Lighting the scanned object (Page 1 of 2)

I bought a meter of Dotstar LED strip from Adafruit.  It's not ideal since the best I can do is make white-ish light by turning on all three RGB LEDs at once; I really wanted to get the Dotstar white LEDs but they were out of stock on the breakout boards and I didn't feel up to making my own. So I'll at least get started with a couple pieces of the strip, and can always convert later.

I have a couple of breakout boards with 74AHCT125 chips on them; I'll need to rewire because they were designed for NeoPixel strips, but it should be straightforward to use them with Dotstars. The 12 volt bus on my power supply should have more than enough capacity to drive a few LEDs too.

I'm building my own HAT board for the Pi 2 to hold the stepper driver, ULN2003A for the lasers and a voltage regulator, and the most challenging thing will be finding real estate on the board to add the 74AHCT125...

I was wondering about the possibility of including a light sensor, either mounted on the camera tower and pointing at the object or mounted just under the edge of the turntable, so I could try to keep the light level constant. I've already had one scan that turned out very strange-looking because the sun was setting behind a tree and the light level in the room kept changing!

I was thinking of adding LEDs around the top near the edge the rotating base so I can ensure I have more consistent lighting.  My hope is that I can drive these from the Pi.

Sounds like a nice addition - are you using two more of the pins on the ULN2003A?

FWIW,  I just set my Atlas 3D.   I had lighting issues as well.    I put the scanner inside one of those popup 18" light boxes that they sell for people to use to make decent ebay photos.  So it turns all the direct lights in my workspace into ambient light.    It works pretty well so far.   I'm scanning TINY objects, so it's all calibration issues for me.

being lasers are used to illuminate object for camera, I would think any other stray light is just likely to cause ill effects/reflections and a darkroom type enclosure would be a better idea plus blocking any other light even from LEDs from interfering with scan. I am planning to do just that with mine. we are not taking color photos after all. just a 3D contrast image with sharp edges for detail.

Uriah,

I'm presuming there are holes on the Atlas board where I can solder a 4x1 0.1" header to access the pins you were talking about (to control 5V/500ma devices from the PI through the Atlas board).  I'm not sure which holes those would be or which pins are which?  How they would relate to PI GPIO pins, for example.  Which pins are data/ground/power?

Where should I solder the header?

I haven't been able to find a schematic or layout of the board (maybe I'm not looking in the right places).  For what it's worth I was a kickstarter June full kit supporter.

If these things are obvious, then I'm sorry that I haven't been able to figure this out myself....

Thanks for any help,

Byrom

Byrom,

If you've found an Eagle file then it's not the design used in ATLAS 3D.  The picture below shows the ATLAS 3D PCB with the expansion ports.  The pins are outputted from the ULN2003A so some voltage is dropped resulting in 4.5V.  When the ribbon cable is hooked up to an ATLAS 3D, the two outputs can be triggered via the RPi pins.  I don't recall which but can look it up later.

- Uriah

Just for anyone who's curious:

I got native lighting to work with the expansion port for power and hardware SPI to set colors/brightness.  I should clarify that the expansion port is hardware pins 13 and 15, GPIO2 and GPIO3 (WiringPI), BCMGPIO 21or27 and 22.  So you can control it like this:

gpio mode 3 out
gpio write 3 1        (to enable 4.5v)

I soldered wires onto the bottom of the board at PI pins 23 and 19 for the SPI clock and data out.  Put those through a 74AHCT125 (as suggested by Adafruit docs for DotStar LEDs) and eveything works now, all self-contained in the Atlas 3d.

Um, I'm not sure how to answer that.  I don't think it's doing what you think it's doing.  Do you have yours working yet?

The lasers are just projecting a line onto the object and the shape of the line from the camera image tells the scanner where to "place" the (color) pixels of the object image in 3D.  So, yeah, it is a color scan. 

It's easy to find scanned color models in the example pictures on this board.  In my opinion, Pirvan's write ups here on getting a good scan and post processing are very good, so look for those when you do get started.

also you want to dull anything around the laser so reflections are not created when laser light hits it especially parts of scanner which are not even being scanned some times object being scanned can also reflect stray laser light so dull coat may be used if model is able to to be painted or dulled down reflective surfaces. you will see this mentioned in several 3D scanning videos/tutorials.

The ATLAS 3D scanner can combine the laser data and the camera color data to produce full color 3D reconstructions.

Hence, lighting the object appropriately is important in order to capture full color, 3D scans like this: