* Implement nerfacto alpha transparency training
* Stop adding all ones alpha channel and clean up blend_background
* Make background_color a required argument in blend_background
* Enable alpha transparent training by default
* Improve background_color typing
* Blend uniform background color for metric computation
* Fix typing error
* Clean up typing
* Fix background_color to outputs assignment
* Model outputs returns unblended RGB (black bg) for random bg
* Update renderers
* Fix comments
* Add support for transparent BG for other methods
* Minor refac
* Fix get_background_color
* Fix typing error for blend_background
* Fix comments
* Export utils support transparency
* Pylint fix
* Fix pcd export masking
* Filter pcd view directions based on opacity
* Clean up get_rgba_image
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Co-authored-by: Jonas Kulhanek <jonas.kulhanek@live.com>
Nicholas PfaffandJonas Kulhanek
Matthew Tancik