Rotating a Plan View

Here is a query from the Autodesk Revit API discussion forum dealing with the rotation of a plan view ↗:

Question: I am trying to create rotated duplicates of existing views using the Revit 2013 API.

I managed to create the view, both as dependent and not. After this I activate the view crop box and make it visible.

I then create a rotation transformation. When I debug it, I can see that the transformation and rotation of the bounding box is ok.

I try to set the rotated bounding box as the crop box. However, this does not work, and all I get is the standard identity matrix.

I have a right handed rotation, and use basis Z as the rotation axis. I have a reference to a transaction inside the method, but have also tried to encapsulate the specific part into a sub transaction.

This way of doing things is according to the Revit 2013 API documentation. It states that the bounding box can be rotated, then used as section box/crop box, and provides to following example code for this:

private void RotateBoundingBox( View3D view3d )
{
  BoundingBoxXYZ box = view3d.SectionBox;
 
  if( !box.Enabled )
  {
    TaskDialog.Show( "Revit",
      "The View3D section box is not enabled." );
    return;
  }
 
  // Create a rotation transform
 
  Transform rotate = Transform.get_Rotation(
    XYZ.Zero, XYZ.BasisZ, 2 );
 
  // Transform the SectionBox 
  // with the rotation transfrom
 
  box.Transform = box.Transform.Multiply( rotate );
  view3d.SectionBox = box;
}

I tried to use it like this:

  ViewPlan rotatedView = doc.GetElement(
    viewToDuplicate.Duplicate(
      ViewDuplicateOption.AsDependent ) )
        as ViewPlan;
 
  rotatedView.CropBoxActive = true;
  rotatedView.CropBoxVisible = true;
 
  BoundingBoxXYZ box = rotatedView.CropBox;
 
  XYZ originOfRotation = 0.5 * (box.Max - box.Min);
  XYZ axizOfRotation = XYZ.BasisZ;
 
  Transform rotate = Transform.get_Rotation(
    originOfRotation, axizOfRotation, Math.PI );
 
  box.Transform = box.Transform.Multiply( rotate );
 
  rotatedView.CropBox = box;

I also tried using the ElementTransformUtils.RotateElement method.

Both approaches yield no result.

Manually I make sure the plan is situated to ‘Project north’, show the crop box, select it, rotate it and the view is rotated accordingly.

The desired result is a dependent view rotated at the point of creation. I need to create several views at once, e.g. 4-8 differently rotated ones of the same plan, to create evacuation plans.

Let me reiterate my requirement and manual solution:

Issue – Rotating view plans

For creating evacuation plans for a floor, I need to create rotated dependent views so that the person looking at the plan on the inside of a door sees the situation the same way as the corridor outside.

I can achieve it manually like this:

• Create the floor, i.e. when modelling the building.
• Apply all the required fire symbols.
• Create three duplicates as dependent views.
• Apply the crop region to each.
• Rotate each plan individually by rotating the crop box.
• Create filled regions to show which room the current plan applies to.
• Hide the ‘you are here’ symbols in all other rooms.
• Optionally rotate the symbols as well.
• Place these views on corresponding sheets.

This is obviously a very time consuming operation.

I have already implemented methods to create the fire and evacuation plans.

The issue I am now dealing with is the rotation of the crop region.

I do get the transformation, but I am not able to apply it to the crop region. Something fails and the transformation remains unchanged.

How can I fix this, please?

Answer: Yes, rotating a view ↗ in the user interface is perfectly straightforward, just as you say:

In the API, the issue is also clear: The element to rotate is not the view, but rather the crop box element associated to it.

If it is visible, it can be found using a filtered element collector taking document and view element id arguments.

Here is a macro that works based on your sample code:

  public void CreateDuplicatedRotatedCroppedView(
    Document doc )
  {
    View activeView = doc.ActiveView;
    View duplicated = null;
 
    using( Transaction t = new Transaction( doc ) )
    {
      t.Start( "Duplicate View" );
 
      duplicated = doc.GetElement(
        activeView.Duplicate(
          ViewDuplicateOption.WithDetailing ) )
            as View;
 
      t.Commit();
    }
 
    Element cropBoxElement = null;
 
    using( TransactionGroup tGroup
      = new TransactionGroup( doc ) )
    {
      tGroup.Start( "Temp to find crop box element" );
 
      using( Transaction t2 = new Transaction(
        doc, "Temp to find crop box element" ) )
      {
        // Deactivate crop box
 
        t2.Start();
        duplicated.CropBoxVisible = false;
        t2.Commit();
 
        // Get all visible elements;
        // this excludes hidden crop box
 
        FilteredElementCollector collector
          = new FilteredElementCollector(
            doc, duplicated.Id );
 
        ICollection<ElementId> shownElems
          = collector.ToElementIds();
 
        // Activate crop box
 
        t2.Start();
        duplicated.CropBoxVisible = true;
        t2.Commit();
 
        // Get all visible elements excluding
        // everything except the crop box
 
        collector = new FilteredElementCollector(
          doc, duplicated.Id );
        collector.Excluding( shownElems );
        cropBoxElement = collector.FirstElement();
      }
      tGroup.RollBack();
    }
 
    using( Transaction t3 = new Transaction( doc ) )
    {
      BoundingBoxXYZ bbox = duplicated.CropBox;
 
      XYZ center = 0.5 * ( bbox.Max + bbox.Min );
 
      Line axis = Line.CreateBound(
        center, center + XYZ.BasisZ );
 
      t3.Start( "Rotate crop box element" );
 
      ElementTransformUtils.RotateElement( doc,
        cropBoxElement.Id, axis, Math.PI / 6.0 );
 
      t3.Commit();
    }
  }

There are several noteworthy points in here.

All the transactions could be assimilated into one group, if desired.

The crop box element is retrieved using a clever trick: first hide it, retrieve the set V of all visible elements, unhide it and again retrieve all visible elements, this time excluding the set V. Clever, huh?