HPWREN Camera Image Access and Download Overview

March 18, 2021

Images and videos seen on the various HPWREN camera sites, such as /cameras, are available to the public for download from our archives. The only requirement for their usage is to provide attribution to HPWREN (http://hpwren.ucsd.edu) if images are published. See /a_and_d.html for details.

The latest HPWREN camera images and videos are available in various display formats at

Recent collections of images and videos are found in the directory structure described in #2 below.

HPWREN servers capture, process, publish and archive images and videos around the clock (images are captured once per minute, videos every three hours). This data is collected from a few hundred camera image sources around San Diego, Imperial, and Orange County with new cameras being added regularly. Our archives are spread across multiple servers and we provide multiple tools for their access. Images are stored as jpg files and videos are stored as mp4 files. Our Archives data back to around 2000 with past images coalesced into (and replaced by) mp4 videos to reduce storage requirements. Those mp4 videos can be downloaded and from them the (very near) original jpg files can be re-extracted, if desired, using ffmpeg. This is most readily done on a Unix system (sample re-extraction command line: “ffmpeg -i Q4.mp4 -f image2 -qscale 0 -vcodec mjpeg Q4-%03d.jpg”) but ffmpeg is available on Windows as well. See an example perl script for recovering jpg images from our mp4 files in Appendix A at the end of this document.

HPWREN provides a number of mechanisms for users to search for, view, and if desired download single or multiple images and videos (in custom packaged zip files when larger amounts of data are requested). These tools include the following:

All the above tools are easier to use if you know the mapping of the camera names to the location. We have a guide for that at http://c1.hpwren.ucsd.edu/tools/camera-locations.txt (or in NextCloud named “Locating_HPWREN_images_and_videos.pdf”) which will list the locations of the cameras and, for cameras that are no longer active, the date they became inactive.

If you are interested in our cameras image return rates, we also have two tools available to show return rates for the previous 24 hours:

To see all image return rates, select "Summary" and click "Submit". You can also select individual cameras.

We hope you find these tools useful and encourage any feedback you may have for us at /contactForm4.html


Appendix A

Perl script example for recovering jpg images from mp4 files

The following perl script shows how to re-extract the original jpg files to their original (unix epoch data string) filenames. Assumes you downloaded mp4 file from http://c1.hpwren.ucsd.edu/archive/sp-s-mobo-c/large/2018/20180806/MP4/ and the index file from http://c1.hpwren.ucsd.edu/archive/sp-s-mobo-c/large/2018/20180806/Q4/ and placed them in local folder Q4:

  #!/usr/local/bin/perl
  
  # cd to target directory ... Q4
  
  $vname=$ARGV[0]; # e.g.: Q4.mp4
  $vdesc=$ARGV[1]; # e.g.: 20170708_syp-n-mobo-c_Q4-Source-file-ctime.txt
  
  if($vdesc !~ "ctime"){die("need proper parameters....");}
  open(I,"$vdesc") || die("Cannot open input file $vdesc");
  
  system("ffmpeg -i ../MP4/$vname -f image2 -qscale 0 -vcodec mjpeg %05d.jpg");
  
  while() {
   ($if,$ofname,@r)=split(" ",$_);
   rename("$if.jpg","$ofname");
  }
  close(I);