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Accurate dye tracer concentration estimations using image analysis

In English

Författare

Summary, in English

In this paper, the accuracy of dye tracer concentration estimations using image analysis is examined. The variability before and after application of different image correction methods was investigated in three experiments using a digital camera. In each of these experiments, one correction was applied and the remaining variability after correction was calculated as the SD of uniformly colored patches on color scale. Correction for inhomogeneous illumination results in relatively small remaining variability. The variability after correction for different color temperatures (or white point) was larger if the correction was made for image files directly from the camera. However, when using the raw data from the image sensor in the camera, the remaining variability was significantly reduced. A calibration experiment was also conducted, in which photographs of calibration samples of dye-stained soil were taken. Between 72 and 260 samples were prepared for each of three soils. The samples had dye concentrations from 0 to 1.5 g L-1. Effects of exposure settings and calibration model were investigated. The exposure settings only affected the results significantly in one soil which became dark when the dye concentration was high. Overexposure made the image lighter and the root mean square error (RMSE) of the concentration estimate decreased for this soil. By applying a neural network (NN) model, the RMSE of the dye concentration estimates could be as low as 0.0747 to 0.0944 g L-1. Reasonable accuracy (0.10-0.13 g L-1) could also be achieved with a polynomial calibration relationship derived from around 20 soil samples.

Publiceringsår

2005

Språk

Engelska

Sidor

967-975

Publikation/Tidskrift/Serie

Soil Science Society of America Journal

Volym

69

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

Soil Science Society of Americ

Ämne

  • Water Engineering

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0361-5995