Forums > Jitter

Create a light sensitive camera switch

February 22, 2008 | 7:22 pm

Hello all

This is my first proper venture into electronics so I am only at a very basic level. I am trying to make a simple camera that is triggered when it sees light – or at least when a light dependant resistor sees light. Can someone tell me How do I do it? and what else I need? I can do it with a webcam (preferably one built inrto a mac) and arduino board (if nessesary) to show the concept.


February 22, 2008 | 7:44 pm

On Fri, Feb 22, 2008 at 7:22 PM, Mr D wrote:

>
> This is my first proper venture into electronics so I am only at a very
> basic level. I am trying to make a simple camera that is triggered when it
> sees light – or at least when a light dependant resistor sees light. Can
> someone tell me How do I do it? and what else I need? I can do it with a
> webcam (preferably one built inrto a mac) and arduino board (if nessesary)
> to show the concept.

What do you mean exactly by triggered? Do you want to start recording video
when light come in above a certain treshold? Do you want to trigger some
hardware component on your Arduino board? Something in a Jitter patch?

Thijs


February 22, 2008 | 8:01 pm

We have been asked to communicate a concept for a camera at college. The my concept is of camera in an envelope that takes a still picture as the person flicks through a pile of envelopes.

It only needs to be really crude at this stage cause I have a crit on tuesday – so it would be acceptable to in someway use a webcam, as I would imagine its is most simple way to exicute a camera that has a light sisitive trigger for still images as it is alreday integrated into the computer.


February 23, 2008 | 2:14 am

hi,
i udnerstand you need a patch that.

grab video and turn to greyscale
detect brightest pixel value using jit.3m
if mean goes over defined limit, tirgger something

On Fri, Feb 22, 2008 at 10:01 PM, Mr D wrote:

>
> We have been asked to communicate a concept for a camera at college. The
> my concept is of camera in an envelope that takes a still picture as the
> person flicks through a pile of envelopes.
>
> It only needs to be really crude at this stage cause I have a crit on
> tuesday – so it would be acceptable to in someway use a webcam, as I would
> imagine its is most simple way to exicute a camera that has a light sisitive
> trigger for still images as it is alreday integrated into the computer.
>


February 23, 2008 | 12:41 pm

basically I want the light dependent resistor to turn the camera on, and hopefully take a still if possible. the final prototype will be an independent object but for the crit its ok to have it liked to a computer.


February 23, 2008 | 1:27 pm

On Sat, Feb 23, 2008 at 12:41 PM, Mr D wrote:

>
> basically I want the light dependent resistor to turn the camera on, and
> hopefully take a still if possible. the final prototype will be an
> independent object but for the crit its ok to have it liked to a computer.
>
>
Using just jitter for this would be very straightforward since you can leave
the camera on and let it work as your "light dependent resistor" to detect
and trigger its own recording, like Yair described.
Either you use Jitter, or electronics, but it doesn’t seem very logical to
combine the two. If you’re going for the second option you’re probably
better off mailing to a list with people that understand a lot about
electronics. I won’t be of much help, that’s for sure;-) Where is your still
going if you’re not using a computer in the final prototype?

Thijs


February 23, 2008 | 2:43 pm

This is still the case, I presume?

Lars

> Jitter does not currently support any "boned" or parametric model
> format. Instead it only supports the already tesselated polygon
> format option for .OBJ. So there are no "control" points, however you
> can manipulate the vertices by some formula if you wish either using
> matrixoutput or by using a vertex shader on the GPU.
>
> -Joshua


February 23, 2008 | 4:04 pm

Haven’t got that far yet but I would imagine the still will go in a usb stick or somthing?


February 23, 2008 | 5:43 pm

doing it without pc

http://www.riccibitti.com/witnesscam/entry/witnesscam.htm
a formidable DIY solution.

http://scratchpad.wikia.com/wiki/CHDK
another fine hack can be made using the CHDK firmware for the canon
powershot family.
aside from "histogram based motion detection" you can also trigger shooting
via the usb cable.
worth checking out.

dont forget to add us to your bibliography ;)

On Sat, Feb 23, 2008 at 6:04 PM, Mr D wrote:

>
> Haven’t got that far yet but I would imagine the still will go in a usb
> stick or somthing?
>


February 23, 2008 | 5:46 pm

no its not.
check http://jitogre.org/wiki/index.php5?title=Main_Page

On Sat, Feb 23, 2008 at 4:43 PM, Lars Graugaard
wrote:

> This is still the case, I presume?
>
> Lars
>
> > Jitter does not currently support any "boned" or parametric model
> > format. Instead it only supports the already tesselated polygon
> > format option for .OBJ. So there are no "control" points, however you
> > can manipulate the vertices by some formula if you wish either using
> > matrixoutput or by using a vertex shader on the GPU.
> >
> > -Joshua
>


February 23, 2008 | 11:06 pm

Very nice – great object, brilliant!

Everything works fine, except that I weren’t able to get the
OgreXMLConverter to work, getting this from the terminal:

/Applications/MaxMSP/3rd_party/ogre_download/OgreXMLConverter
test_export.mesh

– OPTIONS –
source file = test_export.mesh
destination file = test_export.mesh.xml
log file = OgreXMLConverter.log
interactive mode = false
lod levels = none (or use existing)
Generate edge lists = 1
Generate tangents = 0
Reorganise vertex buffers = 1
Optimise animations = 1
– END OPTIONS –

Creating resource group General
Creating resource group Internal
Creating resource group Autodetect
Registering ResourceManager for type Mesh
Registering ResourceManager for type Material
Registering ResourceManager for type Skeleton
terminate called after throwing an instance of
‘Ogre::InvalidParametersException’
what(): OGRE EXCEPTION(2:InvalidParametersException): Can only
determine the endianness of the input stream if it is at the start in
Serializer::determineEndianness at
/Developer/UserDev/ogrenew/Mac/Ogre/../../OgreMain/src/OgreSerializer.cpp
(line 63)
Abort trap

Any ideas?

I’m on mac 10.5.2 max 4.6.3 jitter 1.6.3

Lars


February 24, 2008 | 1:00 am

funny you should mention that as i’ve just updated the exporter.
hopefully this will fix your problems:

http://jitogre.org/OgreXMLConverter.dmg

i’ve also recently updated the maya exporter for the mac.
you should re-download that (if you’re using maya) because i fixed a bug when exporting .skeleton files.

http://jitogre.org/ogreMayaExporter_maya8.5_OSX.zip

let me know how everything works out for you, as i haven’t heard much feedback from folks using this yet.

-rob


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