WRF.md Paraview documentation

WRF.md

@@ -631,6 +631,8 @@ For 3D visualization of WRF output, it is recommended to use either [Paraview](h
 
 ##### Paraview workflow
 
+1. Pre-requisite: [download](https://www.paraview.org/download/) and install the Paraview application on your computer.
+
 1. Log in to VSC5 in a terminal window.
 
 1. On VSC5, convert the WRF output in a format that Paraview can ingest. One option is to use [siso](https://github.com/TheBB/SISO).
@@ -683,7 +685,7 @@ Not tested yet.
 
 ##### Creating a video
 
-Whether done with Paraview or with Mayavi, the visualization will result in a collection of png files, e.g., `InnValley.%04d.png`. There are several tools to convert invidual frames into movies. Among them, `ffmpeg` and `apngasm`.
+Whether done with Paraview or with Mayavi, the visualization will result in a collection of png files, e.g., `InnValley.%04d.png`. There are several tools to convert invidual frames into movies. Among them, `ffmpeg` and `apngasm`. At the moment neither of them is available on IMGW servers (precompiled binaries are available through `apt-get` for Ubuntu).
 
 The basic method to create an `mp4` movie is:
 ```sh
@@ -722,7 +724,7 @@ It also possible to generate movies in other formats, better suited for the web:
     ffmpeg -framerate 12 -i InnValley.%04d.png InnValley.gif
     ```
 
-* To get a feeling of the file sizes:
+* For the example dataset, the collection of raw png files takes 59 MB while the video file sizes range between 4.5 and 70 MB:
     ```sh
     (mypy39) stefano@stefano-XPS-13-9370:~/Desktop/Paraview_animation/anim$ du -hcs InnValley.0*png
     59M	total