Faith Njoki Karanja

Dr. Faith Njoki Karanja

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Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 August 2024 in Remote Sensing
Verified
Journal Article
Open access
PDF file
IOIan A. Ocholla
Ian A. Ocholla
Petri PellikkaPetri Pellikka
Petri Pellikka
FKFaith Njoki Karanja
Faith Njoki Karanja
IVIlja Vuorinne
Ilja Vuorinne
TVTuomas Väisänen
Tuomas Väisänen
JHJanne Heiskanen
Janne Heiskanen
Accurate livestock counts are essential for effective pastureland management. High spatial resolution remote sensing, coupled with deep learning, has shown promising results in livestock detection. However, challenges persist, particularly when the targets are small and in a heterogeneous environment, such as those in African rangelands. This study evaluated nine state-of-the-art object detection models, four variants each from YOLOv5 and YOLOv8, and Faster R-CNN, for detecting cattle in 10 cm resolution aerial RGB imagery in Kenya. The experiment involved 1039 images with 9641 labels for training from sites with varying land cover characteristics. The trained models were evaluated on 277 images and 2642 labels in the test dataset, and their performance was compared using Precision, Recall, and Average Precision (AP0.5–0.95). The results indicated that reduced spatial resolution, dense shrub cover, and shadows diminish the model’s ability to distinguish cattle from the background. The YOLOv8m architecture achieved the best AP0.5–0.95 accuracy of 39.6% with Precision and Recall of 91.0% and 83.4%, respectively. Despite its superior performance, YOLOv8m had the highest counting error of −8%. By contrast, YOLOv5m with AP0.5–0.95 of 39.3% attained the most accurate cattle count with RMSE of 1.3 and R2 of 0.98 for variable cattle herd densities. These results highlight that a model with high AP0.5–0.95 detection accuracy may struggle with counting cattle accurately. Nevertheless, these findings suggest the potential to upscale aerial-imagery-trained object detection models to satellite imagery for conducting cattle censuses over large areas. In addition, accurate cattle counts will support sustainable pastureland management by ensuring stock numbers do not exceed the forage available for grazing, thereby mitigating overgrazing.



30 September 2024 in Remote Sensing
Verified
Journal Article
Open access
PDF file
IOIan A. Ocholla
Ian A. Ocholla
Petri PellikkaPetri Pellikka
Petri Pellikka
FKFaith Njoki Karanja
Faith Njoki Karanja
IVIlja Vuorinne
Ilja Vuorinne
TVTuomas Väisänen
Tuomas Väisänen
JHJanne Heiskanen
Janne Heiskanen
The authors would like to make the following corrections to their published paper


20 October 2025
Verified
Book Chapter
Open access
AMAdelina Maria Mensah
Adelina Maria Mensah
FKFaith Njoki Karanja
Faith Njoki Karanja
CTCynthia Addoquaye Tagoe
Cynthia Addoquaye Tagoe
ABAdwoa Owusuaa Bobie
Adwoa Owusuaa Bobie
CWCharlotte Wrigley-Asante
Charlotte Wrigley-Asante
BMBetsy Makena Mugo
Betsy Makena Mugo