Intersection of two feature

Question

Hi forum

I need your help.
I would like to create a function that calculates the intersection area of two features.
I use ArcMap 9.3.1, ArcObjects 9.3 and .NET language (particularly C#).
I would create a Tool Command that interset two Feauture of two different Personal Geodatabase (MDB).
I have no idea how to do it and I did not find code examples on the forum.
Could you suggest some code or some link, please?

Thanks in advance!

WeifengHe · Answer

You can store the result geometry to database or draw in ArcMap to verify whether or not the output is correct.

There is code snippet in ArcObjects SDK to select map features by attribute query.
http://help.arcgis.com/en/sdk/10.0/arcobjects_net/componenthelp/index.html#//004900000088000000

You can also select the feature using IFeatureClass::Search with query filter set, this will return a feature cursor.  Call IFeatureCursor::NextFeature gets the feature object you want.

FilippaFideria · Answer

In order to get the area of intersection, both input geometries have to be polygon type geometry, and you need to choose the result dimenstion to be esriGeometry2Dimension.  And you will need IArea interface to get the area.

ITopologicalOperator t = polygon1
IGeometry g = t.Intersect(polygon2, esriGeometry2Dimension)
IArea a = g
a.Area is what you want.

There is no behavior change between 9.3 and 10 for Intersect method.

Thanks thanks thanks a lot for reply!!!
I'm not an expert with ArcObjects development and I think that the argument of intersectios is very difficult!
I have tested your code and something happens but I don't understand if the result is correct.

How can I pass to the code suggested by you, a selected feature?
I know how select a feature but I don't know how assign a selected feature to:
 ITopologicalOperator t = (ITopologicalOperator)Feat.Shape;
Instead of (ITopologicalOperator)Feat.Shape there should be (ITopologicalOperator)selectedFeature.

How can I do this?

Thank thanks thanks so much!

WeifengHe · Answer

In order to get the area of intersection, both input geometries have to be polygon type geometry, and you need to choose the result dimenstion to be esriGeometry2Dimension.  And you will need IArea interface to get the area.

ITopologicalOperator t = polygon1
IGeometry g = t.Intersect(polygon2, esriGeometry2Dimension)
IArea a = g
a.Area is what you want.

There is no behavior change between 9.3 and 10 for Intersect method.