beamergraphicsoverlays
I would that the images would appeared for each overlay. Eg, in overlay 1 I have img1.pdf, in overlay 2 I have img2.pdf, and in overlay 3 I have img3.pdf. How I do this?
\begin{center}
\begin{tikzpicture}
\node (img1) {\includegraphics[width=.5\linewidth]{img1.pdf}};
\pause
\node (img2) {\includegraphics[width=.5\linewidth]{img2.pdf}};
\pause
\node (img3) {\includegraphics[width=.5\linewidth]{img3.pdf}};
\end{tikzpicture}
\end{center}
Two problems with your first attempt:
overlay keyword. Probably you wrote it because you wanted to overlay two figures, but that's not the purpose of this keyword. Inside a single tikzpicture all what you draw is indeed overlayed, by the order in which you draw things. The keyword is used when you want a tikzpicture to be overlayed on the surrounding text or in another tikzpictures, which is not the case.
In this example, overlay was the culprit of the bad positioning of the captioning, because overlay makes the figure to "disappear" at the eyes of TeX (it gives zero size to the figure).
Positioning of figure B inside figure A. By default, the coordinates of a node refer to its center. You have to use anchor=south east to make them refer to the lower left corner, as in the overpic example. You also need inner sep=0pt to remove the inner padding of the nodes containing the figures.
In addition, there is another problem with the coordinate units. overpic uses units relative to the scale. So in this case the amount 3 means 3% of the figure A width. This is a bit complex to achieve in tikz, and I think it is not required for this case. You can manually adjust the units used by tikz, using keywords x=dimension and y=dimension. Using 1mm produces roughly the same result than in your overpic example.
So the final code is:
\documentclass[12pt]{article}
\usepackage{mwe,tikz}\usepackage[percent]{overpic}
\pagestyle{empty}
\begin{document}
\begin{figure}
\centering
\begin{overpic}[scale=0.75]{example-image-a}
\put(3,3){\includegraphics[scale=0.21]{example-image-b}}
\end{overpic}
\caption{Using Overpic}
\end{figure}
\begin{figure} \centering
\begin{tikzpicture}[
every node/.style={anchor=south west,inner sep=0pt},
x=1mm, y=1mm,
]
\node (fig1) at (0,0)
{\includegraphics[scale=0.75]{example-image-a}};
\node (fig2) at (3,3)
{\includegraphics[scale=0.21]{example-image-b}};
\end{tikzpicture}
\caption{Using Tikz Overlay}
\end{figure}
\end{document}
If one wants to have the images to be of width \linewidth, one can issue the following code in the main Tex document:
\documentclass{minimal}
\usepackage{graphicx, color}
\begin{document}
\def\svgwidth{\linewidth}
\input{filename.pdf_tex}
\end{document}
Then, one needs to adapt the code of the file filename.pdf_tex in e.g. the following manner:
\put(0,0){\includegraphics and which contains {filename.pdf}.\put(0,0){\includegraphics[width=\linewidth]{another-image.jpg}}
Then, one can always scale the images further jointly, and re-position them jointly in the main document; e.g. by issuing them within e.g. a parbox-, minipage- and/or figure-environment.
Best Answer
\node(as well as all TikZ paths) is overlay-aware so you can useA complete example:
An animation of the result:
With your numbering schema you can use a loop: