[K12OSN] Teacher Tool

Theo Turner Theo.Turner at CumnorHouse.com
Mon Mar 12 18:47:06 UTC 2007

Thanks, I now have this running (I admit on a windows box) using a batch
script that just loops. The pictures are then view through a web browser
as a thumbnail of each computer. The Webpage refreshes itself every few
seconds which updates the screenshots. The pictures are linked to a page
with the full size picture. Clicking on this launches the java web based
vnc viewer on the machine being viewed and the teacher can then control
the pc or just view it live. 

This all seems to work OK. One improvement I would like but don't know
how to do is to have the script recognize a failed snapshot (like when
the computer is switched off) and use a different standard image. Then
it could be clear at a glance that not all the PC's are on. This is
significant as when a PC is off it takes a lot longer attempting to
capture that screen. If several are off this adds a significant time lag
before the images a re all re-captured.

It's not a major problem but it would be nice. Having it web based is
very elegant as it works well on both windows and Linux clients even on
LTSP as the refresh rate is only every few seconds.


-----Original Message-----
From: k12osn-bounces at redhat.com [mailto:k12osn-bounces at redhat.com] On
Behalf Of Huck
Sent: 12 March 2007 18:43
To: Support list for open source software in schools.
Subject: Re: [K12OSN] Teacher Tool

or ImageMagik? http://www.imagemagick.org/script/index.php


Peter Scheie wrote:
> Robert Arkiletian wrote:
>> On 3/9/07, Peter Scheie <peter at scheie.homedns.org> wrote:
>>> Robert Arkiletian wrote:
>>> > On 3/8/07, Kemp, Levi <lnkemp at bolivar.k12.mo.us> wrote:
>>> >> Is there a way in teacher tool to monitor the screens of all the
>>> >> students, even if it is a smaller size? If not does anyone know
how I
>>> >
>>> > This seems to be a popular request but the only way I currently
>>> > how to do this is to simply set the -geometry option in the
>>> > call. I also could probably get the vnc windows to arrange
>>> > on screen not to overlap. But if the student desktop is 1024x768
>>> > each view window (on the teacher screen) is 320x200 (or something)
>>> > then you don't see the entire student desktop only a section (not
>>> > useful). Does anyone know of a way to scale a vnc session to
create a
>>> > thumbnail?
>>> >
>>> There's a package on freshmeat called VNC Snapshot that is a 
>>> commandline utility that
>>> takes a jpeg snapshot of a VNC server (the client machine in our 
>>> case).  Perhaps with
>>> that you could scale the jpegs down to thumbnail size and create a 
>>> 'board' with
>>> snapshots of the clients.  It's not real-time, but I think that's 
>>> probably better, as a
>>> bunch of real-time thumpnails would tax the network.  VNC Snapshot
is at
>>> http://vncsnapshot.sourceforge.net/
>> This is the best idea I have seen. Thanks Petre. You are right, real
>> time thumbs would probably be too much for the network. I will see if
>> I can integrate vnc snapshot. Might not happen till this summer as I
>> am bogged down with report cards and teaching.
> Further, you may want to have a look at jpgtn which generates
> from jpeg files.  See http://jpgtn.sourceforge.net/
> Petre
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