters.<br>
<br>
<br>
</div>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt
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<div class="im">
><br>
> I guess this is a good reason to explain because it is
so slow when in the<br>
> catalog there and many hundred of rasters.<br>
><br>
> Unfortunately I don't find any option in gdalbuildvrt
to add the extension<br>
> of every raster in the catalog.<br>
<br>
</div>
There's none : the above information that is generated by
default is sufficient.<br>
<br>
</blockquote>
<div><br>
Sorry Roualt,<br>
the catalog give the start point and the number of pixel , but
miss the size in meters or "unit of map" of every pixel so for
me was not possible to detect the bbox of every raster.<br>
Perhaps in the overview there is the missing information ?<br>
<br>
>Best regards,<br>
><br>
>Even<br>
</div>
</div>
<br>
Thx,<br>
Andrea.<br>
<br clear="all">
<br>
-- <br>
-----------------<br>
Andrea Peri<br>
. . . . . . . . . <br>
qwerty àèìòù<br>
-----------------<br>
<br>
<br>
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</blockquote>
We have discussed this problem with Even. I'll fix it. The work is
in process.<br>
<br>
Best regards,<br>
Dmitry<br>
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