Dear DAVID Community,

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Planeless Scanning

Questions, problems, comments and tips regarding the 3d scanning process.

Re: Planeless Scanning

Postby Mike_A » Sat Dec 04, 2010 11:54 am

I am slowly getting the hang of this,
This is a scan I did today, the little dude is 110mm high.
I am using a black card in front of the model to help focus the laser, I find this helps a lot (my old eyes :)
Does anyone know if there is a way of setting the opening size of Davids windows ?
Ie. I hate having to open a window then re size it.
I am looking forward to my new Gearbox from Brian !
viewtopic.php?f=6&t=2435
Cheers,
Mike.
Attachments
dude.jpg
532nm 5mw 3V Green line laser
Stepper-11YPG302S-LW4-R100 with 100:1 gear ratio Gearbox
Mono Camera - DMK31AU03. 1024 x 768 / 30fps
Arduino UNO/EasyDriver V4
Acer K11 Projector.
www.mikeannear.com
Perth, Western Australia.
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Posts: 64
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Re: Planeless Scanning

Postby vw_bus » Sat Dec 04, 2010 5:46 pm

Thanks for the links to the Reigl site. The 'principle of operation' sections are very interesting. The Terestrial Scanner system is remarkably similar to David, but with the whole scanner mounted on a rotary axis, so the system has '360 degree vision'.
Does it use the laser to illuminate a plane, like David, catching a plane of data per frame, or just a beam to find a series points in 3D space, similar to the laser theodolites that Surveyors use? The SLR camera suggests is is capturing a plane per frame some how, even though the intersection angle between the camera view and the illuminated plane would be almost zero over a long range. From my limited understanding, it can't be working just like David because the near zero intersection angle would not allow accurate triangulation.
These long range systems must be using a seriously powerful laser? How do they avoid that being dangerous, as scanning such large scenes from a distance, you will almost certainly shine it into someone's eyes. Do they use visible, or infra red light? Sorry about all the questions!

I've been looking into using a front surface mirror mounted on my stepper motor so I don't have to rotate the actual laser. My goal is to have remote control of the laser focus, and camera focus and aperture using radio control servo's, as I wan't to build a robust planeless scanner that I can control entirely from the laptop. I have only just finished my planeless scan hardware though, and I have not yet got good results from it, so I have a lot more learning to do still!
vw_bus
 
Posts: 51
Joined: Sat Mar 20, 2010 7:36 pm
Location: UK

Re: Planeless Scanning

Postby milz » Sun Dec 05, 2010 7:47 am

hi

Mike_A wrote:Does anyone know if there is a way of setting the opening size of Davids windows ?


Advanced settings > Window3D

your wooden men looks fat think he need a dietary :D
or did i own the anorexia version :lol:
http://webin3d.de/gallery.php?show=wmen

mfg milz
Xeon x5650@4ghz
Cam : USB2 CCD 1024x768 / USB3 1280x900
Laser : LC532-5-3-F(16x65) Focusable Green
Projector Acer X110P / Acer K132
dControl one David control box + Turntable + automatic texture lights
mooooom bathroom!!!!!!
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Location: Germany Cologne

Re: Planeless Scanning

Postby Mike_A » Sun Dec 05, 2010 8:30 am

Hey Hi,
Thanks Milz, yes, I have the "Fat Aussie" version of the wooden man :)

Hi VW_Bus,
The Riegl scanners work by either "Time of Flight" or "Phase Shift" (or a combination of both)
The Time of Flight scanners fire out a pulse of laser light , then time how long it takes to come back. They do this thousands of times per second.
They can shoot over 2km.
The Phase Shift scanners fire out a beam at a certain Frequency, then measure the frequency change in the return beam.
They don't calculate "Planes" as such, the SLR camera is for creating a coloured pointcloud, similar to Davids "Texture Grab"
Yes, they are seriously powerful !. But, if you imagine they have a mirror spinning on a horizontal axis to make a vertical "Fan" of laser beams, then the whole "scan head" spins on a vertical axis, its actually quite hard to look into the instrument. They also use a Class 3R laser which is relatively safe.
http://en.wikipedia.org/wiki/Laser_safety

Some Scanners use a front silvered mirror for rotating their beam, Its OK for use in clean environments, but they are terrible in industrial situations with dust and condensation on the mirror (from personal experience :)

I hope that helps :)
Cheers,
Mike.
Attachments
puppet2.jpg
532nm 5mw 3V Green line laser
Stepper-11YPG302S-LW4-R100 with 100:1 gear ratio Gearbox
Mono Camera - DMK31AU03. 1024 x 768 / 30fps
Arduino UNO/EasyDriver V4
Acer K11 Projector.
www.mikeannear.com
Perth, Western Australia.
User avatar
Mike_A
 
Posts: 64
Joined: Fri Sep 10, 2010 2:07 am

Re: Planeless Scanning

Postby vw_bus » Mon Dec 06, 2010 2:10 am

Hello Mike,
Thanks for the extra info. It sounds like the long range scanners are effectively very fast, automated versions of the laser theodolites used by surveyors. I imagine they don't need calibrating to suit each scan at all then. A bit like radar or sonar, but with light?
vw_bus
 
Posts: 51
Joined: Sat Mar 20, 2010 7:36 pm
Location: UK

Re: Planeless Scanning

Postby Mike_A » Sun Dec 12, 2010 2:38 am

Hi vw_bus,
Yep, thats right. They don't need any calibration per scan.
They are laser theodolites on "Steroids". Actually, some of the new Total Stations (theodolites) also have a scanning function, but a lot lower scan rate than dedicated scanners.
Cheers,
Mike.
532nm 5mw 3V Green line laser
Stepper-11YPG302S-LW4-R100 with 100:1 gear ratio Gearbox
Mono Camera - DMK31AU03. 1024 x 768 / 30fps
Arduino UNO/EasyDriver V4
Acer K11 Projector.
www.mikeannear.com
Perth, Western Australia.
User avatar
Mike_A
 
Posts: 64
Joined: Fri Sep 10, 2010 2:07 am

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