Union in Model Builder does not merge polygons. It copies them as they are in the source layer

Question

Hello everyone,

I am looking for a way to merge all the polygons with a specific condition in another polygon layer.

I am creating a feature layer with a subset of  the polygon feature class and when I run the Union the final result does not merge the polygons I selected.

This is what I am doing

in Model Builder

- Select all polygons from FC grid polygon  that are located in Area =1

- run Union tool

This creates a new FC that  shows the same subset, not the expected result only 1 polygon.

What am I missing?

Thanks

Jose

DanPatterson · Answer

An edit session is a different environment than modelbuilder and their behaviour isn't the same

JoseSanchez · Answer

Thank you for your answer Mehdi and Dan,

I am confused because with ArcMap I am able to select the same out put layer, open an edit session, select all the polygons form my select, run the Union and it merges all the polygons in one.

So the Union in ArcMap does not work the same way as the Union in ModelBuilder.

DanPatterson · Answer

That has already been suggested....