Forum

Hardware for Tracking two Persons on a Stage

hi VVVVorum,

i am searching for the cheapest posibility to track two persons on stage (others will be on stage to).

i thought about IR-leds with different flashing rhythm and a cam with IR-filter.

an other solution may be bluetoothing (handy an strength of the signal) or radio bearing or arduino magic …

what do you thing?

the problem may be the changing light (thats why i thought about IR, but may be the theatre spots have IR-light in their spectrum to).

the stage width is about 20 meters.

thanks for your opinions!

n-b

Mmmh, there are a lot of stage projects last weeks. Search the vvvvorum for similar posts, might give you hints.

I wouldnt recommend IR in this case, because you already pointed at the problem of IR-light in stage beams. And they are more intensive than LEDs for sure.
For tracking more than one person video-tracking is quite advanced.
If you have budget I would recommend a radio tracking system (link somewhere in former posts). If not you need good experience in building it yourself.

But finding a solution its best you describe your project and tracking-aims (what data you wanna get) more detailed.

hi frank,

thanks for your response.
i was searching the forum a lot about the bluetooth solution, but could not find something similar (aside from the WiiRemote). because i thought the solution would be the cheapest.

at the moment the situation on stage is not clear (like the whole thing). thats why i could not describe the project.

Hi nicolas,

no sorry, I meant there have been topics about tracking people on stage.
“Cheapest” means low budget right? So, best is to go for a video tracking then. You’ll have some limitations though, but depending on your goal, that might be not big issue.

hi frank,

i already did some tracking with vvvv, but this time it is a bit different, beacuse i need to track just special persons, while others will be on stage to.

does someone has some experience with bluetooth and measureing the distance to the reciever by the quality of the signal?

i did some experiments with wlan signal strength once. the problem with software based systems is that you will get updates something like every seconds. also metal on stage will weirdly influence the tracking.

there are professional systems based on triangulation and time-of-flight - these are expensive.

what about mounting a reflector or an active light source on the special person?

let them wear hats with fiducials on top…

but now seriously:
assuming:
IR camera view is: from audience to stage
Theater Lights mostly have somehow same direction.

i could imagine that some battery-powered IR-LEDs hidden e.g. in the actors makeup, hair, costume, or mounted at their glasses pointing towards the IRcam make enough contrast to the (only) reflected IR of the theatre lights.
theatre sound professionals have developed lots of similar techniques for use with lavalier microphones

well, if you have 5 kW DeSisti in use as “Spitzlicht” this will be not successful…
but:

  • who does this
  • if you really use 5 kW “Spitzlicht” you are kind of mad…

the German ProLighting lingo expression “Spitzlicht” means: light pointing from backtruss towards the back of the actors head. purpose is mostly to define a better contour of the actors from the background. in bad movies this is often blueish and 5 minutes later you see a large ventilator turning slowly with blue lights behind…

don’t find a translation though.
catweasel, sudokuelliot, digipic?

@kalle

at least in photography this effect is called backlight, though there might be a more specific term for the effect of accentuating the edge of people.

Yup Back light or Rim light if you like, but Spitzlicht it is now, thats ace!

@kalle

i’ve seen & tried a fiducial hat recently…
not so comfortable
:)

http://remu.fr/wordpress/

thanks for your statements and ideas.

i thought i could find a way without a camera, but now it seams to be the cheapes way. if i find an other i will post it here.

the time-of-flight thing sounds great!

sorry for stealing your time.