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Limitations and Choices among projectors for SL

Problems, solutions and discussion about scanning with a video projector and stripe patterns.

Limitations and Choices among projectors for SL

Postby Kvirre » Thu Sep 02, 2010 10:09 am

Hi, I have tried to get a sence of the essentials, and the limitations for Structured Light Scanning.

As far as scanning with laser goes, I have done several tests with different lasers, and it's also well documented on the forums and the Wiki. Now I seek the advice from you who have used diffrent projectors in the same environment.

In the "Pros and cons Laser vs. structured light" topic it's mentioned that:
_______________________________________________________________________________________
Structured Light
+ Faster scanning process
+ all kind of digital cameras can be used, including high quality DSLR

- to scan objects in verry different sizes from small to XL you need different projectors
- scanning in daylight environment is not possible
- projector is quite expensive
_______________________________________________________________________________________

I seek advice on the choice of projectors for micro-scanning and mid size scanning (up to 50 cm).

NOW, to the actual questions :)

1) Are larger HI- (resolution / ANSI lumen) projectors always a better choice?
- Since there is the matter focus-range limitations
- What are the limits in terms of object size here?
(and what are they? Light intensity / resolution)

2) Micro / Pico are also used for microscans, is it due to focus range? or is it a question of price / mobility?
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Postby hal » Mon Sep 06, 2010 12:19 am

Hello,

Kvirre wrote:Are larger HI- (resolution / ANSI lumen) projectors always a better choice?

If you can set your camera/photocamera at low exposure values, yes, a power projector is better (because you can scan in different environmental light conditions and you can scan different objects with different sizes). But usually the High power projectors are big, expensive and the minimun focus range isn't so short, so you can't scan little object or do macro scans.

Kvirre wrote:What are the limits in terms of object size here? (and what are they? Light intensity / resolution)

Never tryed, but I think that under 10x10x10 cm, to scan with a powerfull projector is hard. But take my words only as hypothesis.

Kvirre wrote:Micro / Pico are also used for microscans, is it due to focus range? or is it a question of price / mobility?

Not only a question of projector size and mobility, but yes, a question of focusing, too. With my micro projector I have a good focused projection at a distance of +/- 10 cm. And at short distances the projector power is perfect.


Hope this helps,
Mattia
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Re: Limitations and Choices among projectors for SL

Postby MagWeb » Mon Sep 06, 2010 8:24 pm

Hi,

just an add to Hal's advice:

All pico projectors I know own optics with a narrow angle of projection. This means less distortion of the projection and a better fit to the less wide camera optics. Avoid home cinema projectors with a wide angle of projection (these are build to get a big projection on short distance). Often even narrow projection angles have to be made narrower using added "close-up-lenses" as they are used in macro photography.

ad: powerful projectors at short distances: Some projectors give the options to set it up for different lightning conditions. If this isn´t enough you might reduce projection brightness modifying the projected patterns themselves.
For scanning in small sizes: Remember that the cam has to be rather near to the projector's optics. So bigger projector housings do not allow to get the cam close enough to have a intersectionangle of 35°- 40° at these short distances.

ad: SL scanning in daylight: To my surprise I found it much easier to scan in normal indoor light conditions using a SL scanner. Think the current way of DAVID's SL is only some shine of the potential of this technic.

Till now, this projector I like the most for scanning:
http://www.enwo-intl.eu/produkte/enwo-hd-2g (sorry: German site)

Gunter
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Re: Limitations and Choices among projectors for SL

Postby Kvirre » Tue Sep 07, 2010 11:45 am

Thanks for the advice and answers, this is what I was after.
Finally I decided to buy a Samsung SP-H03 and I will hopefully get it today.
(http://www.expertreviews.co.uk/projecto ... -projector)

I will try to use the SL patterns as well as "moving line" scanning.
As before, alot of configurations to try out.

Will post the results as they come along.

Thanks again
//Martin
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Re: Limitations and Choices among projectors for SL

Postby maxem » Mon Sep 27, 2010 8:12 pm

I too have been looking at the Samsung SP-H03 and also the AAXA M1 Limited Micro Projector:
the M1 is 75 lumens 800x600res $299 US
http://www.aaxatech.com/products/m1_micro_projector.htm

What i also like about the pico projectors is the possibility of playing back video or images without a computer tethered to it, with my current setup i have made a short video of the SL patterns that plays from my computer out to projector.

I did not know of the Enwo projector is it native 1280x768 Pixeln ?
or is that the max res file you can play through it and it scales it down to something like 800x600?
I am wondering if I should wait till they make true HD resolution pico projectors

I can't find anyone who sells that Enwo projector to the States
Gunter do you own the Enwo HD2 ? what is the real pixel resolution?
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Re: Limitations and Choices among projectors for SL

Postby MagWeb » Mon Sep 27, 2010 9:19 pm

Hi,

The EnWo´s res is native 1280x768 ......Enwo is just a German distribution brand.... here's the manufactorer: http://www.digiscope.url.tw/yellowpage/ ... html#48176

hmm .. it' s a nice projector if it does its job .... currently I´m trying to contact my reseller (seems to be busy) ....

I´d wait for DAVID 3.0 to see whether you´ll need some movie storage on the device - The EnWo HD2 does not have this possibility

Gunter
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Re: Limitations and Choices among projectors for SL

Postby maxem » Mon Sep 27, 2010 10:16 pm

thanks for the info!

all these little things i read around here about the new possibilities of SL in David 3 is killing me, i want it already!
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