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The WMS server of Iowa State is serving data for the GOES-13 satellite in the visible channel. As best as I can tell, the data is misaligned with other data sources. For example, in a WMS client, superimposing Blue Marble data, or any data containing political boundary lines, over on top of the Visible GOES-13 data from Iowa State, results in an apparent misalignment.

The Iowa State data (I think) is displaced about 6 pixels towards the east. You can see it here, towards the middle of the image, where the land comes to a point (North Cape, Prince Edward Island, Canada, 47.06N, -64.00W).

enter image description here

Iowa State re-projects the raw feed from NOAA into EPSG:4326 using something called GDAL. Here is their code:

https://github.com/akrherz/pyWWA/blob/master/gini2gis.py#L160

My questions.

  • Can you confirm using your own WMS client that the problem exists, and lies with the Iowa State WMS server?
  • From a cursory examination, do you see anything weird in the Iowa State code that does the re-projection?

I have been in contact with Iowa State about the issue, but unfortunately they aren't pursuing it.

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    $\begingroup$ Can you elaborate on why you think the data is misaligned? It might aso help to provide an equivalent image from a source you consider aligned. What does the IR image for this time and region look like? $\endgroup$ – casey Oct 20 '14 at 16:36
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    $\begingroup$ I think it's misaligned since I'm comparing it to N other data sets. The N data sets agree with each other, but not with the Iowa State data. I have no data regarding the IR channel on this point. I'm not using the IR data. In addition, the spatial resolution of the IR data is much lower, so, if the same mismatch existed in IR, it would be a lot harder to detect. $\endgroup$ – John O Oct 20 '14 at 18:17

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