• Nurul Amira Mohd Ramli Faculty of Electrical Engineering and Technology, Universiti Malaysia Perlis, Pauh Putra Campus, 02600, Arau, Perlis, Malaysia
  • Mohd Hafiz Fazalul Rahiman ᵃFaculty of Electrical Engineering and Technology, Universiti Malaysia Perlis, Pauh Putra Campus, 02600, Arau, Perlis, Malaysia ᵇCentre of Excellence for Advanced Sensor Technology, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia
  • Ruzairi Abdul Rahim Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat Johor, Malaysia
  • Latifah Munirah Kamarudin ᵇCentre of Excellence for Advanced Sensor Technology, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia ᵈFaculty of Electronic Engineering and Technology, Universiti Malaysia Perlis, Pauh Putra Campus, 02600, Arau, Perlis, Malaysia
  • Latifah Mohamed ᵃFaculty of Electrical Engineering and Technology, Universiti Malaysia Perlis, Pauh Putra Campus, 02600, Arau, Perlis, Malaysia ᵇCentre of Excellence for Advanced Sensor Technology, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia
  • Ammar Zakaria ᵃFaculty of Electrical Engineering and Technology, Universiti Malaysia Perlis, Pauh Putra Campus, 02600, Arau, Perlis, Malaysia ᵇCentre of Excellence for Advanced Sensor Technology, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia
  • Mohammed Saeed Moqbel Abdullah Faculty of Electrical Engineering and Technology, Universiti Malaysia Perlis, Pauh Putra Campus, 02600, Arau, Perlis, Malaysia



Image reconstruction, radio tomography, received signal strength, grain moisture sensing, moisture measurement


Inefficient storage of paddy and rice grains can lead to grain deterioration, resulting in post-harvest losses ranging from 10% to 30%. The quality of grains cannot be improved throughout the storage period. Therefore, following the mechanisation of agricultural industries, air dryers have been developed to control the crops’ moisture level by blowing ambient or heated air into the silo to improve the aeration and allow the grains to be preserved with minimal loss of quality until the appropriate time for managing and marketing processes. However, the conventional sampling method used to measure the moisture level is inefficient because it is very localised and only represents part of the moisture distribution inside the bulk grains. Additionally, incorporating advanced technologies can be a significant cost limitation for small-scale industries. Thus, to address the issue, this research study developed a radio tomographic imaging (RTI) system in a silo-scale prototype using 20 sensor nodes operating at 2.4 GHz to localise and monitor the moisture level constructively. The RTI system reconstructs the cross-sectional images across the rice silo by measuring radio frequency attenuation, in terms of received signal strength (RSS) quality, caused by the rice moisture phantoms within the wireless sensor network (WSN) area. A total of five phantoms’ profiles having a percentage of moisture content (MC) of 15%, 20% and 25% were reconstructed using four image reconstruction algorithms, Linear Back Projection (LBP), Filtered Back Projection (FBP), Newton’s One-step Error Reconstruction (NOSER) and Tikhonov Regularisation. 


Kumar, S. and K. Prasad. 2018. Effect of Parboiling and Puffing Processes on the Physicochemical, Functional, Optical, Pasting, Thermal, Textural and Structural Properties of Selected Indica Rice. Journal of Food Measurement and Characterization. 12(3): 1707-1722.

You, K. Y., L. L. You, C. S. Yue, K. Mun, C. S. Yue, H. K. Mun and C. Y. Lee. 2017. Physical and Chemical Characterization of Rice using Microwave and Laboratory Methods. In Rice - Technol. Prod., Amanullah, S. Fahad, eds. 1st ed. InTech. 81-99.

Müller, A., M. T. Nunes, V. Maldaner, P. C. Coradi, R. S. de Moraes, S. Martens, A. F. Leal, V. F. Pereira and C. K. Marin. 2022. Rice Drying, Storage and Processing: Effects of Post-harvest Operations on Grain Quality. Rice Science. 29(1): 16-30.

