something else resolved now ;
id forgotten to consider how im to preview the shot the cameras are getting during setup. so I did a little investigating to see what is possible.
I arrived at a solution with a bit of fiddling around, which works out pretty nice.
there is a package called "motion" available to install ;
sudo apt-get install motion
This is quite a clever application and can be set up to do a lot of stuff to do with camera's, timelapse, motion detection, tracking etc etc. looks like it would be a good thing for some kind of advanced security stuff. anyway we only need it for one of its features, ability to serve webcam video over the network. There is some setup needed, modifying of configuration files for the number and name of the cameras you are using. Rather than copy'n'paste all bits of code here I'll find a way later to make the config files available (you'd be able to pull them directly on the pi and put them in the right places).
So motion was setup for the two web-cams , and when I got it right, I could visit a page in firefox from another machine ipaddress:8081 for the first cam , ipaddress:8082 for the second cam.
Took a while longer to figure out how to get the pi camera working in the same way. there is a specific build of motion called motion-mmalcam , it works with the pi-cam. I tried to utilise this vers and get both the webcams running under it (that how it ought to work normally) , but no luck.
Still, this did not matter much, I now start the motion-mmal server to give the pi cam video on port 8081 , and the standard motion server to provide the webcam streams on ports 8082 and 8083.
Now I don't want these streams available all the time, plus they chew up some of the pi's resources. so I enable these servers only when the system has been put in PAUSE MODE. This mode is used when you need to get in there and do something and don't want to be in the timelapse !
It will also work as a setup mode now, so when you enter pause mode, the camera streaming is enabled, and when you return to RUN MODE, the streaming is disabled and stopped.
Took some more tinkering with the monitor script and this now seems to work really well.
I think that's most of the key functions sorted now, few nice to have as well. capture script will take a few days to get right I imagine, almost there. then there was that old idea of getting this thing to pan out by itself. kind of threw out the idea a week back but Its been consuming my thoughts again in the last day or two.
linear slide of some kind... maybe the pi pulls itself up the rail with a little winch driven off a geared stepper?
or thinking a bit laterally .... the undercarriage assembly off a "for parts" RC tank , suitable adjusted drive to allow a very sloooow and accurate movement. (we talking about receding smoothly away from the plant by about 6 foot over about 3 MONTHS !!!!
hmmm...