Annotation types


Below you will find a table with all the annotation answer types that are currently supported on Grand Challenge.

Answer type Description Stored as Sidenote
Point single point 3D location of the point (json) -
Multiple points multiple points array of points (json) -
Distance measurement single line drawn on a single plane 3D locations of the start and end positions of the line (json) -
Multiple distance measurements multiple lines, each drawn on a single plane array of lines (json) -
2D Bounding Box rectangle drawn on a single plane 3D locations of the four corners of the rectangle (json) -
Multiple 2D Bounding Boxes multiple rectangles, each drawn on a single plane array of rectangles (json) -
Line line drawn on a single plane array of 3D locations of the seed points of the line (json) -
Multiple lines multiple lines, each drawn on a single plane array of lines (json) -
Angle two lines that do not need to intersect two sets of two 3D locations marking the start and end point of the two lines 1
Multiple angles multiple angles array of angles (json) 1
Polygon shape drawn on a single plane array of 3D locations of the seed points of the polygon (json) 2
Multiple polygons multiple shapes, each drawn on a single plane array of polygons (json) 2
Mask multiple shapes, each drawn on a single plane mha file -

Sidenotes:

1). For calculating the angle between two lines that intersect the angle is calculated on the closest point on the intersected line. This results in an apparent "jumping" of the calculated angle (see video), but this is merely the result of the change in the reference point. The location of the dashed line and the label shows which angle is calculated.

2). For (Multiple) polygons answer types, it is possible to create a large (number of) polygon(s) for a single question. This can lead to issues when saving these answers to Grand Challenge, as the answer becomes very large. You should consider using the Mask answer type if you expect a high number of polygons. With the option to switch between editors, you can utilize the polygon tool options and the mask tool options.


Use Mask answer type if you expect a high number of annotations for a single question or you if prefer your answer in image format
Use Polygon or Multiple polygons answer type if you don't expect a high number of annotations for a single question and you prefer the answers in a json format