Your name is attached to your labels so we can measure agreement between labellers. Affiliation and email are optional and are only used to credit contributors and follow up on questions.
A previous viewer saw this differently
Take another look at the three images. If you are confident, keep your label and the earlier one will be flagged for review.
If you are not sure, click Unsure. A guessed label is worse than no label. Unsure counts as a real answer: two viewers marking a pool Unsure settles it just like any other agreement, and choosing Unsure never triggers the disagreement check.
Each item is one salt-marsh pool in one year of aerial imagery. The yellow line is the mapped pool polygon, the cyan line is the analysis window around it, and the red fill is the water class the automatic method chose. Judge whether the red matches the water you can see, using the plain band image and the true-colour image for reference.
1
Good: red covers the water and little else. Also good when the polygon is all land and nothing (or almost nothing) is detected: no water, none found, and the pool may form later in the series.
2
Over-detected: red spills well beyond the water (dark marsh, shadow, mud), or water is detected where there is only land.
3
Under-detected: clear water left out of the red class.
4
Bad Detection: the water class is wrong because of algae, shadow, sun glint or bright water, not because of the polygon. Floating algae counts as water (the area under it is inundated); it often shows as a bright green mass inside a pool, so if the red stops at an algae mat, choose Bad Detection.
5
Tidal-connected pool: the pool is open to a creek or channel in this image, so its water level follows the tide.
6
Bad polygon: the yellow outline is not a pool (channels, ditches, all trees, structures, open water).
7
Unsure: cloud, haze, resolution, or ambiguity.
←
Undo your last label (records an undo, nothing is deleted).
→
Skip this item for now.
↑↓
Zoom the images in and out.
Space
Toggle the red water class on and off in both images (O does the same; clicking an image does too).
R
Reload the images if one comes up blank.
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Once two different viewers give a pool the same label it counts as corroborated and is not shown again. If your label differs from an earlier viewer's you get a chance to look again; keeping your label flags the earlier one for review. Your overall total is kept under your name.
By default you see pools of 900 m² and larger in Maine, Massachusetts and New Hampshire. Use Advanced below the buttons to switch to smaller pools or other states.