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Question

Extracting ECW Coordinate System Information


Hi,

I would like to know how I can extract the Coordinate System information contained in the header of several ecw files, using as a writer a xlsx or txt file.

Thanks!

5 replies

redgeographics
Celebrity
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You can use the CoordinateSystemExtractor transformer for that. Downside is that I think it has to read the whole ECW through a reader first.


redgeographics wrote:

You can use the CoordinateSystemExtractor transformer for that. Downside is that I think it has to read the whole ECW through a reader first.

Yes, I had tried to read the ecw and use CoordinateSystemExtractor transformer, but there's no result... I don't know if I'am doing anything wrong...


jovitaatsafe
Safer
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juanrodriguezso wrote:

Yes, I had tried to read the ecw and use CoordinateSystemExtractor transformer, but there's no result... I don't know if I'am doing anything wrong...

@juanrodriguezso​,

Can you confirm there's nothing resulting in the attribute _coordsys?

 

My test ECW file doesn't seem to have a coordinate system so I didn't get a value from the CoordinateSystemExtractor. Can you confirm that your source ECW when opened in a text editor shows the coordinate system information? If so, you could use a TextFile reader to read in your ECW's first few lines to extract that information perhaps?


juanrodriguezso wrote:

Yes, I had tried to read the ecw and use CoordinateSystemExtractor transformer, but there's no result... I don't know if I'am doing anything wrong...

Hi,

Finally I've got the results. I don't know why in several cases, FME don't recognize the Coordinate System. For example:

  • ecws in NAD83 : the attribut result is "_FME_0".
  • ecws in ED50 or WGS84 (ZONE 28), the result is "0".

I guess that it is because those systems are not defined in the FMD db....


bwhite
Contributor
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  • Contributor
  • August 5, 2021
juanrodriguezso wrote:

Yes, I had tried to read the ecw and use CoordinateSystemExtractor transformer, but there's no result... I don't know if I'am doing anything wrong...

A late reply, but I've only just started learning FME and only just tackled this very problem.

In my case, the issue with the coordinate system was due to the sidecar files (ers, eww, tab, aux etc.). I found that I was able to extract the correct coordinate system by temporarily putting these files into a new directory and running the work bench on only the ecw files.


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