Activity: Measure object shape parameters
- Open image: xy_8bit_labels__four_objects.tif
- Perform shape measurements and discuss their meanings.
- Explore results visualisation * Color objects by their measurement values.
- Add a calibration to the image and check which shape measurements are affected.
- Draw a test image to understand the shape measurements even better.
Activity: Explore sampling limits
- Draw a square (=circle) of 2x2 pixels (paper, whiteboard, …) * Measure area, perimeter and circularity * Discuss the results
- Discuss the England’s coastline paradox
True or false? Discuss with your neighbour!
- Circularity is independent of image calibration.
- Area is independent of image calibration.
- Perimeter can strongly depend on spatial sampling.
- Volume can strongly depend on spatial sampling.
- Drawing test images to check how certain shape parameters behave is a good idea.
- Especially surface and perimeter measurements are affected by sampling and resolution, see for example: * https://en.wikipedia.org/wiki/Coastline_paradox).
- Results visualisation: * https://imagej.net/MorphoLibJ#Grayscale_morphological_filters: Label visualization in 3D viewer