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RSS >  3-point system versus 4-point..., Advantages?
TURBOPossum #1 18/11/2007 - 18h06

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Hey guys, I was all set to go out and buy TrackIR, and BAM, I found this. What a splendid way of saving money. :D

Anyway, I've been using it for 2 days with the 1 point, 2dof system, and Today's project is to make a 6dof... My question is, is there any advantages to the 4-point cap over the 3-point cap?
Mdds #2 18/11/2007 - 19h02

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They both do the same trick. The 4 point cap is older and with FreeTrack 2.1, obsolete version
thosh #3 28/11/2007 - 16h15

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Hi,

i was starting to build the 4 point system then i found this post.

The 4 point cap is older and with FreeTrack 2.1, obsolete version


in the french manual feetrack v2.1 there is still shown how to build the 4point system. i dont understand french so i am not sure, what to do. Can someone help me, please?
i also dont find any documentation about the dimensions off the 3point system.

thx - thosh
tristan68 #4 29/11/2007 - 09h41

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Hello TurboPossum, Mdds, Thosh


I confirm :

- 4 points cap is obsolete design don't use it anymore
- 4 points cap is replaced by 3 points cap since 2.1, which has same performance specs.


Manual will be modified to reflect this.

cya.
Edited by tristan68 on 29/11/2007 at 09h41.
Mayo #5 24/01/2008 - 19h38

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So this means I should change the one I'm building at the moment to a 3P cap version?

I've just seen something about NAN errors, and though I'd go with the 4P cap?
spaceman #6 23/02/2008 - 02h29

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HI ..

I am new here and i am impressed of the possibility from Free Track - good work! :)

At first i tested with just one led to get a feeling how it is in game. After that i wanted more! :) Not least because of the limitation from 1point led.

So I just started to build a 4point prototype to see how it works. Still that time all system works with standard red leds and it works realy greate (with dark background)! Much better then 1point! Either when you just use 2dot.

But right know i begin to build my new 3potclip with IR and did allready mod my Webcam (remove IR-Filter). I prefer the 3portclip because of the usabililty and compact size (see guide with bycicle backlight). In aditional i want to build my new 3pointcap - you never know! - after i read in different places that 4pointcap is obsolete. Before i start to build my 3pointcap i tried out how good the 3pointcap works by turn of the 4th led in the middle from my prototype. First think i recognized that the yaw and pitch are much faster with the same settings. Ok .. no problem .. just turn down the Sensitivity .. i thouth. After that when i turn my head unwanted translations happens - like the Info-Text descripes. At all for me it looks like the movements are much more nervous with the 3pointcap than 4pointcap.

Maybe this is still setting stuff and u can help me out ...

...less leds more battery runtime! :)

PS: Sorry for my bad english .. i am german and tired! :)

Cu Spaceman
luca #7 02/03/2008 - 15h15

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Mdds @ 18/11/2007 - 20h02 a dit:

They both do the same trick. The 4 point cap is older and with FreeTrack 2.1, obsolete version



Maybe 4 point cap is obsolete, but even after a lot of adjustments  is 3 times better than 3 points clip for responsiveness and stability!  :(
Stay FREE
spaceman #8 02/03/2008 - 23h22

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I agree with u luca.

I tried the 3point cap by disable the fourth led from my protocap. After some test, i decided invest in the 4 point cap. I didn't care about the more work and more power supply because auf the 4th led. My new 4point cap works right know very well with just 60mA. With the 2AA battery (2000mA) i've got a running time about 30 houres. That's enough for me. :)

But how ever .. i am  spread out for the new version 2.2 and can't wait! :)

You can find pics from my cap and clip: http://forum.free-track.net/index.php?showtopic=466

Cu Spaceman
luca #9 03/03/2008 - 00h22

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Even if the 3led cap is a little bit better than 3led clip.
Btw, if you want to share any kind of knowledge about the improvement over the clip, I'm here.
:)
Stay FREE
Kestrel #10 03/03/2008 - 01h24

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spaceman @ 03/03/2008 - 00h22 a dit:


I tried the 3point cap by disable the fourth led from my protocap.



Disabling the middle led in the 4 point cap model (with dimensions as per the handbook) is NOT how you make a good 3 point cap model. The point plane is too close to being parallel with the camera plane which will cause numerous problems. It needs to be made deeper and lower.

It should be noted that the 4 point cap dimensions in FT 2.1 are broken, you can enter anything and it won't affect the true internal dimensions.
Newo #11 03/03/2008 - 06h26

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Kestrel @ 03/03/2008 - 02h24 a dit:

spaceman @ 03/03/2008 - 00h22 a dit:


I tried the 3point cap by disable the fourth led from my protocap.



Disabling the middle led in the 4 point cap model (with dimensions as per the handbook) is NOT how you make a good 3 point cap model. The point plane is too close to being parallel with the camera plane which will cause numerous problems. It needs to be made deeper and lower.

It should be noted that the 4 point cap dimensions in FT 2.1 are broken, you can enter anything and it won't affect the true internal dimensions.



Alright,  now unless I'm missing something here (which I may be due to the fact that I only speak english and the most up to date manual is in french, and the 3 point cap isn't in the english manual).
http://forum.free-track.net/index.php?act=wm&editmessage=4892&intopic=364
FreeTrack Forum - Support : Tracking System - Create new topic
Taking out the front center LED should theoretically make the 4 point cap into a 3 point cap.  The difference between doing that, and constructing a 3 point cap "correctly" is minimal.  The shape of the 3 points is for the most part, the same.  Just slightly different sizes.  A square is still a square, even if it is smaller.  Likewise a rectangle is still a rectangle, (or oblong) Even if one is longer than the other.

The way I see it,

a 4 point cap has the top LED 60 back and 100 high (using the side LED's as reference here)  and the side LED's are only 70 across from the back LED.

a 3 point cap has the top LED 100 back and 80 high (using the side LED's as reference here) and the side LED's are only 70 across from the back LED.

-----------------------------------------------

In conclusion, the 3 point cap simply has the side LED's further forward and slightly higher.  So unless I'm missing something which is written in french somewhere, then they should essentially be the same design.

[Edit]

I should add that I don't quite understand which it is you are refering to as the "point plane"

[/Edit]

[2nd Edit]

If you are reading this right now, then please don't post a reply as I'm aware that I've messed up here and I'm fixing my errors.

[/Edit]

[3rd Edit]

I should really plan out something like this before I post it, so that I get it right the first time.  Though my point remains the same.

Everything should be correct now

[/Edit]
Edited by Newo on 03/03/2008 at 06h44.

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