为什么这些多个子图的放置位置这么糟糕？

Question

我有这样的代码，我将 4 个地块放在两个figure*块中：

\subsection{Encoders Evaluation}
\begin{figure*}
    \centering
    \begin{subfigure}[b]{0.49\textwidth}
        \includegraphics[width=\textwidth]{Figures/mapVLADvsFV.png}
        \caption{}
        \label{fig:mapVLADvsFV}
    \end{subfigure}
    \begin{subfigure}[b]{0.49\textwidth}
        \includegraphics[width=\textwidth]{Figures/timesVLADvsFV.png}
        \caption{}
        \label{fig:timesVLADvsFV}
    \end{subfigure}
    \caption{VLAD and FV comparison. Figure \ref{fig:mapVLADvsFV} shows precision of the two encoding techniques, while Figure \ref{fig:descTimes} shows their efficiency.}\label{fig:PHA}
\end{figure*}
\begin{figure*}
    \centering
    \begin{subfigure}[b]{0.49\textwidth}
        \includegraphics[width=\textwidth]{Figures/VLADCenters.png}
        \caption{}
        \label{fig:VLADCenters}
    \end{subfigure}
    \begin{subfigure}[b]{0.49\textwidth}
        \includegraphics[width=\textwidth]{Figures/VLADTimes.png}
        \caption{}
        \label{fig:VLADTimes}
    \end{subfigure}
    \caption{VLAD results depending on the number of centers and descriptors used. Figure \ref{fig:VLADCenters} shows the precision of SURF and PHA, while Figure \ref{fig:descTimes} shows the efficiency of each descriptor..}\label{fig:PHA}
\end{figure*}

然而，这些图与其他几张图一起放在了2页之后...为什么会发生这种情况？

这是结果文档中这些图表的图片：

Answer 1

[t]只需向环境添加选项figure*：

\documentclass[twocolumn]{article}
\usepackage[demo]{graphicx}
\usepackage{caption}
\usepackage{subcaption}

\usepackage{showframe}
\usepackage{lipsum}
\begin{document}
\subsection{Encoders Evaluation}
\begin{figure*}[t]
\centering
\begin{subfigure}[b]{0.49\textwidth}
    \includegraphics[width=\textwidth]{Figures/mapVLADvsFV.png}
    \caption{}
    \label{fig:mapVLADvsFV}
\end{subfigure}\hfil
\begin{subfigure}[b]{0.49\linewidth}
    \includegraphics[width=\linewidth]{Figures/timesVLADvsFV.png}
    \caption{}
    \label{fig:timesVLADvsFV}
\end{subfigure}
\caption{VLAD and FV comparison. Figure \ref{fig:mapVLADvsFV} shows precision of the two encoding techniques, while Figure \ref{fig:descTimes} shows their efficiency.}
\label{fig:PHA}
\end{figure*}      % you can omit this and next line
\begin{figure*}[t] % you can omit this line
\begin{subfigure}[b]{0.49\linewidth}
    \includegraphics[width=\linewidth]{Figures/VLADCenters.png}
    \caption{}
    \label{fig:VLADCenters}
\end{subfigure}\hfil
\begin{subfigure}[b]{0.49\linewidth}
    \includegraphics[width=\linewidth]{Figures/VLADTimes.png}
    \caption{}
    \label{fig:VLADTimes}
\end{subfigure}
\caption{VLAD results depending on the number of centers and descriptors used. Figure \ref{fig:VLADCenters} shows the precision of SURF and PHA, while Figure \ref{fig:descTimes} shows the efficiency of each descriptor..}
\label{fig:PHA}
\end{figure*}
\lipsum\lipsum
\end{document}