J . A . Corbacho et al .: Radioprotection 2024 , 59 ( 2 ), 80 – 87 85 Fig . 3 . A ) Ortho-image of the study area showing drone measurements points . B ) Histogram of dose rate data recorded by drone . C ) Variogram . D ) Ambient Equivalent Dose Rate H *( 10 ) contours map . Red dots : H *( 10 ) measurements recorded by RS200 ionisation chamber . Blue number : H *( 10 ) values measured by RS200 . Green number : Identification point at Table 1 . E ) Cross correlation between dose rate data measured and estimated by kriging spherical interpolation . F ) Standard deviation map obtained from kriging spherical interpolation .