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Scanning Tall Objects

The place for all topics related to the 'Shapefusion' tool of DAVID.

Scanning Tall Objects

Postby dsp5500 » Thu Jan 15, 2015 11:51 am

Is it possible to scan a tall object in say 4 sections and have fusion join into one object?

Rob
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Re: Scanning Tall Objects

Postby JDM Dyno » Thu Jan 15, 2015 3:28 pm

yes its possible but you may need to put some sort of reference marks or objects so you can align them if there isn't much detail, small bits of modelling clay or blue tack or play-doh etc can help wit alignment
Camera's: 2 x DFK 42BUC03 Duel Camera,
c615 modified with Computar megapixel lens
lenses: 2 x Pentax 12mm, 2 x Computar 8mm
Optoma ML300 Projector
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Re: Scanning Tall Objects

Postby micr0 » Thu Jan 15, 2015 8:36 pm

I use a hot glue gun and ping pong balls or marbles. Having smooth consistent spheres I find to be very helpful in alignment. Try to place them so that you can see at least two of them in one scan.

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Re: Scanning Tall Objects

Postby dsp5500 » Fri Jan 16, 2015 7:12 am

Ok sounds good, Im talking about something in the 2feet tall range and under. Replace the balls with dot stickers?
So would you calibrate and setup for the bottom 3rd and scan. then would you recalibrate for the middle third, adjust projector and camera then scan and again fro the top third?
And fusion would bring all the scans together?

Rob
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Re: Scanning Tall Objects

Postby NARMELLA » Fri Jan 16, 2015 9:30 am

Hi Rob,

Using Dot stickers is a great idea ,unfortunately not in scanning by using david laser scanner.
David is using the geometry of each scan to align it , it does not recognize dot stickers and they are not big enough to use them as a geometry in alignment :(

You have to guess that where you will get bad alignment using shape fusion.
And As JDM Dyno and micr0 wrote above You have to add some geometrical shapes (specially Spheres) around or on the part.
In total by adding these spheres , You are changing the geometry of the part to have a nice alignment .
This strategy gives us enough ability to scan large objects easily .
Only add extra geometries on the part , calibrate your scanner and scan the part.

Notice that :
By having a bit error in calibration process you will get more deviation in scanning large objects :wink:

GOOD LUCK
Data projector : NEC VE 281
Camera(s) : Canon eos 600D (3x)
Software : Lets scan 2.5 + David laser scanner 3.9
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Re: Scanning Tall Objects

Postby dsp5500 » Fri Jan 16, 2015 2:15 pm

So a two foot tall statue is it better the scan in sections or all at once?
If attaching balls on something that size would painted 4mm ballbearings be the go?

Thanks for the reply,

Rob

Oh Narmella funny you should reply as i was just reading you Lets Scan thread!
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Re: Scanning Tall Objects

Postby JDM Dyno » Fri Jan 16, 2015 4:13 pm

if you have a larger calibration panel you can do it in one, you would have less resolution than splitting into 3 sections but easer to align done in one view,

as Narmella said most important to have a good accurate calibration corner

ball bearing painted white is good yes but if your statue has lots of detail you may not need anything

2014-12-31_17-14-48.jpg

I did these two separately on turntable 16 scans plus top scan and only needed free alignment to get very good results as they have enough details for David to work with
if you did the full statue then repeated in 3 sections for more detail and aligned to full scan for good alignment then removed full low res scan you should get good detail and good alignment but would take more time, but you wouldn't have to remove the balls and rescan to fix the holes left by them,

I would say try with turntable set to 22.5° you get a good overlap of the scans and I've found it easy to align lots of low detail things this way without use of balls etc but its easy to add some if you have a hard time with an object

p.s on a 2 foot tall object I would use some bigger balls than 4 mm some 12mm balls round the base and in low detail arias is probably best,
Camera's: 2 x DFK 42BUC03 Duel Camera,
c615 modified with Computar megapixel lens
lenses: 2 x Pentax 12mm, 2 x Computar 8mm
Optoma ML300 Projector
Turntable

www.jdm-dyno.co.uk
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Re: Scanning Tall Objects

Postby dsp5500 » Sat Jan 17, 2015 4:57 am

So theres no problem aligning the scans if your moving the camera/projector for each section. Is it just a matter of re calibrating after moving up for each section?
Or maybe a better option is to lay it horizontally and just slide it across in thirds?
It would need to be done in thirds I think to pick up all the detail.
JDM Dyno Ive seen your threads and your scans are tight!

Rob
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Re: Scanning Tall Objects

Postby JDM Dyno » Sat Jan 17, 2015 11:33 pm

If you have your setup on one fixture like the sls 2 or this one of mine or similar
DSC_0272[1].jpg


then you can just wind up the tripod to the next level without re-calibrating, as long as you don,t move the camera or projector in relation to each other or there focus you can move it to any position, I would probably do 360° at each of the 3 level's, align each level, group them, then align the groups to each other, with a good mount of overlap it should work well
Camera's: 2 x DFK 42BUC03 Duel Camera,
c615 modified with Computar megapixel lens
lenses: 2 x Pentax 12mm, 2 x Computar 8mm
Optoma ML300 Projector
Turntable

www.jdm-dyno.co.uk
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Re: Scanning Tall Objects

Postby WP2016 » Tue Jun 21, 2016 6:54 pm

Hello, I see you are other users posting dual camera setup. I am wondering if David supports such setup because the video source provides only one camera. Thanks!
Projector: Acer K132 + 1/2/4/10 X closeup dai. 52 mm.
Camera: Grasshopper 3 GS3-U3-28S4C-C (@ 1600 X 1200, 30 fps); Lens: 8-50 mm F/1.4.
Computer: USB 3.0, CPU: 2.6-3.5 GHz, GPU: 3G NVidia 970M, 32G RAM.
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