Can you also show what your two input datasets look like?

So basically I use the buildingcs for the linkage. At the end, the list exploder shows the correct numbers of overlapped polygon (in attribute). However, they all show the same geometry polygon.

No idea why all show the same geometry

Hi @zacharylee1204​ , the SpatialRelator outputs the input Requestor features containing attributes/lists collected from spatially related Supplier features, so the ListExploder gives an identical geometry to every output features exploded from the same list.

If you need to transfer geometries of the related Supplier features to the resulting features, consider using the pair of GeometryExtractor and GeometryReplacer.

(1) Save the geometry of Supplier as its attribute with the GeometryExtractor, before the SpatialRelator.

(2) In the SpatialRelator, accumulate the geometry attributes from related Suppliers into the list.

(3) Restore the geometry with the GeometryReplacer, after the ListExploder.

In this case, "FME Binary" is the best geometry encoding type for the GeometryExtractor/Replacer.

Hope this helps.

If you are wanting your output to contain the supplier geometry rather than the requestor, i would use a GeometryExtractor prior to the SpatialRelator on your suppliers, include that in the list and then you can use a GeometryReplacer to rebuild the supplier geometries.

Thank you all, it works! :)