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Hi,<br>
<br>
GDALDataset::RasterIO pass the request off to each band objects
rasterio methods with appropriate arguments<br>
In GDALRasterBand::RasterIO
(<a class="moz-txt-link-freetext" href="http://www.gdal.org/classGDALRasterBand.html#a5497e8d29e743ee9177202cb3f61c3c7">http://www.gdal.org/classGDALRasterBand.html#a5497e8d29e743ee9177202cb3f61c3c7</a>)<br>
<br>
<span style="color: rgb(0, 0, 0); font-family: 'Lucida Grande',
Verdana, Geneva, Arial, sans-serif; font-size: 12px; font-style:
normal; font-variant: normal; font-weight: normal; letter-spacing:
normal; line-height: normal; orphans: 2; text-align: start;
text-indent: 0px; text-transform: none; white-space: normal;
widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto;
-webkit-text-stroke-width: 0px; background-color: rgb(251, 252,
253); display: inline !important; float: none;">"Some formats may
efficiently implement decimation into a buffer by reading from
lower resolution overview images.</span>"<br>
<br>
So you don't need to choose the right overview level by yourself.
Usually it selected automatically. You can inspect GDAL sources for
how it chosen. GDAL don't have the special function to find out
which overview level is chosen.<br>
<br>
Best regards,<br>
Dmitry<br>
<br>
<div class="moz-cite-prefix">14.12.2012 11:24, HariPrasad пишет:<br>
</div>
<blockquote cite="mid:1355469854703-5022926.post@n6.nabble.com"
type="cite">
<pre wrap="">Thanks Dmitry for your replay.
I did that using IRasterIO(), but non of the IRasterIO() parameters has
which overview its displaying. (i.e overview number). How can i know which
overview it has displayed?
I used GetOverview(int). I was able to get the overview numbers. But when i
zoomed to maximum the base image has to be displayed instead of overview if
i am not wrong, which i am not getting the base image number.
am iam thinking in right direction?
--
View this message in context: <a class="moz-txt-link-freetext" href="http://osgeo-org.1560.n6.nabble.com/Overviews-using-GDAL-tp5022226p5022926.html">http://osgeo-org.1560.n6.nabble.com/Overviews-using-GDAL-tp5022226p5022926.html</a>
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</pre>
</blockquote>
<br>
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