Alhendi, A. S., S. H. Al-Rawi and A. M. Jasim. 2019. Effect of Moisture Content of Two Paddy Varieties on the Physical and Cooked Properties of Produced Rice. Brazilian Journal of Food Technology. 22.

Naik, D. S. and M. B. Chetti. 2017. Influence of Packaging and Storage Conditions on the Moisture Content and Its Effect on Fungal Load of Paddy. Research Journal of Agricultural Sciences. 8(2): 370-374.

Shafiekhani, S., S. A. Wilson and G. G. Atungulu. 2018. Impacts of Storage Temperature and Rice Moisture Content on Color Characteristics qof Rice from Fields with Different Disease Management Practices. Journal of Stored Products Research. 78: 89-97.

Putri, R. E., A. Yahya, N. M. Adam and S. A. Aziz. 2015. Related Fracture Resistance with Moisture Content in Different Grain Orientation of Paddy Grain. Journal of Biology, Agriculture and Healthcare.11: 64-70.

Nelson, S. O. and S. Trabelsi. 2012. A Century of Grain and Seed Moisture Measurement by Sensing Electrical Properties. Transactions of the ASABE. 55(2): 629-636.

Edwards, K., N. Geddert, K. Krakalovich, R. Kruk, M. Asefi, J. Lovetri, C. Gilmore and I. Jeffrey. 2020. Stored Grain Inventory Management using Neural-network-based Parametric Electromagnetic Inversion. IEEE Access. 8: 207182-207192.

Nelson, S. O. 2015. Chapter 13 - Dielectric properties Models for Grain and SeedDielectr. Prop. Agric. Mater. Their Appl. Academic Press, ed. Elsevier Inc. 175-193.

Mazima, J. K., A. Johnson, E. Manasseh an. d S. Kaijage. 2018. An Overview of Electromagnetic Radiation in Grain Crops. International Journal of Food Science and Technology. 1(1): 21-32.

Nelson, S. O. 2015. Chapter 15 - Dielectric Properties Data. Elsevier Inc.

Nath K, D. and P. Ramanathan. 2017. Non-destructive Methods for the Measurement of Moisture Contents - A Review. Sensor Review. 37(1): 71-77.

Brisard, S., M. Serdar and P. J. M. Monteiro. 2020. Multiscale X-ray Tomography of Cementitious Materials: A Review. Cement and Concrete Research. 128(November 2019).

Tang, C. S., C. Zhu, T. Leng, B. Shi, Q. Cheng and H. Zeng, 2019. Three-dimensional Characterization of Desiccation Cracking Behavior of Compacted Clayey Soil using X-Ray Computed Tomography. Engineering Geology. 255(December 2018): 1-10.

Couceiro, J., O. Lindgren, L. Hansson, O. Söderström and D. Sandberg. 2019. Real-time Wood Moisture-content Determination using Dual-energy X-ray Computed Tomography Scanning. Wood Material Science and Engineering. 14(6): 437-444.

Rymarczyk, T., J. Sikora and P. Tchórzewski. 2018. Implementation of Electrical Impedance Tomography for Analysis of Building Moisture Conditions. COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering. 37(5): 1837-1861.

Jong, S. M. de, R. A. Heijenk, W. Nijland and M. van der Meijde. 2020. Monitoring Soil Moisture Dynamics using Electrical Resistivity Tomography under Homogeneous Field Conditions. Sensors (Switzerland). 20(18): 1-18.

Martin, L., H. Cochard, S. Mayr and E. Badel. 2021. Using Electrical Resistivity Tomography to Detect Wetwood and Estimate Moisture Content in Silver Fir (Abies alba Mill.). Annals of Forest Science. 78(3).

Rahman, N. A. A., L. E. Hong, R. A. Rahim, H. A. Rahim, N. Ahmad, S. Bunyamin, K. H. Abas, N. M. N. Ayob, F. R. M. Yunos and M. S. B. Mansor. 2015. A Review: Tomography Systems in Medical and Industrial Processes. Jurnal Teknologi. 73(6): 1-11.

