CloudSatNet-1: FPGA-based Hardware-Accelerated Quantized CNN for
Satellite On-Board Cloud Coverage Classification
Abstract
CubeSats, the nanosatellites with a wet mass up to 10 kg, accompanied by
the cost decrease of accessing the space, amplified the rapid
development of the Earth Observation industry. Acquired image data serve
as an essential source of information in various disciplines like
environmental protection, geosciences, or the military. As the quantity
of remote sensing data grows, the bandwidth resources for the data
transmission (downlink) are exhausted. Therefore, new techniques that
reduce the downlink utilization of the satellites must be investigated
and developed. For that reason, we are presenting CloudSatNet-1: an FPGA
based hardware-accelerated quantized convolutional neural network (CNN)
for satellite on-board cloud coverage classification. We aim to explore
the effects of the quantization process on the proposed CNN
architecture. Additionally, the performance of cloud coverage
classification by biomes diversity is investigated, and the hardware
architecture design space is explored to identify the optimal FPGA
resource utilization. Results of this study showed that the weights and
activations quantization adds a minor effect on the model performance.
Nevertheless, the memory footprint reduction allows the model deployment
on low-cost FPGA Xilinx Zynq-7020. Using the RGB bands only, up to 90%
of accuracy was achieved, and when omitting the tiles with snow and ice,
the performance increased up to 94.4% of accuracy with a low
false-positive rate of 2.23% for the 4-bit width model. With the
maximum parallelization settings, the hardware accelerator achieved 15
FPS with 2.5W of average power consumption (0.2W increase over the idle
state).