Images:

http://cds.cern.ch/record/1211045?ln=en
© 2009-2016 CERN (License: CC-BY-SA-4.0)
0910152_02-A4-at-144-dpi.jpg  
0910152_02-A5-at-72-dpi.jpg

http://cds.cern.ch/record/1606502?ln=en
eemm_run195099_evt137440354_ispy_3d-annotated-2.png
© 2012 CERN, for the benefit of the CMS Collaboration (License: CC-BY-SA-4.0)

Other info:
http://robjhyndman.com/hyndsight/beamer-poster/
https://github.com/deselaers/latex-beamerposter

Dimensions:

One column:

\begin{textblock}{78.0}(4,110)
\end{textblock}

Two columns:

 4                         2
<--><------- 38 --------><-><------- 38 ------->
|  |                      | |                   |
0  4                     42 44                  82

\begin{textblock}{38.0}(4,77)
\end{textblock}
\begin{textblock}{38.0}(44,77)
\end{textblock}

or three columns:

\begin{textblock}{24.0}(4,34)
\end{textblock}

\begin{textblock}{24.0}(30,34)
\end{textblock}

\begin{textblock}{24.0}(56,34)
\end{textblock}

or four columns:

84 -4 -4 -2 -2 -2 = 70 => 17.5 width

\begin{textblock}{17.5}(4,54)
\end{textblock}

\begin{textblock}{17.5}(23.5,54)
\end{textblock}

\begin{textblock}{17.5}(43,54)
\end{textblock}

\begin{textblock}{17.5}(62.5,54)
\end{textblock}