## 3 Digital Image Acquisition, Processing and Modelling Reconstruction
### Digital Image Acquisition Devices
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Imaging Techniques**} & \multirow{2}{*}{\begin{tabular}{c} **Aggregate Size** \\ **Range** \\ \end{tabular} } & \multicolumn{4}{c}{**Morphological Calculation Methods**} & \multirow{2}{*}{**Literatures**} \\ \cline{3-3} \cline{5-6}  & & **Shape** & & **Angularity** & **Texture** \\ \hline \multicolumn{2}{c}{Early digital imaging devices} & No.8-1-inch & Shape & - & - & [72] \\ \hline \multirow{4}{*}{\begin{tabular}{c} Dynamic \\ imaging techniques \\ \end{tabular} } & \multirow{2}{*}{VDG-40} & No.16 to & \multirow{2}{*}{Length and width} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & [74] \\ \cline{1-1}  & & 1.5 inch & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Dynamic \\ imaging techniques \\ \end{tabular} } & \multirow{2}{*}{CPA} & No.140 to & \multirow{2}{*}{Gradation and } & \multirow{2}{*}{-} & \multirow{2}{*}{-} & [75] \\ \cline{1-1}  & & 1.5 inch & & & & \\ \cline{1-1}  & & & & & \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Dynamic \\ imaging techniques \\ \end{tabular} } & \multirow{2}{*}{PSDA} & No.200 to & \multirow{2}{*}{Shape, and } & \multirow{2}{*}{-} & \multirow{2}{*}{-} & [76] \\ \cline{1-1}  & & 1.5 inch & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Characteristics of different imaging techniques. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Imaging Techniques**} & \multicolumn{2}{c}{**Aggregate Size**} & \multicolumn{4}{c}{**Morphological Calculation Methods**} & \multirow{2}{*}{**Literatures**} \\ \cline{3-4} \cline{6-6}  & **Range** & & **Shape** & **Angularity** & **Texture** & \\ \hline \multirow{5}{*}{Dynamic imaging techniques} & VIS & No.16 to & \multirow{2}{*}{Shape} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{[76]} \\  & 1.5 inch & & & & \\ \cline{2-6}  & PSSDA & No.200 to & \multirow{2}{*}{Grading} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{[76]} \\  & 1.5 inch & & & & \\ \cline{2-6}  & Camsizer & No.50 to & \multirow{2}{*}{Sphericity and aspect ratio} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{[45]} \\  & imaging techniques & & & & \\ \cline{2-6}  & WipShape & No.4 to 1.0 inch & \multirow{2}{*}{Grading and aspect ratio} & Minimum & \multirow{2}{*}{-} & \multirow{2}{*}{[77]} \\  & & & & & \\ \cline{2-6}  & WipShape & No.4 to 1.0 inch & & & & \\ \cline{2-6}  & UIAIA & No.4 to 1.5 inch & \multirow{2}{*}{Sphericity and aspect ratio} & Change of & \multirow{2}{*}{[78]} \\  & & & & & \\ \cline{2-6}  & LAAS & No.10 to & \multirow{2}{*}{Aspect ratio} & Wavelet method & [26] \\  & 4.0 inch & & & & \\ \cline{2-6}  & AIMS II & No.200 to & \multirow{2}{*}{Sphericity and aspect ratio} & Gradient & Wavelet & \multirow{2}{*}{[79]} \\  & 1.0 inch & & & & \\ \cline{2-6}  & FTI system & No.50 to & \multirow{2}{*}{Sphericity and aspect ratio} & Two-dimensional Fourier & \multirow{2}{*}{[80]} \\  & 0.75 inch & & & & transform method \\ \cline{2-6}  & PIAS & No.200 to & \multirow{2}{*}{Fast Fourier transform method} & [23] \\  & 1.0 inch & & & & \\ \cline{2-6}  & OSAAS & No.16 to & \multirow{2}{*}{Sphericity, aspect ratio, and Spherical Harmonic Series (SHS)} & \multirow{2}{*}{[81]} \\  & 5.0 inch & & & & \\ \cline{2-6}  & X-ray CT & No.200 to 5.0 & \multirow{2}{*}{Spherical Harmonic Series} & \multirow{2}{*}{[81]} \\  & & & & \\ \cline{2-6}  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._