Danish Institute of Agricultural SciencesHenning T. SøgaardDept of Agricultural EngineeringEmail: HenningT.Sogaard@agrsci.dk

A New ProjectA New Project

• Build and equip a small autonomous vehicle for mapping weed and crop parameters in the field

• Participants: DJF, AAU, KVL, private companies

• Project period: Nov 2000 - May 2003

Danish Institute of Agricultural SciencesHenning T. SøgaardDept of Agricultural EngineeringEmail: HenningT.Sogaard@agrsci.dk

A Computer Vision ProblemA Computer Vision Problemto be Solvedto be Solved

• Only weed plants without overlap• Weed plants from cotyledon stage until two foliage

leaves• Only a few selected weed species (< 20?)• Correct identification rate at same level as

reported by other researchers• Sampling scheme (not cover entire field)• Solution based on existing method if possible

Identification of weed species from digital (colour) images

Danish Institute of Agricultural SciencesHenning T. SøgaardDept of Agricultural EngineeringEmail: HenningT.Sogaard@agrsci.dk

Potential MethodsPotential Methods

• Leaf/plant shape (e.g. template matching, Fourier analysis of contour)

• Leaf texture (e.g. Fourier transform, wavelets)

• Leaf colour/reflection spectra (e.g. linear discriminant analysis)

Reported methods include recognition of

Danish Institute of Agricultural SciencesHenning T. SøgaardDept of Agricultural EngineeringEmail: HenningT.Sogaard@agrsci.dk

Representation of the Contour by a Representation of the Contour by a Fourier SeriesFourier Series

Fourier terms: N = 15

0

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0 2 4 6 8 10 12 14

Colour photo of cornflower at cotyledon stage

Contour and Fourier approx.

Danish Institute of Agricultural SciencesHenning T. SøgaardDept of Agricultural EngineeringEmail: HenningT.Sogaard@agrsci.dk

Classification based on Image Classification based on Image Database of Known Weed PlantsDatabase of Known Weed Plants

• Derive linear or quadratic discrimination functions by analysing images of known weed plants

• Compare feature vector of an unknown weed with feature vectors in a database of known weeds - e.g. by Mahalanobis distance measure

Danish Institute of Agricultural SciencesHenning T. SøgaardDept of Agricultural EngineeringEmail: HenningT.Sogaard@agrsci.dk

We are open to We are open to new ideas!new ideas!