Transparent soils provide an elegant and inexpensive method of visualizing 3D flow in a synthetic soil with a specific grain size distribution. The technology permits researchers to investigate the mechanism of multi-phase flow. When transparent soils are employed, one of the difficulties is optical noise within the model, which causes random variation in the value of the luminance (grayscale) component of the image. A methodology for 3D imaging of multi-phase liquid distribution was presented. The method employs color space analysis of orthogonal images acquired at the model boundaries.
The spatial volume was first estimated and then reconstructed at various stages of contamination and remediation. Chromatic families of color space are less sensitive to optical noise compared to luminance (grayscale) components. Thus, color space analysis was employed to segment the non-aqueous phase liquid (NAPL) zone and transform pixel information into integrated concentration values using a calibration model. The results show that the proposed reconstruction methodology provides better efficacy for NAPL zone reconstruction compared with conventional image analysis routines.
The following video presents a method for predicting positions of color cubes inside a square transparent solid object from images taken at the orthogonal boundary surfaces. Yellow transparent cubes are used to represent NAPL plumes and clear transparent cubes are used as representations of transparent soil in order to definitively validate the algorithm. Color space information is used to relate concentration and image intensity. The new algorithm employs a so-called 3D carving method to iteratively reconstruct a 3D model using images taken at three orthogonal boundaries. The methodology presented is a fast, relatively accurate, non-intrusive and inexpensive method for quantifying NAPL zones in transparent soil models.
Primary References
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