Manuel Zahn

2papers

2 Papers

CVApr 3, 2023
Efficient human-in-loop deep learning model training with iterative refinement and statistical result validation

Manuel Zahn, Douglas P. Perrin

Annotation and labeling of images are some of the biggest challenges in applying deep learning to medical data. Current processes are time and cost-intensive and, therefore, a limiting factor for the wide adoption of the technology. Additionally validating that measured performance improvements are significant is important to select the best model. In this paper, we demonstrate a method for creating segmentations, a necessary part of a data cleaning for ultrasound imaging machine learning pipelines. We propose a four-step method to leverage automatically generated training data and fast human visual checks to improve model accuracy while keeping the time/effort and cost low. We also showcase running experiments multiple times to allow the usage of statistical analysis. Poor quality automated ground truth data and quick visual inspections efficiently train an initial base model, which is refined using a small set of more expensive human-generated ground truth data. The method is demonstrated on a cardiac ultrasound segmentation task, removing background data, including static PHI. Significance is shown by running the experiments multiple times and using the student's t-test on the performance distributions. The initial segmentation accuracy of a simple thresholding algorithm of 92% was improved to 98%. The performance of models trained on complicated algorithms can be matched or beaten by pre-training with the poorer performing algorithms and a small quantity of high-quality data. The introduction of statistic significance analysis for deep learning models helps to validate the performance improvements measured. The method offers a cost-effective and fast approach to achieving high-accuracy models while minimizing the cost and effort of acquiring high-quality training data.

HCJan 12, 2022
Obstacle avoidance for blind people using a 3D camera and a haptic feedback sleeve

Manuel Zahn, Armaghan Ahmad Khan

Navigation and obstacle avoidance are some of the hardest tasks for the visually impaired. Recent research projects have proposed technological solutions to tackle this problem. So far most systems fail to provide multidimensional feedback while working under various lighting conditions. We present a novel obstacle avoidance system by combining a 3D camera with a haptic feedback sleeve. Our system uses the distance information of the camera and maps it onto a 2D vibration array on the forearm. In our functionality tests of the haptic feedback sleeve, users were able to correctly identify and localize 98,6% of single motor vibration patterns and 70% of multidirectional and multi-motor vibration patterns. The combined obstacle avoidance system was evaluated on a testing route in the dark, simulating a navigation task. All users were able to complete the task and showed performance improvement over multiple runs. The system is independent of lighting conditions and can be used indoors and outdoors. Therefore, the obstacle avoidance system demonstrates a promising approach towards using technology to enable more independence for the visually impaired.