Coralscapes Dataset

The Coralscapes dataset is the first general-purpose dense semantic segmentation dataset for coral reefs. Similar in scope and with the same structure as the widely used Cityscapes dataset for urban scene understanding, Coralscapes allows for the benchmarking of semantic segmentation models in a new challenging domain.

Dataset Structure

The Coralscapes dataset spans 2075 images at 1024×2048px resolution gathered from 35 dive sites in 5 countries in the Red Sea, labeled in a consistent and speculation-free manner containing 174k polygons over 39 benthic classes.

Data Splits

The dataset provides three splits

• train - 1517 images across 27 dive sites
• validation - 166 images across 3 dive sites
• test - 392 images across 5 dive sites

Id	Name	Color	Description
1	seagrass		Seagrass
2	trash		Includes all kinds of marine litter. Most common are plastic items including bags, cups, and bottles, aluminum cans and glass bottles, as well as abandoned fishing material, and parts of boats and machines.
3	other coral dead		All other dead coral skeletons.
4	other coral bleached		All other bleached coral, including bleached soft coral.
5	sand		Loose, fine sand.
6	other coral alive		All other live corals. Includes corals in thin plate or encrusting growth form, soft corals, and corals that can not be clearly classified into the other classes.
7	human		The human class includes divers and snorkelers, of which sometimes only a hand or a fin is in the frame. Some ambiguity can arise when a human carries a transect tool that is not laid out on the ground, like a transect reel. In these cases, we generally decide this tool becomes part of the human polygon.
8	transect tools		This includes transect reels & spools, tags and markers placed on the reef, diving weights, surface marker buoys and the string attaching them to the ground or weights on the ground.
9	fish		Fish of all kinds.
10	algae covered substrate		Substrate covered in turf algae or other macroalgae, including fleshy algae and Turbinaria.
11	other animal		Includes starfish (except the crown-of-thorns starfish), feather worms, sea turtles, and other non-identifiable invertebrates or animals of which there are not enough annotations to warrant a separate class.
12	unknown hard substrate		Hard substrate that is part of the reef, which can not be identified into any of the other classes. Includes rocks and heavily decomposed coral skeletons. Also includes human-made structures (underwater infrastructure) such as pipes, pier columns, coral nursery tables, buoys and their lines, as well as boat anchors.
13	background		This class is assigned to pixels that are too far away or too blurry to be classifiable into any other class. This includes the water surface, which is sometimes visible.
14	dark		Parts of the image that are too dark to discern the benthic class.
15	transect line		Rolled out transect tape. Excludes reels or other strands of rope that are laid out.
16	massive/meandering bleached		Bleached massive corals or meandering corals that have decomposed enough so that the meandering structure is no longer visible.
17	massive/meandering alive		Corals in a massive growth form. Prominently includes Porites, Favia, Favites, and many others. Includes some likely meandering corals (like Platygyra) where the meandering structure can not be clearly identified.
18	rubble		Small loose fragments of rocky substrate or dead coral.
19	branching bleached		Bleached branching coral of all kinds, including bleached table acropora.
20	branching dead		Other dead branching coral, including acropora, pocillopora, and stylophora. When overgrown by algae, labeled as ‘algae covered substrate’.
21	millepora		The ‘fire coral’ Millepora is technically not a coral, but a hydrozoan. Appears most commonly in a branching form (Millepora Dichotoma).
22	branching alive		Branching corals that can surely be determined to be alive, but do not fit in to ‘table acropora alive‘, ‘acropora‘, ‘stylophora’, or ‘pocillopora’ because they are from a different genus or appear slightly blurred in the context.
23	massive/meandering dead		Dead massive corals or meandering corals that have decomposed enough so that the meandering structure is no longer visible.
24	clam		Live giant clams.
25	acropora alive		Acropora that do not grow in tabular growth form.
26	sea cucumber		Sea Cucumber
27	turbinaria		Colloqually the ‘scroll’ coral. Does not include the macroalgae genus Turbinaria.
28	table acropora alive		Acropora that grow in a tabular growth form.
29	sponge		Sponges of all kind.
30	anemone		Anemone
31	pocillopora alive		Clearly identifiable Pocillopora.
32	table acropora dead		Dead Acropora tables which are dead or collapsed but are not yet overgrown by algae. Parts visibly overgrown by algae are labeled as ‘algae covered substrate’.
33	meandering bleached		Bleached meandering corals (Lobophyllia, Symphyllia, Platygyra, etc.).
34	stylophora alive		Clearly identifiable Stylophora.
35	sea urchin		Sea Urchin
36	meandering alive		Corals of a meandering growth form. Includes Platygyra, Lobophyllia, Symphyllia.
37	meandering dead		Dead meandering corals (Lobophyllia, Symphyllia, Platygyra, etc.).
38	crown of thorn		Acanthaster planci, known to cause outbreaks in which it can severely reduce coral cover.
39	dead clam		Dead giant clams.

Number of annotated segmentation masks per class in the Coralscapes dataset splits for each of the 39 classes (shown with linear proportions on logarithmic scale).

License

Citation