Table 1.

Annotation categories.

Categories	Subcategories
Technology	Pencil, Roller, Pen, Pressure scratch, chalk, Stencil, Spray can, Other
Carrier medium	Trailer, Vending machine, Railway line, Tree/Plant, Ground, Mailbox, Bridge, Bus, Container, Downpipe, Window/Blind, Railing/Handrail, Closed interior, Freight train, Hall of Fame, Stop noise barrier, Truck, Mast, Waste/Disposal container, Park bench, Passenger train, Car, Column/Pillar/Support, Display, Case Sign, Play/Sports equipment, Sticker, Road salt container, Electricity/Distribution box, Telephone box, Gate, Stairs, Door, Subway/S-Bahn Subway/S-Bahn/Passenger train - inside underpass, Wall Fence, Other, Undefined
Surface	Asphalt, Concrete, Glass, Wood, Ceramics, Plastic, Metal, Natural stone, Paper/Cardboard, Plaster, Exposed, Aggregate, Concrete Brick, Other, Undefined
Type	Character, Comment, Co-Construction, Composition, Piece/Writing/Style, Sketch, Saying/Concept call, Stencil, Tag(s), Throw Up, Otherwise
Subject area	Drugs, Erotic, Film, Peace, Football, Sports, Violence, Culture Art, Love, Music, Politics, Police, Racism, Religion, School, Death, Environment, Behavioural standard, Economy, Other, None