// Create a CurveElement filter to find CurveByPoints elements.
// It is necessary to use the CurveElementFilter, and not an ElementClassFilter or  the shortcut 
// method OfClass() because subclasses of CurveElement are not supported by those methods.
CurveElementFilter filter = new CurveElementFilter(CurveElementType.CurveByPoints);

// Apply the filter to the elements in the active document
FilteredElementCollector collector = new FilteredElementCollector(document);
ICollection<Element> founds = collector.WherePasses(filter).ToElements();


// Find all curve elements: use inverted filter with invalid CurveElementType to match elements
CurveElementFilter notCurveByPntFilter = new CurveElementFilter(CurveElementType.Invalid, true); // inverted filter
collector = new FilteredElementCollector(document);
ICollection<Element> notCurveByPntFounds = collector.WherePasses(notCurveByPntFilter).ToElements();

' Create a CurveElement filter to find CurveByPoints elements.
' It is necessary to use the CurveElementFilter, and not an ElementClassFilter or  the shortcut 
' method OfClass() because subclasses of CurveElement are not supported by those methods.
Dim filter As New CurveElementFilter(CurveElementType.CurveByPoints)

' Apply the filter to the elements in the active document
Dim collector As New FilteredElementCollector(document)
Dim founds As ICollection(Of Element) = collector.WherePasses(filter).ToElements()


' Find all curve elements: use inverted filter with invalid CurveElementType to match elements
Dim notCurveByPntFilter As New CurveElementFilter(CurveElementType.Invalid, True)
' inverted filter
collector = New FilteredElementCollector(document)
Dim notCurveByPntFounds As ICollection(Of Element) = collector.WherePasses(notCurveByPntFilter).ToElements()