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Question

FME and clipping ECWs

  • 14 December 2012
  • 3 replies
  • 18 views

Has anyone tried to clip an ECW using a shapefile? For some reason the clipper does not respond to the ecw format the same as it does for others. Having the ouput routed to the viewer shows a clipped image. However, when you open the output file again in either the view or in another program the file is back to its original shape.  If i do the same process in arcCatalog, (extract by mask) it works, but it is very slow and requires a few other processes to extract the data afterwards to make it usable.
Hi,

 

 

Clipping a reaster is something that FME does easly, however when saving a temp ffs feature, to use in the visualizer the run time can increase.

 

 

When clipping a raster it is advisable to make use of the bounding box option in the raster reader to minimize the data size.

 

 

You can do the following:

 

  • Generate a ecw to ecw workspace.
  • Open the shp in the viewer for the bounding box coordinates.
  • Feed the bounding box coordinates to the ecw reader and set the clip to extents to yes.
  • Add a clipper and your clipper feature to the ws.
  • Set up the clipper and run the ws.

 

Hope this helps,

 

Itay

 

 


This should work... What version of FME are you using? The Clipper behaviour is changing in FME 2013.

 

 

Keep in mind that if you clip area is irregular (i.e. not rectangular) the output will still be rectangular, filled out with black or nodata pixels.
You certainly need to be aware of the output format you are writing to. Some formats support transparency and some don't, some support nodata and some don't... so be careful how you inspect your processes results once you have written it out.

 

 

There's an example here of presumably what you'd like to achieve:

 

 

http://fmepedia.safe.com/articles/Samples_and_Demos/Raster-Clipping

 

 

Also, the Clipper 'has' changed lots over FME's history and will change again as RedGeographics mentions. Make sure that you are not copying an old Clipper out of an old workspace in a more recent FME. Add the Clipper directly from the Transformer Gallery, this is why:

 

 

http://fmepedia.safe.com/articles/How_To/Transformer-Versioning

 


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