Yao, J. and M. Takei. 2017. Application of Process Tomography to Multiphase Flow Measurement in Industrial and Biomedical Fields: A Review. IEEE Sensors Journal. 17(24): 8196-8205.

Mohd Ramli, N. A., M. H. Fazalul Rahiman, L. M. Kamarudin, L. Mohamed, A. Zakaria, A. Ahmad and R. A. Rahim. 2021. A New Method of Rice Moisture Content Determination using Voxel Weighting-based from Radio Tomography Images. Sensors (Basel, Switzerland). 21(11).

Rahiman, M. H. F. 2013. Ultrasonic Tomography System for Liquid / Gas Bubble Column. Universiti Teknologi Malaysia.

Wilson, J. and N. Patwari. 2010. Radio Tomographic Imaging with Wireless Networks. IEEE Transactions on Mobile Computing. 9(5): 621-632.

Erunkulu, O. O., A. M. Zungeru, C. K. Lebekwe and J. M. Chuma. 2020. Cellular Communications Coverage Prediction Techniques: A Survey and Comparison. IEEE Access. 8: 113052-113077.

Obeidat, H., A. Alabdullah, E. Elkhazmi, W. Suhaib, O. Obeidat, M. Alkhambashi, M. Mosleh, N. Ali, Y. Dama, Z. Abidin, R. Abd-Alhameed and P. Excell. 2020. Indoor Environment Propagation Review. Computer Science Review. 37: 100272.

Chiu, C. and D. Dujovne. 2014. Experimental Characterization of Radio Tomographic Imaging using Tikhonov’s Regularization. 2014 IEEE Biennial Congress of Argentina (ARGENCON). 468-472.

Kiat, T. T. W. 2017. Simulation Study of Tomography for Agarwood Evaluation. Universiti Malaysia Perlis.

Asefi, M., I. Jeffrey, J. LoVetri, C. Gilmore, P. Card and J. Paliwal. 2015. Grain Bin Monitoring via Electromagnetic Imaging. Computers and Electronics in Agriculture. 119: 133-141.

Postharvest Unit, C.,2013. Paddy Drying.

Azmi, N., L. M. Kamarudin, A. Zakaria, D. L. Ndzi, M. H. F. Rahiman, S. M. M. S. Zakaria and L. Mohamed. 2021. Rf-based Moisture Content Determination in Rice using Machine Learning Techniques. Sensors. 21(5): 1-20.

Almaleeh, A. A., A. Zakaria, L. M. Kamarudin, M. H. F. Rahiman, D. L. Ndzi and I. Ismail. 2022. Inline 3D Volumetric Measurement of Moisture Content in Rice using Regression-based ML of RF Tomographic Imaging. Sensors. 22(1).

Kazeem, O. O., O. O. Akintade and L. O. Kehinde. Comparative Study of Communication Interfaces for Sensors and Actuators in the Cloud of Internet of Things. International Journal of Internet of Things. 6(1): 9-13.

Shukri, S. and L. M. Kamarudin. 2017. Device Free Localization Technology for Human Detection and Counting with RF Sensor Networks: A Review. Journal of Network and Computer Applications. 97(October 2016): 157-174.

Wahab, Y. A., R. A. Rahim, M. H. F. Rahiman, S. Ridzuan Aw, F. R. M. Yunus, J. Puspanathan, N. M. N. Ayob, P. L. Leow, H. A. Rahim, I. L. Ahmad, A. Jonet, K. S. Chia and K. S. Tee. 2017. Inverse Problem: Comparison between Linear Back-projection Algorithm and Filtered Back-projection algorithm in Soft-field Tomography. International Journal of Integrated Engineering. 9(4): 32-36.

Goh, C .L., A. R. Ruzairi, F. R. Hafiz and Z. C. Tee. 2017. Ultrasonic Tomography System for Flow Monitoring: A Review. IEEE Sensors Journal. 17(17): 5382-5390.

Schofield, R., L. King, U. Tayal, I. Castellano, J. Stirrup, F. Pontana, J. Earls and E. Nicol. 2020. Image Reconstruction: Part 1 – Understanding Filtered Back Projection, Noise and Image Acquisition. Journal of Cardiovascular Computed Tomography. 14(3): 219-225.

