Hello, Does anyone know this question? 

When I do the clip operation of two polygon layers, invalid geometry error rises.

 

 

And after my test, I knew it's the aggregator operation generates some self-intersection problems. 

 

 

In my test, I generate a Polygon Layer which contains some small polygons, and some are overlapped(here we name it as Layer A), then I use dissolve operation in ArcGIS to dissolve these polygons(here we name it as Layer , next I use the aggregator operation in FME to aggregator all polygons(here we name it as Layer C). 

 

 

Then I check geometry for Layer B and Layer C. Layer B is ok, having no genometry problems, whereas the Layer C has self-intersection problem. 

 

 

And when I look into Layer B and Layer C, I found that in Layer B, all the polygons is dissolved, including those overlapping parts. However, in Layer C, those overlapping parts are ignored. (The pictude is as follows:) 

 

 

So, is the aggregator operation in FME doesn't equal to the dissolve operation in ArcGIS? If so, are there any similar operations I can use in FME which considering these overlapping parts when dissolving? 

 

 

 

nOriginal polygons which have overlapping parts]

 

 

 

3Result of dissolve operation in ArcGIS]

 

 

 

wResult of Aggregator Operation in FME]