Detecting tents to estimate the displaced populations for post-disaster relief using high resolution satellite imagery

• An automated method is addressed to generate a camp map from high resolution satellite imagery.
• The method is especially useful in detecting objects which have a clear shape, size, and spectral contrast.
• The overall accuracy can be up to 81% in this study.
• The performance is impacted by spectral characteristics of satellite sensors and image scenes.
• It is expected that the image scene would have a much higher influence on the performance than the sensor characteristics.

Estimating the number of refugees and internally displaced persons is important for planning and managing an efficient relief operation following disasters and conflicts. Accurate estimates of refugee numbers can be inferred from the number of tents. Extracting tents from high-resolution satellite imagery has recently been suggested. However, it is still a significant challenge to extract tents automatically and reliably from remote sensing imagery. This paper describes a novel automated method, which is based on mathematical morphology, to generate a camp map to estimate the refugee numbers by counting tents on the camp map. The method is especially useful in detecting objects with a clear shape, size, and significant spectral contrast with their surroundings. Results for two study sites with different satellite sensors and different spatial resolutions demonstrate that the method achieves good performance in detecting tents. The overall accuracy can be up to 81% in this study. Further improvements should be possible if over-identified isolated single pixel objects can be filtered. The performance of the method is impacted by spectral characteristics of satellite sensors and image scenes, such as the extent of area of interest and the spatial arrangement of tents. It is expected that the image scene would have a much higher influence on the performance of the method than the sensor characteristics.