Mallach, M., M. Gevers, P. Gebhardt and T. Musch. 2018. Fast and Precise Soft-field Electromagnetic Tomography Systems for Multiphase Flow Imaging. Energies 2018. 11(5): 1-17.

Mallach, M., P. Gebhardt and T. Musch. 2017. 2D Microwave Tomography System Metal Pipes. Flow Measurement and Instrumentation. 53(2017): 80-88.

Yunos, Y. M., R. A. Rahim, R. G. Green and M. H. F. Rahiman. 2007. Image Reconstruction using Iterative Transpose Algorithm for Optical Tomography. Jurnal Teknologi. 47(1): 91-102.

Cui, Z., Q. Wang, Q. Xue, W. Fan, L. Zhang, Z. Cao, B. Sun, H. Wang and W. Yang. 2016. A Review on Image Reconstruction Algorithms for Electrical Capacitance/Resistance Tomography. Sensor Review. 36(4): 429-445.

Guo, Q., X. Li, B. Hou, G. Mariethoz, M. Ye, W. Yang and Z. Liu. 2020. A Novel Image Reconstruction Strategy for ECT: Combining Two Algorithms with a Graph Cut Method. IEEE Transactions on Instrumentation and Measurement. 69(3): 804-814.

Beck, B., X. Ma and R. Baxley. 2016. Ultrawideband Tomographic Imaging in Uncalibrated Networks. IEEE Transactions on Wireless Communications. 15(9): 6474-6486.

Liedmann, F., C. Holewa and C. Wietfeld. 2018. The Radio Field as a Sensor-A Segmentation based Soil Moisture Sensing Approach. 2018 IEEE Sensors Applications Symposium, SAS 2018 - Proceedings. 2018-January: 1-6.

Mishra, P., C. M. Pandey, U. Singh, A. Gupta, C. Sahu and A. Keshri. 2019. Descriptive Statistics and Normality Tests for Statistical Data. Annals of Cardiac Anaesthesia. 22(1): 67-72.

Wang, Z., A. C. Bovik, H. R. Sheikh and E. P. Simoncelli. 2004. Image Quality Assessment: From Error Visibility to Structural Similarity. IEEE Transactions on Image Processing. 13(4): 600-611.

Banitalebi-Dehkordi, M., M. Khademi, A. Ebrahimi-Moghadam and H. Hadizadeh. 2019. An Image Quality Assessment Algorithm based on Saliency and Sparsity. Multimedia Tools and Applications. 78(9): 11507-11526.

Chang, P. C., K. Liang, J. C. Lim, M. C. Chung and L. Y. Chien. 2013. A Comparison of the Thresholding Strategies of Micro-CT for Periodontal Bone Loss: A Pilot Study. Dentomaxillofacial Radiology. 42(2).

Hoang, N. D 2018. Detection of Surface Crack in Building Structures using Image Processing Technique with an Improved Otsu Method for image Thresholding. Advances in Civil Engineering.

Saddami, K., P. Afrah, V. Mutiawani and F. Arnia. 2019. A New Adaptive Thresholding Technique for Binarizing Ancient Document. 1st 2018 Indonesian Association for Pattern Recognition International Conference, INAPR 2018 - Proceedings. 57-61.

Kurniadi, F. I., D. Septyani and I. S. Pratama. 2020. Local Adaptive Thresholding Techniques for Binarizing Scanned Lampung Aksara Document Images. 2020 3rd International Conference on Computer and Informatics Engineering, IC2IE 2020. 135-139.

Lee, S. W. 2022. Regression Analysis for Continuous Independent Variables in Medical Research: Statistical Standard and Guideline of Life Cycle Committee. Life Cycle. 2: 1-8.

Hope, T. M. H. 2019. Linear Regression. Mach. Learn. Methods Appl. to Brain Disord. Elsevier Inc. 67-81.






Science and Engineering

How to Cite