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Estimating the size of plants by using two parallel views
Barbara VIDEC, Jurij RAKUN
pp. 1-7
ABSTRACT
This paper presents a method of estimating the size of plants by using two parallel views of the scene, taken by a common digital camera. The approach relays on the principle of similar triangles with the following constraints: the resolution of the camera is known; the object is always in parallel to the camera sensor and the intermediate distance between the two concessive images is available. The approach was first calibrated and tested using one artificial object in a controlled environment. After that real examples were taken from agriculture, where we measured the distance and the size of a vine plant, apple and pear tree. By comparing the calculated values to measured values, we concluded that the average absolute error in distance was 0.11 m or around 3.7 %, and the absolute error in high was 0.09 m or 4.6 %.
Key words: digital image processing, size, digital camera, pixels, similar trianglesd
Slovenian:
Ocenjevanje velikosti rastlin s pomočjo dveh vzporednih pogledov
V delu je opisana metoda za ocenjevanje velikosti rastlin s pomočjo dveh vzporednih pogledov na isto sceno, zajetih s pomočjo digitalne kamere. Postopek temelji na principu podobnih trikotnikov z naslednjimi omejitvami: znani so podatki o ločljivosti uporabljene kamere; opazovani predmet je vedno vzporeden s senzorjem kamere; znan je podatek o vmesni razdalji med dvema korakoma zajema podatkov. Prvi korak v delu opisuje umerjanje metode ob pomoči umetnega predmeta v nadzorovanih pogojih. Drugi korak pa opisuje uporabo postopka na realnih primerih iz področja kmetijstva, kjer je bila ocenjena velikost vinske trte jablane in hruške. Ob primerjavi dobljenih podatkov z izmerjenimi je bilo ugotovljena absolutna napaka v razdalji do predmetov v velikosti 0,11 m, oz. 3,7 % glede na celotno oddaljenost, absolutna napaka v velikosti v obsegu 0,09 m oz. 4,6 %.
Ključne besede: digitalno procesiranje slik, velikost, digitalna kamera, slikovni elementi, podobni trikotniki
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