Problem summary
When attempting to stitch a tile rendered exr image on Windows, the process fails with the following error message:
[ERROR python.root]: An AttributeError occurred in "MainBatch.py": 'module' object has no attribute 'spawnvp' Traceback (most recent call last): File "python/Main\Main.py", line 367, in File "python/Main\Main.py", line 313, in __main File "bin\python\Main\MainBatch.py", line 120, in Main File "bin\python\Main\MainBatch.py", line 676, in __stitchTiles File "bin\python\Main\MainBatch.py", line 739, in __stitchTilesForFrame AttributeError: 'module' object has no attribute 'spawnvp'
This is because os.spawnvp(), which is used in MainBatch.py, isn’t available on Windows (see
Python Documentation)
Steps to reproduce
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Open the Hello Pony example scene
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Connect a RenderOutputDefine node at the end, change locationType to file and specify a renderLocation
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Connect a Render node
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Save the file and close Katana
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Do a tile render of the file in Batch Mode, using the following commands and replacing ‘katana’ with the path to the Katana executable on your machine and the ‘--katana-file’ path with the path to the file you just saved:
katana --batch --katana-file=/tmp/test.katana --t=1 --render-node=Render --tile-render=0,0,2,2katana --batch --katana-file=/tmp/test.katana --t=1 --render-node=Render --tile-render=0,1,2,2katana --batch --katana-file=/tmp/test.katana --t=1 --render-node=Render --tile-render=1,0,2,2katana --batch --katana-file=/tmp/test.katana --t=1 --render-node=Render --tile-render=1,1,2,2katana --batch --katana-file=/tmp/test.katana --t=1 --render-node=Render --tile-render=0,0,2,2 --tile-stitch --tile-clean
Result: The tiles are rendered and they seem to be stitched together to a correct image, but before the stitch process can finish and the tiles can be cleaned up, the process fails with the error above.
Workaround
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Manually clean up the tiles by deleting them, as the stitched image still appears correct despite the error.
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Use a Linux OS for the tile stitching and cleanup process
Reproduced by support
Katana 2.5v1 - Windows 7
Katana 2.5v5 - Windows 7
Katana 2.6v1 - Windows 7
Katana 2.6v3 - Windows 7
Expected behaviour
Stitching and cleaning up the rendered tiles should work both on Windows and Linux
Actual behaviour
The process only completes successfully on Linux and errors on Windows.