Load / Save Viewpoint for Orthographic Camera

[JunShern]

Hi, thanks for all the awesome work on this library.

I'm looking for a way to save and load the viewpoint of the orthographic camera in the visualizer using the Python bindings. I am aware of this #597 which resulted in this example, but unless I am using it wrongly I believe that it only works for non-orthographic cameras. That is, when the FOV is set to 5, saving and loading produces a different view.

The closest lead I've found so far is in the visualizer commands Ctrl+C and Ctrl+V for storing and loading the view, which works perfectly for orthographic and any view. This is exactly the behavior I want but I have not found a way to achieve this programmatically in Python, and my guess is that this relies on the C++ ConvertFromViewParameters which is not exposed yet in the Python API.

https://github.com/intel-isl/Open3D/blob/995b646375121e348ff814b138a924bfac0f047e/src/Visualization/Visualizer/ViewControl.cpp#L96

This would be a great help to my projects, please help or let me know if I am missing something.

@syncle

[Walter0807]

I have the same problem. It seems not implemented yet.

[JReesW]

Hello, I was wondering if there are any updates on this issue?

Specifically the part where I can replicate the functionalities of Ctrl+C and Ctrl+V programmatically.
I wish to load the JSON generated by Ctrl+C from a file, such that the window opens with those camera settings.

[claudius-kienle]

As far as I know, there is currently no such functionality. But following code implements the same functionality:

def convert_from_view_parameters(vc, json_path: str):
    with open(json_path, "r") as f:
        js = json.load()
   vc.change_field_of_view(js['trajectory'][0]['field_of_view'])
   vc.set_front(js['trajectory'][0]['front'])
   vc.set_lookat(js['trajectory'][0]['lookat'])
   vc.set_up(js['trajectory'][0]['up'])
   vc.set_zoom(js['trajectory'][0]['zoom'])

The function can be called in the following way:

vis = o3d.visualization.Visualizer()
convert_from_view_parameters(vc=vis.get_view_control(), json_path="our/saved/view/parameters.json")