PROBLEM TO BE SOLVED: To accurately determine the discrimination of diseased trees (infected trees) from sound trees (uninfected trees) in a whole farm without requiring any special experience or skill.SOLUTION: A contraction determination method includes: an image acquisition step of acquiring a first satellite image as a monochrome satellite image obtained by imaging the whole region or partial region of a farm of para rubber trees and a second satellite image as a satellite image whose imaging range is the same as that of the first satellite image and which has sensitivity in at least a near-infrared region a branch end specification step of specifying the position of a branch end of a para rubber tree from the first satellite image acquired in the image acquisition step and a determination step of comparing the reflection intensity of the near-infrared region at the position of the second satellite image corresponding to the position of the branch end in the first satellite image specified by the branch end specification step with a predetermined threshold, and determining that the para rubber tree at the branch end is not diseased when the reflection intensity is less than the predetermined threshold, and determining that the para rubber tree at the branch end is diseased when the reflection intensity is equal to or more than the predetermined threshold.COPYRIGHT: (C)2014,JPO&INPIT【課題】特別な経験や熟練を必要とすることなく、農園全体の罹病木(感染木)と健全木(非感染木)との区別を精度よく判定可能とする。【解決手段】罹病判定方法は、パラゴムノキの農園の全域、または一部領域を撮像したモノクロの衛星画像である第1の衛星画像と、第1の衛星画像と撮像範囲が同一の衛星画像であって少なくとも近赤外領域に感度を有する第2の衛星画像とを取得する画像取得工程と、画像取得工程で取得された第1の衛星画像からパラゴムノキの梢端の位置を特定する梢端特定工程と、梢端特定工程で特定された第1の衛星画像内の梢端の位置に対応する第2の衛星画像の位置における近赤外領域の反射強度と所定の閾値とを比較し、反射強度が所定の閾値未満であれば、梢端におけるパラゴムノキは罹病していないと判定し、反射強度が所定の閾値以上であれば、梢端におけるパラゴムノキは罹病していると判定する判定工程とを備える。【選択図】図4
