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cite="mid:CAE=8kmmoJfoto0T488JBPEnk0Ws+FQ0KYGQRAPRBJd-8g_Duiw@mail.gmail.com">
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<div><br>
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<div>Is there any way to check for this or protect against it
from the client side, or do you just have to be experienced
with a given WMS service?</div>
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</blockquote>
Not much to do on the client side, except checking that if you got a
all-white image, it is probably not what you want, and retry at a
coarser resolution. I guess such a logic could potentially be
implemented in the WMS driver, but it could cause confusion to end
users (the driver would have to upsample the downsampled request,
and so the user might not realize that they didn't get data at the
resolution they requested)<br>
<blockquote type="cite"
cite="mid:CAE=8kmmoJfoto0T488JBPEnk0Ws+FQ0KYGQRAPRBJd-8g_Duiw@mail.gmail.com">
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<div><br>
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<div>Thanks again,</div>
<div>carl</div>
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<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sat, Aug 21, 2021 at 12:33
AM Even Rouault <<a
href="mailto:even.rouault@spatialys.com"
moz-do-not-send="true">even.rouault@spatialys.com</a>>
wrote:<br>
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<blockquote class="gmail_quote">
<div>
<p>Nothing wrong from your side, but the second command
probably selects a higher zoom level that has blank data
given the configuration/data available on the server side.<br>
</p>
<div>Le 21/08/2021 à 03:36, Carl Godkin a écrit :<br>
</div>
<blockquote type="cite">
<div dir="ltr">Hi,
<div>I'm very puzzled about why gdal_translate (v.
3.3.1) returns an all-white image when I select a
smaller area than with a working case with a larger
area.</div>
<div><br>
</div>
<div>These two command lines are exactly the same except
that the failing case has a smaller area:</div>
<div><br>
</div>
<div>gdal_translate "<a
href="https://basemap.nationalmap.gov:443/arcgis/services/USGSImageryTopo/MapServer/WmsServer?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=0&SRS=EPSG:4326&BBOX=-179.999989,-89.000000,179.999988,89.000000"
target="_blank" moz-do-not-send="true">https://basemap.nationalmap.gov:443/arcgis/services/USGSImageryTopo/MapServer/WmsServer?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=0&SRS=EPSG:4326&BBOX=-179.999989,-89.000000,179.999988,89.000000</a>"
wms.xml -of WMS<br>
</div>
<div><br>
</div>
<div>gdal_translate \<br>
-projwin 524136.39 5229915.17 527111.89 5226499.96
\<br>
-projwin_srs EPSG:32610 \<br>
-outsize 2500 0 \<br>
wms.xml fails.tif<br>
<br>
gdal_translate \<br>
-projwin 517947.80 5235658.96 528189.82 5224344.74
\<br>
-projwin_srs EPSG:32610 \<br>
-outsize 2500 0 \<br>
wms.xml works.tif<br>
</div>
<div><br>
</div>
<div>Can anyone explain what's going on here and (most
likely!) what I'm doing wrong?</div>
<div><br>
</div>
<div>Thank you very much,</div>
<div><br>
</div>
<div>carl</div>
</div>
<br>
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My software is free, but my time generally not.</pre>
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