RandomSpot is a web based stereology tool which systematically places sampling points in a regular grid structure, within a region of interest (ROI) on a virtual slide.
Regions of interest should be made in Leica/Aperio ImageScope software and exported as an XML annotations file. Annotations can be square, circular or polygonal in shape. Once exported, the annotations file(s) can be uploaded to the system.
Users can set the number of points that they wish to add to their region of interest, with a tolerance limit, specified as a percentage.
More detailed instructions can be found once logged into the system.
The idea with hexagons is to reduce sampling bias from edge effects of the grid shape, which is related to high perimeter:area ratios. A circle is the lowest ratio, but cannot form a continuous grid, and hexagons are the closest shape to a circle that can still form a grid.
Also, if you are working over a larger area, a square grid will suffer more from distortion due to curvature than shapes like hexagons.
This paper (Birch, 2007) also presents a thorough comparison of rectangular and hexagonal grids for ecological applications, showing how hexagonal grids are preferable when issues of connectivity, nearest neighbourhood or movement paths are crucial aspects to be considered in the analysis
RandomSpot currently uses the Leica/Aperio XML annotation format in order to generate sampling points, and as such can only be viewed in the Leica/Aperio ImageScope software.
If you would like to use RandomSpot for other virtual slide viewing software, please submit a feature request detailing which system you require RandomSpot to support.
RandomSpot is designed using HTML5 and may not be fully compatible with older browsers.
If you believe that RandomSpot would be a useful tool for your research, get in touch with us via email so we can set you up on the system.