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Optoma pk201

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

Optoma pk201

Postby andyjk » Sat Mar 17, 2012 11:52 am

I have an optoma pk201 projector to scan objects around 8cm wide. I use this as it will focus on a screen of this width without additional lenses.

I have noticed I have to run it at a max brightness of only 120 out of 255 because the difference in brightness from 120 to 255 is very small. I have also read on the forum that the (similar) pk301 has poor gamma and some colour blurring.

My results are OK, but I use my own patterns/software - I use 2 sets of 3 sine waves. In each set the three waves are 120 degrees apart. The 2 sets are 60 degrees shifted and from these 2 sets I calculate an average (this compensates for gamma). I then uses Gray codes to identify each sine wave cycle.

I was going to try David but have 2 questions :

1) What patterns does David generate ? I don't understand when people talk about 'frequencies' and 'shifts' on this forum. Is the frequency basically how many sine waves across the pattern (eg eight) and the shift how many patterns displayed (eg three at 120 degrees apart, or 4 at 90 degrees apart etc). Then the Gray codes are presumably sent afterwards. Also can David send multiple sets of sine wave patterns (as I do) to compensate for gamma errors ?

I attach an example of a dental stone model (upper left quadrant) in point cloud form

2) I was going to upgrade my projector as it has poor reviews here. I'm not sure if its the resolution (858x600) or the poor characteristics (eg only being able to use from 0 to 120 intensity for pattern generation) or the focus range that affects the quality of my scans. If I want to zoom in and scan something say 3x3cm, are you guys fitting lenses which focus the display to this width ? Some of the coins/models are impressive on here, I didn't know what volume you are focusing your projectors down to.

I am thinking of trying the Acer K11 but its resolution is only the same as my projector - perhaps it will be no better, or perhaps you are focussing it down to a 30mm FOV for scanning coins etc ? Also are you generally able to use the full 0 to 255 intensity range ? (NB My problem is NOT due to my camera 'maxing out' - it is my projector).

Thanks

Andy
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