PASCAL Visual Object Classes Challenge 2007 (VOC2007) Annotation Guidelines

http://host.robots.ox.ac.uk/pascal/VOC/voc2007/guidelines.html

This document reproduces the guidelines used for annotating images in the VOC2007 data set.

Guidelines on what and how to label

What to label
All objects of the defined categories, unless:
- you are unsure what the object is.
- the object is very small (at your discretion).
- less than 10-20% of the object is visible.
If this is not possible because too many objects, mark image as bad.

Viewpoint
Record the viewpoint of the ‘bulk’ of the object e.g. the body rather than the head. Allow viewpoints within 10-20 degrees.
If ambiguous, leave as ‘Unspecified’.

Bounding box
Mark the bounding box of the visible area of the object (not the estimated total extent of the object).
Bounding box should contain all visible pixels, except where the bounding box would have to be made excessively large to include a few additional pixels (< 5%) e.g. a car aerial.

Occlusion / truncation
堵塞 / 截断
If more than 15-20% of the object is occluded and lies outside the bounding box, mark as ‘Truncated’.
Do not mark as truncated if the occluded area lies within the bounding box.

Image quality / illumination
Images which are poor quality (e.g. excessive motion blur) should be marked bad. However, poor illumination (e.g. objects in silhouette) should not count as poor quality unless objects cannot be recognised.
Images made up of multiple images (e.g. collages).

Clothing / mud / snow etc.
If an object is ‘occluded’ by a close-fitting occluder e.g. clothing, mud, snow etc., then the occluder should be treated as part of the object.
mud [mʌd]：泥，诽谤的话，无价值的东西

Transparency
透明
Do label objects visible through glass, but treat reflections on the glass as occlusion.

Mirrors
镜子
Do label objects in mirrors.

Pictures
图片
Label objects in pictures / posters / signs only if they are photorealistic but not if cartoons, symbols etc.

Guidelines on categorisation

分类

Aeroplane
Includes gliders but not hang gliders
hang glider：悬挂式滑翔机，滑翔风筝

Bicycle
Includes tricycles, unicycles
tricycle [‘traɪsɪk(ə)l]：三轮车
unicycle [‘ju:nisaikl]：独轮脚踏车

Boat
Ships, rowing boats, pedaloes but not jet skis
jet ski：摩托艇
pedalo [‘pedələʊ]：脚踏船

Bottle
Plastic, glass or feeding bottles
feeding bottle：奶瓶，哺乳瓶

Bus
Includes minibus

Car
Includes cars, vans, people carriers etc.
Do not label where only the vehicle interior is shown.
vehicle interior：汽车内饰

Cat
Domestic cats (not lions etc.)
domestic cat：家猫

Chair
Includes armchairs, but not stools or benches

Dining table
Excludes coffee table or picnic bench

Dog
Domestic dogs (not wolves etc.)

Horse
Includes ponies, donkeys, mules etc.
donkey [‘dɒŋkɪ]：驴子，傻瓜，顽固的人

Motorbike
Includes mopeds, scooters, sidecars
scooters：踏板车，小轮摩托车，滑行艇

Potted plant
Indoor plants or outdoor plants clearly in a pot. Excludes flowers in vases

Sofa
Excludes sofas made up as sofabeds

Train
Includes train carriages, excludes trams
tram [træm]：电车轨道，煤车

TV/monitor
Standalone screens (not laptops), not advertising displays

Guidelines on segmentation

分割

What to segment
Objects whose bounding boxes have been labelled according to the above guidelines.
You may need to exclude backpacks, handbags etc. which were included in the bounding box.

Accuracy
Segment within 5 pixels. Labelled pixels MUST be the object;
pixels outside the 5-pixel border area MUST be background. Border pixels can be either. Use the tri-map displayed by the segmentation tool to ensure these constraints hold.
This may occasionally involve labelling pixels outside the bounding box.

Mixed pixels
Pixels which are mixed e.g. due to transparency, motion blur or the presence of a border should be considered to belong to the object whose colour contributes most to the mix.

Thin structures
Aim to capture thin structures where possible, within the accuracy constraints. Structures of around one pixel thickness can be ignored e.g. wires, rigging.
rigging：索具，绳索；装备，传动装置

Objects on tables etc.
If a number of small objects are occluding an object e.g. cutlery / silverware on a dining table, they can be considered part of that object.

Difficult images
Images which are overly difficult to segment to the required accuracy can be left unlabelled e.g. a nest of bicycles.

Wordbook

Visual Object Classes，VOC：视觉目标分类
Pattern Analysis, Statistical Modelling and Computational Learning，PASCAL

References