Tips for labeling cuboid sequences
This page describes some tips and tricks to label cuboids in point cloud sequences faster.
By labeling object by object, we mean first labeling an object in the whole sequence, before moving on to the next object. This is typically easier and faster than labeling all objects on the first frame, then all objects on the second frame, and so on.
Your mouse is perfectly suitable for quickly drawing a cuboid or for moving it to roughly the right position. However, for fine adjustments, you’re probably better off using your keyboard. Segments.ai has hotkeys for almost everything, including for moving a cuboid and for changing its dimensions. Better still, you can customize all the hotkeys to your liking:
Keyframe interpolation is enabled by default on point cloud sequences with cuboid annotations. It allows you to label a sequence perfectly by only labeling a few “key” frames, while the rest of the frames are completed automatically. On Segments.ai, there are also remove-keyframes that indicate when an object disappears. More precisely, a remove-keyframe means that the object is not present in that frame and all frames before the next normal keyframe.
You can learn about adding, moving, and removing keyframes on this page:
An example of keyframes (blue diamonds) and a remove-keyframe (grey circle with cross).
In order to find objects to label, you can use the main point cloud viewer. You can move through the interface either by using your mouse or the hotkeys (
w, a, s, d by default). Learn more about navigating the 3D scene on the following page:If the point cloud sequence has images associated with it, they can often be helpful for locating objects that might otherwise be hard to spot in the point clouds. Learn more about using images in the 3D interface on the following page:
- 1.Go to the first frame where the static object is visible.
- 2.
- 3.
- 4.Disable the merged point cloud view.
- 5.Go through the sequence to find the frame where the object disappears.
- 6.
Add an
is_static track-level attribute to the categories that can be static (see Configure the label editor). When this attribute is checked, you can edit the position/dimensions/rotation of a cuboid in one frame, and these changes will be applied to all other frames automatically.
Use the merged point cloud view to see the full dimensions of a static object.
- 1.Go to the first frame where the static object is visible.
- 2.
- 3.Go through the sequence to find the last frame where the object is visible.
- 4.
- 5.
- 7.Adjust the object in the frames where the cuboid’s position is the farthest away from the real object’s position. Keyframe interpolation will interpolate the object linearly in the frames in between. If the object does not move linearly, use smart propagation to propagate the cuboid automatically.
- 8.When the sequence is roughly labeled, go through the sequence by using the arrow keys and make fine adjustments using keyboard hotkeys.
Use batch mode to quickly adjust a cuboid in a point cloud sequence.
Labeling a static object that starts moving is basically the same as labeling a dynamic object. To label the static part:
- 1.Place a keyframe on the first frame where the object is static.
- 2.
This way, you make sure that the object remains static between the keyframes.
Last modified 5d ago