Polyline Annotation Case Study
Label the Target
Underline the lines in the image and label their attributes.
1. Scenarios That Do Not Need Annotation
(1) No Objects That Need to be Annotated
In normal road scenarios, when the lane line is completely invisible due to damage, or there is no line in the image, it is not necessary for annotation or any operation.
(2) Image Quality
The image can be skipped due to poor quality.
2. Hard Scenario
(1) Old and New Lanes Overlap
When old and new lanes overlap, it is labeled with a [hard scenario] tag. No other operations need to be done.
(2) Twisted Lane Lines
When the lane line fails to connect due to road resurfacing or other reasons, it is labeled as a [hard scenario] tag. No other operations need to be done.
(3) Roads within Park or Other Areas
When the image scenario is located on an internal road such as a park, it is labeled with a [hard scenario] tag. No other operations need to be done.
(4) Temporary Road Changes
When a temporary path change occurs in an image scenario, it is labeled with a [hard scenario] tag. No other operations need to be done.
(5) Highway Toll Station
When the image scenario is a highway toll station, it is labeled with a [hard scenario] tag. No other operations need to be done and work on the next image.
(6) Including Parking Line
When a parking spot appears in the image scenario, it is labeled with a [hard scenario] tag, do not do other operations, and work on the next image.
(7) Including Diversion Lines that Can’t Meet
When Y or V lines that do not intersect in the image, it is labeled with a [hard scenario] tag, do not do other operations, and work on the next image.
General Rules for Drawing Lines
1. The line needs to be drawn in the center of the lane line, with left and right excursion of no more than 2px. Deformation caused by uneven road surfaces also needs to be labeled in the center of the line.
2. The curb is labeled near the middle edge, that is, the lower edge of the labeled curb.
3. The line needs to be close to where the current car is, far away to where it can be seen, and the line needs to pass through the occlusions. But the imagination or extension length cannot exceed the visible length.
4. When the visible part of the lane line is smaller than the diameter of the circular ruler, the lane line does not need to be labeled.
5. When the dashed part of the lane line is smaller than the diameter of the inner circle of the ruler, the dashed end of the line does not need to be labeled.
6. All lines in the field of view should be labeled.
1. If there is an impassable isolation belt (such as flower beds, fences, etc.), there is no need to label the opposite lane line.
2. If there is a passable separation belt (such as a double yellow solid line), the opposite lane line should be labeled.
3. If the line of the opposite lane can be seen in the intersection, the line of the opposite lane should be labeled regardless of the variety of the separation belt.
4 If there are impassable isolation belts such as flower beds on the main road and the side road in the same direction, the same lane lines outside the isolation belt should also be labeled.
Type of Lane to be Labeled
In addition to the following categories, other special lines do not need to be labeled.
1. The line is used to separate the traffic flow in the opposite direction, which is generally located in the middle of the road.
2. The line is used to separate the traffic flow in the same direction, which is generally located in the middle of the road.
3. Road edge line: the common lines include a single white solid line, a single yellow solid line, an uncrossable fence/flower bed/green belt/cone bucket, etc.
4. This type of lane(double yellow line) is used to separate the traffic flow in the opposite direction. It is forbidden to cross the boundary of the opposite carriageway. The common lines include double yellow lines, left solid and right dashed lines, left dotted and right solid lines, a single yellow solid line, impassable fence/flower bed/plant belt/cone, etc.
5. Do not cross the dividing line of the same lane: It is used to prohibit vehicles from crossing the dividing line of the lane to change lanes or overtaking. This labeled line is a solid white line, or an impassable fence/flower bed/plant belt/cone, etc.
6. Stop line: the parking position when the vehicle gives way and waits for starting, etc. The stop line is a solid white line.
7. Y-shaped line: Y-shaped line is the lane line divided into two parts in the lane gradient area and the ramp entrance. The shape is similar to the English letter “Y”, including positive Y-shaped and inverted Y-shaped.
8. V-shaped line: V-shaped line is the boundary of a V-shaped area composed of two lines at the entrance of the lane, including positive V-shaped and inverted V-shaped.
9. Wide line of a fork in the road: labeled as a Y-shaped line. Remember the principle that the separation and confluence point is at the center of the first/last line segment.
The End of Dotted Lines:
1. When there is a long dotted line, the end of each dotted line needs to be labeled, and the point should be attached to the line.
2. When the dashed part of the lane line is smaller than the diameter of the inner circle of the ruler, the dotted end of the dotted line does not need to be labeled.
Lane Line Attributes
- Abrasion/no abrasion:
Choose according to whether the lane line has invisible abrasion.
Abrasion: Due to various external reasons, the paint of the lane line is lost or diluted, and the changing area exceeds 20% of the current lane.
Choose white, yellow, or other according to the lane color.
(1) Lines: Lines are completely attached to the road surface
(2) Curb: A curb is a road tooth composed of cement steps/plant belts/cones/fences and other objects.
1. Label the same lane in different frames with the same track ID
2. When the same lane line is not visible in some frames, try to label the same lane line with the same track ID by judging the preceding and following frames.
Two Special Scenarios
1. Imagination extension length does not exceed the visible length, except that the occlusion is in the middle.
2. The ego vehicle’s own occlusion: not counted as occlusion. The lane line occluded by the ego vehicle itself should not be labeled with the occlusion attribute.
1. For Lines
(1) If the lines are clearly visible, label them consecutively.
(2) If it is not visible or blurred, disconnect the annotation.
2. For Curbs (green belt curb/common curb)
(1) If it is an intersection, disconnect the sign.
(2) If it’s a safe Island, label it consecutively.
(3) If the zebra crossing is not an intersection, label it continuously.
3. For Cone /Fence
Label according to the actual position.
4. When the Middle Road Coincides with the Obstacle
Label the line under the obstacle.
For example: if there is a double yellow line under the fence, label the yellow line.
5. For Zebra Crossing/No Stopping Line/Parking Line/Safety Circle Line
If the parking line is beside the traffic road, the outermost vertical parking space line still needs to be labeled normally, but the horizontal parking line and those of residential areas and shopping malls are all not labeled.
6. For Serious Occlusion
No need to label it. Where vehicles or other unrelated objects account for more than 80% of the image, it shall be deemed as seriously occluded and don’t need to be labeled.
7. For That Is too Close to the Lane Line
When the lane line coincides with the curb after extension, only one curb can be labeled. There is no obvious physical road edge and only one curb is labeled.
1. Image Standards
No missed line, no mislabeled line, and no extra line.
2. Line Standards
(1) The line should be labeled in the center, with pixel error within 2px.
(2) All attributes are selected correctly.
(3) Track IDs are correctly divided.
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