Appearance Label Balanced Triplet Loss for Multi-modal Aerial View Object Classification

Automatic target recognition (ATR) using image data is an important computer vision task with widespread applications in remote sensing for surveillance, object tracking, urban planning, agriculture, and more. Although there have been continuous advancements in this task, there is still significant room for further advancements, particularly with aerial images. This work extracts rich information from multimodal synthetic aperture radar (SAR) and electro-optical (EO) aerial images to perform object classification. Compared to EO images, the advantages of SAR images are that they can be captured at night and in any weather condition. Compared to EO images, the disadvantage of SAR images is that they are noisy. Overcoming the noise inherent to SAR images is a challenging, but worthwhile, task because of the additional information SAR images provide the model. This work proposes a training strategy that involves the creation of appearance labels to generate triplet pairs for training the network with both triplet loss and cross-entropy loss. During the development phase of the 2023 Perception Beyond Visual Spectrum (PBVS) Multi-modal Aerial Image Object Classification (MAVOC) challenge, our ResNet-34 model achieved a top-1 accuracy of 64.29% for Track 1 and our ensemble learning model achieved a top-1 accuracy 75.84% for Track 2. These values are 542% and 247% higher than the baseline values. Overall, this work ranked 3rd in both Track 1 and Track 2.