Root path space views

[emilk]

As requested by @nikolausWest, we want to be able to omit the leading world/ in our example paths.

For instance, a user can log to the paths

image
detections
text_logging

And then the viewer will automatically create two spaceviews:

• One called "2D" containing image and detections
• One called "text_logging"

Upside

Users can care less about what they log. Log to image and detections, and you can still overlay the detections on the image.

Downside

We encourage a less structured way to organize your entities.

TODO

A few steps to reach that in a nice way:

• Allow making the root (/) a space view
• Name space views based on last component name plus category (world/camera/video -> video 2D)
• Split ViewCategory into ViewCategory2D and ViewCategory3D
• Make sure we do the correct things with all the transform stuff everywhere

[jleibs]

"Make sure we do the correct things with all the transform stuff everywhere" carries some big assumptions.

This seems to necessitate default-connecting root-level paths with the identity transform (just like we do with other spaces), so that their siblings are are reachable.

I'm generally in favor of this because I think it's more globally consistent, but I want to make sure we're being explicit about the behavior and also defining the opt-out pathway? If you want truly isolated spaces does this mean explicitly logging, e.g. rr.unknown_transform("isolated") (maybe aliasing this as rr.disconnect_space("space") would be more clear, but same idea).

[Wumpf]

for the moment the trick would just be to not create a space view at root by default. That way they become opt in (at least for now). I don't think logging "permanent unknown transforms" is something we really need therefore.

[nikolausWest]

Fyi @Wumpf, we still can't log transforms to one below root:

rr.log_rigid3(
    "cam",
    child_from_parent=camera_from_world,
    xyz="RDF",  # X=Right, Y=Down, Z=Forward
 )

Gives this error:

Traceback (most recent call last):
  File "./examples/colmap/main.py", line 212, in <module>
    main()
  File "./examples/colmap/main.py", line 197, in main
    read_and_log_sparse_reconstruction(dataset_path, filter_output=not args.unfiltered)
  File "./examples/colmap/main.py", line 128, in read_and_log_sparse_reconstruction
    rr.log_rigid3(
  File "/Users/niko/src/rerun/rerun/venv/lib/python3.8/site-packages/rerun_sdk/rerun/log/transform.py", line 153, in log_rigid3
    bindings.log_rigid3(
TypeError: Transforms are between a child entity and its parent, so root entities cannot have transforms

[nikolausWest]

I'll still record videos as if we can but that means we need to fix this by launch

[Wumpf]

addressed in #1097

[Wumpf]

fix was premature and caused new issues. Taking another look at this on Monday