From 6080cf1183109b5884c26e4475246c9259a4c1d5 Mon Sep 17 00:00:00 2001
From: Shreeraj Jadhav <shreerajjadhav@gmail.com>
Date: Fri, 11 Mar 2022 14:04:39 -0500
Subject: [PATCH] BUG: Copy direction cosines to exported image data

Copy direction cosines (DirectionMatrix) from vtkMRMLVolumeNode to the
extracted vtkImageData before exporting. This is in concurrence with other
grid related metadata such as origin and spacing, that need to be copied
before exporting vtkImageData.

Refer to discussion here [1] for the necessity to do this.
[1] https://github.com/Slicer/Slicer/blob/d010e8c075a9a66ce21a38ed549a20296ab7669d/Libs/MRML/Core/vtkMRMLVolumeNode.h#L174

Addresses issue https://gitlab.kitware.com/aeva/aeva/-/issues/273
---
 SMTKFileWriter/Logic/vtkSlicerSMTKFileWriterLogic.cxx | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/SMTKFileWriter/Logic/vtkSlicerSMTKFileWriterLogic.cxx b/SMTKFileWriter/Logic/vtkSlicerSMTKFileWriterLogic.cxx
index dfcdfc0..0720d1d 100644
--- a/SMTKFileWriter/Logic/vtkSlicerSMTKFileWriterLogic.cxx
+++ b/SMTKFileWriter/Logic/vtkSlicerSMTKFileWriterLogic.cxx
@@ -302,6 +302,9 @@ bool exportVolumeNodeToAevaSMTKResource(vtkMRMLVolumeNode* volumeNode,
   image->DeepCopy(nodeImage);
   image->SetSpacing(volumeNode->GetSpacing());
   image->SetOrigin(volumeNode->GetOrigin());
+  double dirs[3][3];
+  volumeNode->GetIJKToRASDirections(dirs);
+  image->SetDirectionMatrix(dirs[0][0], dirs[0][1], dirs[0][2], dirs[1][0], dirs[1][1], dirs[1][2], dirs[2][0], dirs[2][1], dirs[2][2]);
 
   auto modelName = std::string(volumeNode->GetName());
   return addVTKImageDataToAevaSMTKModelResource(image, resource, modelName, exportPath);
-- 
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