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<div class="moz-cite-prefix">The functions are to allow mapping
between logical and physical pixel values. This is very common in
e.g. elevation DEMs.<br>
<br>
Applying them is done by the calling code. At least, I haven't
seen any routines in GDAL that <br>
would apply them for you.<br>
<br>
Ray<br>
<br>
<br>
On 6/22/2015 7:50 AM, Alexander Bobkov wrote:<br>
</div>
<blockquote cite="mid:558820B9.80003@gmail.com" type="cite">
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Hi,<br>
<br>
What is the intended usage of methods
SetScale/GetScale/SetOffset/GetOffset of the GDALRasterBand class?<br>
<br>
Documentation says that<br>
<blockquote type="cite">
<p>This value (in combination with the <a
moz-do-not-send="true" class="el"
href="http://www.gdal.org/classGDALRasterBand.html#ab62e0761dde3e3b76f83155920275e4f"
title="Fetch the raster value offset.">GetOffset()</a>
value) is used to transform raw pixel values into the units
returned by GetUnits(). For example this might be used to
store elevations in GUInt16 bands with a precision of 0.1, and
starting from -100.</p>
<p>Units value = (raw value * scale) + offset</p>
</blockquote>
<br>
Who is responsible for applying the formula: client code
before/after RasterIO operation, or driver code inside
IReadBlock/IWriteBlock methods?<br>
<br>
<span>Best regards, </span><br>
<span>Alexander Bobkov</span><br>
<br>
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