Luminosità a parte, servono LED "wide angle", cioè
grandangolari, per evitare che la webcam non li veda più non appena giri un po' la testa.
In quelle schede tecniche devi quindi valutare anche il parametro ANGOLAZIONE.
Per fortuna si riesce a "convertire" un LED a "stretto campo visivo" con una semplice limetta: in pratica devi limare la punta rotonda e farla diventare piatta.
Come te la cavi con l'inglese?
Da
FreeTrack Wiki:
Active points
An active point model uses visible or infrared LEDs (5 mm or larger) to represent the tracking points, powered by battery, transformer (plug pack) or USB. The electric circuit is very basic and can be made by someone with little or no experience with electronics.
Common LEDs, like those found in remote controls,
have a narrow, highly focused beam which is not suitable for optical motion tracking. They can be easily turned into wide angle LEDs by filing their lens tips down flat. Alternatively,
wide angle LEDs can be purchased from specialist electronics retailers, like the infrared Siemens/Osram SFH485P, with a half-angle of 40 degrees.
Da
FreeTrack forum:
Q: The LEDs fade away when I turn my head only a small amount.
A: The viewing angle of your LEDs is too small,
increase the viewing angle by filing the LED lens tips down flat, almost to the metal part and then make the final finish transparent matte (not too shiny, not too rough). Alternatively you can buy wide angle IR LEDs like SFH485P or equivalent (+/-40 degrees half angle). These LEDs are unlikely to be available from consumer electronics shops, instead try major distributors like Farnell and RS Components or through a specialist like LumiTronix.
Q: I can't find SFH485P LEDs or the shipping costs are more expensive than the LEDs themselves!
A: Just use standard, widely available infrared LEDs, their viewing angle is too narrow for head tracking but this is easily fixed by filing the lens tips down flat. This reduces their brightness due to a wider emission angle but they're still no less bright than commercially bought wide angle LEDs like SFH485P.
