Dynamo Python Script to retrieve all visible elements on a view.

Dynamo_AllElementsVisibleByView.py

# To be pasted in a Dynamo Python Script node.
import clr
clr.AddReference('ProtoGeometry')
from Autodesk.DesignScript.Geometry import *

clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *

clr.AddReference("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager

doc = DocumentManager.Instance.CurrentDBDocument
view = UnwrapElement(IN[0])

OUT = FilteredElementCollector(doc, view.Id).ToElements()