Average root density | Ratio between foreground and background pixels of the extracted root | Scoring of density |

STA *X* | Angle between an RTP at *x*% length and the *x* axis calculated as ar*ctan(m),* where *m* is the slope of the fit line | Shovelomics angle at certain depth for dicots |

Dominant STA 1 and 2 | Average of the first and second significant peak in the in the histogram of calculated solid tissue angles binned in 10° steps | Shovelomics angle for dicots |

Min/median/max STA | Minimal, median, and maximal of all calculated STAs | N/A |

Dominant RTA 1 and 2 | Average of the first and second significant peak in the histogram of calculated RTAs binned in 10° steps | N/A |

Min/median/max RTA | Minimal, median, and maximal of all calculated RTAs | N/A |

Median/max width | Median/maximum of the calculated width in the width height diagram | Only max width or selected representative width |

D10 to D90 | Accumulated width over the depth at *x*%. The change in width accumulation denotes a change of the root-top angle | N/A, but closely related to the root-top angle for maize |

DS10 to DS90 | Slope of the graph of D values | N/A |

Spatial root distribution (as separate *X* and *Y* components) | Displacement of the center of mass between the bounding box of the RTP skeleton and the RTP skeleton excluding the central path | N/A |

Stem diameter | Diameter at the beginning of the root top. We use the first branching point of the filtered medial axis as a characteristic diameter | Caliper measurement |

Central path diameter *X* | The diameter at *x*% length of the central path | Diameter at a defined depth below the soil line |

Max diameter at 90% depth | Maximal tip diameter in the last 10% of the image | Measured for dicots |

Tip diameter distribution | Exponent of the exponential function fitted through the tip diameter histogram | N/A |

Median/mean tip diameter | Median and mean tip diameters of all tips | N/A |