Pin-Pressions/ Rotation Sensor

I'm trying to build a sensitive pinpression device: one that can see 3d digital images. The device would be able to read, record and organize the depth of each pin. I think the first problem to overcome is figuring out a cheap way to measure pin depth. I think it will be best to do this with rotation sensors. Does anyone know how to build or where to buy cheap rotation sensors?

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One possibility is using a laser with either a moving galvanometer mirror or a spinning multi-faceted mirror and bounce the beam off the pinheads then reading the reflection with a photodiode. But if you're going to extremes, why not just bounce the laser off the surface your recording with the pins in the first place? Just a thot
The complexity of a device to measure each individual pin with its own individual sensor would be extremely high. The cheapest, simplest, method would be to record the pin data individually with a digital depth gauge. Is there a particular reason why you are trying to construct a face from a pin impression rather than use some other method? Cheers, Pat. Pending
yes (author)  Patrick Pending10 years ago
Well, I'm actually interested in mapping the whole body: I'm interested in pin impressions specifically, because I think they formalize an essential? way of thinking about sight. This device would "see" through "touch". I think that's nice. Also, full disclosure, this is the beginning of a larger project that may make sense to pursue with light based 3d scanners: eventually I want to build clothing from "skinning" and cutting the resultant digital model with digital tools. Does this make sense?
The practicalities of making a homemade device with that density of electronic sensors would be somewhere between extremely daunting to nigh-on impossible. If you managed to get your sensor device built you would then face the extremely complex task of interfacing all those sensors and collecting and processing the data.

However, you can map a face with just 6 points (or even less*):

1 & 2) Assume head is an ovoid. Measure chin and left side width

3) Measure left eye center point

4) Measure tip of nose (you could skip this if you were modeling M.J.**)

5) Measure center of mouth

6) Measure left ear

Now reflect points for other side of face and you have a very rough (albeit symmetrical) starting point. This procedure can be refined by adding the required level of detail (e.g., nose width, cheek height, eye width, etc.). Most faces are put together the same way, it's just the proportions that vary. By measuring only the key points you would save a lot of data processing and complexity.

  • - One I mapped earlier >> ;-)
** - M.J.>> :)


Pat. Pending
yes (author)  Patrick Pending10 years ago
Also, is this the appropriate section of this site to post questions of this nature? Thnx
Yes, I think so (it will also appear in the All forum where most people will see it). It would have been less confusing if you had provided more detail of what you are trying to achieve, but I see you have rectified that now. Cheers, Pat. Pending
gmoon10 years ago
Several different types for sure.

All (mechanical) computer mice have two optical rotation sensors--could you mod one of those? They sure have cheap goin' for them...
zachninme gmoon10 years ago
I agree, those two would be the best bet.
Heres how they work:
You have the 2 sensors, when you rotate them, they'll go in this order.
(1 = on, 0 = off)
0  01  01  10  1
Or... in reverse:
0  00  11  11  0
You'll have to figure out which is which, but from there you're good.
Are you proposing one sensor for each pin? It's just that I count in excess of 4000 pins on the one in the photograph! Maybe the Topic poster could suggest how many points are required to map the face. Cheers, Pat. Pending
yes (author)  Patrick Pending10 years ago
Yes, proposing one sensor per pin. The resolution doesn't have to be fantastic. Somewhere on the order of 1000 pins. Give or take half?
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