Saâd,<br><br>A VRT raster band can be derived from more than one source.<br><br>Offset and Scale elements apply to the whole VRT raster band.<br>The ScaleOffset and ScaleRatio perform the same task but it is done only on that particular ComplexSource.<br>
<br><div class="gmail_quote">On Fri, Mar 23, 2012 at 3:43 PM, Saâd HESSANE <span dir="ltr"><<a href="mailto:saad.hessane@gmail.com">saad.hessane@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hy all,<br><br>The vrt format allow defining the scale and offset element. But the documentation is not clear about that :<br><ul><li><b>Offset</b>: This optional element contains the offset that should be
applied when computing "real" pixel values from scaled pixel values on a
raster band. The default is 0.0.</li><li><b>Scale</b>: This optional element contains the scale that should be
applied when computing "real" pixel values from scaled pixel values on a
raster band. The default is 1.0.</li></ul><p>What that it's mean ? If the value of offset is 1 what that it's change?</p><p>And this two elements are use in the <b>VRTRasterBand</b> element. What about <b>ScaleOffset</b> and <b>ScaleRatio</b> in the <b>ComplexSource</b> element?</p>
<p>Thank you.<br></p>
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