The 3D Polyline tool draws a path through a point-cloud sequence — for example, the route a robot or vehicle should follow. Unlike a flat line, a 3D polyline can have a different shape on every frame, so the path can start from the vehicle and bend around obstacles as the scene changes.
When to Use
Use a 3D polyline when you need a line that:
- lives in 3D space (over the point cloud), and
- can change frame to frame (the path moves as the vehicle moves).
If you only need one fixed line that stays the same across the whole sequence, use the regular polyline tool instead.
Getting Started
- Open a point-cloud sequence and switch to the Polylines editor.
- Click Add 3D polyline.
- Click in the 3D view to drop points along your path. Each click adds a point; the points connect into a line.
- The line snaps to the ground and can start from the vehicle’s position (the guideline shown on the floor), so your path begins in the right place.
Hold Ctrl while placing or moving a point to turn snapping off and place it exactly where your cursor is.
Working Across Frames
Each frame can have its own version of the line:
- Move to the next frame and the editor offers to copy the line from the previous frame so you don’t start from scratch.
- Adjust the copied line to match the new frame — for example, route around something that moved.
- Editing one frame does not change the other frames (each frame is saved on its own).
Start at the Vehicle
Use the Start at ego button (the car icon) to make the line begin at the vehicle on the current frame:
- If the line runs past the vehicle, the part behind the vehicle is trimmed off so the line starts right at it.
- If the line is entirely ahead of the vehicle, a new starting point is added at the vehicle and connected to the line.
The line’s shape on other frames is not affected. The button does nothing if the line already starts at the vehicle, or if the vehicle’s ground position hasn’t been worked out for this frame yet.
Shared Points
If a point sits in the same spot on more than one frame, moving it moves it on all of those frames at once — handy for keeping the overall path consistent. Hold Ctrl while dragging to move it on the current frame only; from then on that point is independent.
Seeing Your Polylines
- 3D view: your 3D polylines appear over the point cloud.
- Camera images: the same polylines are drawn over the camera pictures, so you can check the path against what the camera saw.
- Colors: each separate polyline gets its own color, so different paths are easy to tell apart. The one you’re editing is highlighted.
The Side Panel
The list on the side shows every polyline in the sequence. From there you can:
- Show / hide a single polyline with the eye icon.
- Isolate one polyline to hide everything else and focus on it.
- Jump to a polyline — it moves the view to where that polyline is on the current frame.
Labels and Attributes
Select a polyline and open its attributes to classify it (for example, the type of path or lane). Your choices are saved with the polyline.
Saving
Your work saves per frame, just like other annotations. When you reload the sequence, every frame’s polyline comes back exactly as you left it. 
