| Summary: | Thesis (MSc)--Stellenbosch University, 2015. === ENGLISH ABSTRACT: In South Africa, black-back jackal (BBJ) predation of sheep causes heavy losses to sheep
farmers. Different control measures such as shooting, gin-traps and poisoning have been used
to control the jackal population; however, these techniques also kill many harmless animals,
as they fail to differentiate between BBJ and harmless animals. In this project, a system is
implemented to detect black-backed jackal faces in images. The system was implemented using
the Viola-Jones object detection algorithm. This algorithm was originally developed to detect
human faces, but can also be used to detect a variety of other objects. The three important
key features of the Viola-Jones algorithm are the representation of an image as a so-called
”integral image”, the use of the Adaboost boosting algorithm for feature selection, and the use
of a cascade of classifiers to reduce false alarms.
In this project, Python code has been developed to extract the Haar-features from BBJ
images by acting as a classifier to distinguish between a BBJ and the background. Furthermore,
the feature selection is done using the Asymboost instead of the Adaboost algorithm so as to
achieve a high detection rate and low false positive rate. A cascade of strong classifiers is trained
using a cascade learning algorithm. The inclusion of a special fifth feature Haar feature, adapted
to the relative spacing of the jackal’s eyes, improves accuracy further. The final system detects
78% of the jackal faces, while only 0.006% of other image frames are wrongly identified as faces. === AFRIKAANSE OPSOMMING: Swartrugjakkalse veroorsaak swaar vee-verliese in Suid Afrika. Teenmaatreels soos jag,
slagysters en vergiftiging word algemeen gebruik, maar is nie selektief genoeg nie en dood dus
ook vele nie-teiken spesies. In hierdie projek is ’n stelsel ontwikkel om swartrugjakkals gesigte
te vind op statiese beelde. Die Viola-Jones deteksie algoritme, aanvanklik ontwikkel vir die
deteksie van mens-gesigte, is hiervoor gebruik. Drie sleutel-aspekte van hierdie algoritme is die
voorstelling van ’n beeld deur middel van ’n sogenaamde integraalbeeld, die gebruik van die
”Adaboost” algoritme om gepaste kenmerke te selekteer, en die gebruik van ’n kaskade van
klassifiseerders om vals-alarm tempos te verlaag.
In hierdie projek is Python kode ontwikkel om die nuttigste ”Haar”-kenmerke vir die deteksie
van dié jakkalse te onttrek. Eksperimente is gedoen om die nuttigheid van die ”Asymboost”
algoritme met die van die ”Adaboost” algoritme te kontrasteer. ’n Kaskade van klassifiseerders
is vir beide van hierdie tegnieke afgerig en vergelyk. Die resultate toon dat die kenmerke wat die
”Asymboost” algoritme oplewer, tot laer vals-alarm tempos lei. Die byvoeging van ’n spesiale
vyfde tipe Haar-kenmerk, wat aangepas is by die relatiewe spasieëring van die jakkals se oë,
verhoog die akkuraatheid verder. Die uiteindelike stelsel vind 78% van die gesigte terwyl slegs
0.006% ander beeld-raampies verkeerdelik as gesigte geklassifiseer word.
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