So I want to create following Worksspace:
processing --> feature (perimeter) -> RasterReader (clipped to perimeter) -> further processing
Question
dynamically read raster only in given extent
I would like to dynamically read a raster using FeatureReader or RasterReader (or anything else?) transformer. This works fine but I don't want to fully load the whole raster and I have not found an option how to tell these transformers only to read the raster in a given extent, as it is possible with the "normal" ArcSDE Raster Reader.
Hi,
did you try the FeatureReader with the extent bounding box as the Initiator feature? Set "Spatial interaction" to INTERSECTS.
David
Hi David,
Thank you for your answer. I have tried it and since the box and the raster intersect (so the condition is true I guess) the whole raster is loaded and not only the intersecting part...
Hi,
I believe the FeatureReader will read any (complete) feature that intersects with your Initiator. That means that if the Initiator intersects a tiny part of one big raster, that whole raster will probably be read. I do not think there is any clipping going on.
Could that be the case here?
David
Yes this is the case: I have one huge raster in an ArcSDE database and want to load only a small part of it for further processing. Since it is "one" raster, all of it is loaded.
In that case you could consider having a separate workspace to read the raster using the regular SDE Raster reader, with the extent parameters as published parameters. You can then call it from your current workspace using a WorkspaceRunner.
David
I wanted to avoid it since I already have a bunch of secod level workspaces and do not really wand to go into a third hierarchy. But if this is the only solution I guess I will do it. I thought since the normal reader provides the option to clip to a certain search envelope the reader-transformer can do it as well. Thanks for your help anyway!
Simon
+18- Safer
Hi,
You can adapt the FeatureReader where clause to provide you with the area of interest, have a look at the SQL generated by the reader (set up with the clip)and emulate the where part in the FeatureReader.
Hi Itay, thank you for your input. Unfortunately I am not able to find the SQL statement generated by the SDE Reader when reading the raster the "normal" way using a search envelope. I could not find anything in the window-log nor in the logfile provided by my workbench. Can you give me a hint where to search?
Thank you
Simon
+18- Safer
Hi Simon,
Normally this will appear in the logfile, however I am not 100% sure that this will be the case when reading a raster (works just fine for vectors), so by your answer I guess that is not the case. I would go with David's suggestion or clip the raster beforehand and read it with the RasterReader.
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