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Erasing (subtracting) and merging polygon layers,

 

 

I extracted two layers from the CAD file: Boundary layer and Landuse layer.

 

 

 

 

 

 

 

 

 

 

 

Now I want to derive the Roads layer by subtracting the Landuse layer from the Boundary layer. (in ArcGIS, the erase tool is used)

 

 

 

 

And then I need to combine the Landuse layer and Roads layer in one layer (in ArcGIS, the merge tool is used)

 

 

 

 

What might be the equivalent tools for Erase and Merge in the FME?

 

 

 

 

Thank you

 

 

Best

 

 

Jamal
Have you tried the clipper and writting all features into one output? or the UnconditionalFeatureMerger from the FME store?
Hi,

 

 

you can use a Clipper, like Itay suggests. Send the boundary to the CLIPPEE port and the landuse to the CLIPPER port. The features exiting the INSIDE port will be your roads layer.

 

 

To combine them with the land use polygons, just send both the land use and the roads features to the same output feature type.

 

 

David
Thank you very much Itay and David for the help.

 

 

The roads are obtained improperly from the Clipper tool!

 

 

 

The landuse layer is extracted from the CAD file properly

 

 

 

 

The boundary is extracted from the CAD file properly too.

 

 

 

 

The Roads are not derived properly from the tool. Please have a look on the mismatched polygon

 

 

 

 

What might be the issue here?

 

 

 

The CAD file is stored in the link below:

 

http://www.mediafire.com/download/3190am3f3tur4yj/Marda_Salfit_UrbanMasterPlan_02.dwg
Hi Jamal,

 

 

In my test using your data, there seems to be a special case where the Clipper doesn't work correctly if input polygons contain arc segments. This may be a Safe support matter.

 

As a present workaround, how about using the ArcStroker to change arcs to lines before clipping?

 

 

Takashi

There are more arcs in there being procesed correctly.

 

 

It seems that particular objects is somehow flawed/affected.

 

I tried rebuilding it in Autocad. It consists almost exclusively of arcs, but so do some other parts.

 

Autocad coould not connect. So i reset the endpoints to try to fix it.

 

Still no dice.

 

 

I have found the problem tho...:)

 

That particular object is 2 hatches on top of eachother.

 

Remove 1 in your dwg.

 

I did and it works as supposed.

 

 

 

Gio
fme will try to clip both the hatches, wich are the same..thats why.
Many thanks Takashi and Gio for the help.

 

 

 

Perfect Gio. The duplication of hatches is the issue. It works fine now as one of the hatches is deleted from the CAD file.

 

 

 

 

 

In our work environment, we heavily use hatches to describe the landuse. I’m wondering if the FME can detects the overlapped hatches and to delete the duplication.
Try the Matcher.
Yes as Itay says u can detect and remove duplicate geometry.

 

 

But ...so can Autocad.

 

 

Gio
Very much appreciated

 

 

best

 

 

Jamal

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