How to get rid of that vertical space between caption titles? (space between the second line and the third line).
The figures come from different files that have been \input'ted ; using \include does not change result.
Edit: problem is due to figures being in different chapters, not due to coming from different files. So answer is there. Thank you Werner.

Minimal example is
\documentclass[12pt,letterpaper,oneside]{book}
\usepackage{blindtext}
%\usepackage{tocloft}
%\usepackage[nottoc]{tocbibind}
%\usepackage{chngcntr}
%\counterwithout{figure}{chapter}
%\usepackage[labelsep=newline,justification=centering]{caption}
\begin{document}
\listoffigures
\input{part1.tex}
\input{part2.tex}
\end{document}
where part1.tex has two figures and is
\blinddocument
\begin{figure}
\begin{center}
\end{center}
\caption{First input file, first figure}
\label{fig:TrueDistances1}
\end{figure}
\begin{figure}
\begin{center}
\end{center}
\caption{First input file, second figure}
\label{fig:TrueDistances2}
\end{figure}
while part2.tex is
\blinddocument
\begin{figure}
\begin{center}
\end{center}
\caption{Second input file, first figure}
\label{fig:TrueDistances3}
\end{figure}