Category: Photography & Images

Taking & making images.

Home Ec, Machine Shop, Photography & Images, Science, Software

Medium Ricotta Lid Box: QR Code vs. Chipboard

Another box from the festi.info box configurator to collect more lids in a kitchen drawer:

Medium Ricotta Lids box
Medium Ricotta Lids box

This was really a thinly veiled excuse for a deeper look at the QR code generator encoding the myriad parameters required to create the box and see what happens when you try to burn such a complex thing into chipboard.

Spoiler: chipboard has very low contrast and really does not work well with high-density QR codes.

Although the festi.info box generator can produce QR codes, I used qrencode (available in your Linux distro) on the command line to generate QR code image files with specific settings:

qrencode --level=M --size=6 --dpi=254 --output='Ricotta Lids 2 lb - chipboard.png' 'http://festi.info/boxes.py/ABox?FingerJoint_angle=90.0&FingerJoint_style=rectangular&FingerJoint_surroundingspaces=2.0&FingerJoint_bottom_lip=0.0&FingerJoint_edge_width=2.0&FingerJoint_extra_length=0.0&FingerJoint_finger=2.0&FingerJoint_play=0.0&FingerJoint_space=3.0&FingerJoint_width=1.0&x=200.0&y=120.0&h=60.0&outside=0&bottom_edge=h&thickness=1.4&format=lbrn2&tabs=0.0&qr_code=0&debug=0&labels=0&reference=0&inner_corners=corner&burn=0.04&language=en&render=0'

The key parameters:

  • --level → error correction level
  • --size → size of the smallest square (“module”) in pixels
  • --dpi → DPI of the output image file

The default file type is PNG. The unusual 254 DPI makes each pixel exactly 0.1 mm wide and a peculiar 169.33 DPI = 0.15 mm came in handy for the first pattern.

The final parameter is the character string to encode, which you should definitely quote to prevent the shell from wrecking things while trying to help you.

A pattern with 4×4 pixel modules didn’t scan at all:

Chipboard QR code - 15pct 0.15mm 4x4 - overview
Chipboard QR code – 15pct 0.15mm 4×4 – overview

A closer look shows the modules have ragged edges due to laser timing variations during the engraving scans and gaps between successive scans because the spot size is less than the 0.15 mm scan interval:

Chipboard QR code - 15pct 0.15mm 4x4 - detail
Chipboard QR code – 15pct 0.15mm 4×4 – detail

Increasing the module to 6×6 pixels at a 0.1 mm scan interval :

Chipboard QR code - 15pct 0.10mm 6x6 - overview
Chipboard QR code – 15pct 0.10mm 6×6 – overview

A closer look shows the larger module reduces the relative size of the timing errors, while the decreased line spacing tidies up the blocks:

Chipboard QR code - 15pct 0.10mm 6x6 - detail
Chipboard QR code – 15pct 0.10mm 6×6 – detail

Reducing the power from 15% to 10% reduced the contrast to the point of illegibility:

Chipboard QR code - 10pct 0.10mm 6x6 - overview
Chipboard QR code – 10pct 0.10mm 6×6 – overview

A closer look shows the engraving barely punches through the surface and has somewhat more ragged edges due to the tube’s pulsating startup current at very low power:

Chipboard QR code - 10pct 0.10mm 6x6 - detail
Chipboard QR code – 10pct 0.10mm 6×6 – detail

I also tried 5×5 modules with similar results.

The laser spot size sets the engraving scan interval, which then determines the DPI value for the QR code image. With all that matched up, you can send the images directly to the laser in Passthrough mode, without having LightBurn resample the pixels and change the module’s shape.

Looked at from a different angle: given the laser spot size and the module size, the QR code image size is not under your control.

From another angle: given a QR code image size in, say, millimeters, and the engraving scan interval, the module size is not under your control.

All this is moot if you print QR codes on a high-resolution / high-contrast printer. It’s just the gritty nature of laser cuttery that limits what you can accomplish.

And, of course, using a material less awful than chipboard will definitely improve the results.

If you want a similar box of your own, here ya go:

Medium Ricotta Lids - chipboard QR code - default
Medium Ricotta Lids – chipboard QR code – default

The URL is too ugly to print, but you can copy it from this link.

Aphorisms, Photography & Images, Recumbent Bicycling, Science

Stone Cold Swerve

We’re southbound on Rt 376, ticking along at about 15 mph, with fresh string-trimmer debris littering the shoulder:

T – 50 ms

Did you notice the rock? I didn’t.

The fairing ripples as my front tire hits the left side of the rock:

T = 0

I have no memory of the next two seconds.

The offset impact turns the front wheel to the left, so the bike steers out from underneath my weight:

T + 500 ms

Because the bike frame was still aimed straight ahead, the wheel is steering further to the left and putting me even more off-balance. I am somehow trying to lean left far enough to get my weight lined up with the bike:

T + 1.0 s

One second into the event, Mary has no idea what’s going on behind her.

My memory resumes with an image of the yellow midline just beyond my left foot:

T + 2.0 s

Mary heard an odd sound and asks (over the radio) “Are you all right?”

I’m approximately balanced, turning toward the shoulder, and manage to shout “NO!”:

T + 3.0 s

I’m coasting toward the shoulder with my feet off the pedals:

T + 4.0 s

Mary is stopping and I coast past her:

T + 5.0s

Landing gear out:

T + 6.0 s

Back on the shoulder, lining up with the guide rail:

T + 7 s

Dead slow:

T + 8.0 s

Docking adapter deployed:

T + 9.0 s

And stopped:

T + 10.0 s

I sat in that exact position for nearly four minutes.

A slideshow view of the same images so you can watch it unfold:

  • T – 50 ms
  • T = 0
  • T + 50 ms
  • T + 500 ms
  • T + 1.0 S
  • T + 2.0 s
  • T + 3.0 s
  • T + 4.0 s
  • T + 5.0 s
  • T + 6.0 s
  • T + 7.0 s
  • T + 8.0 s
  • T + 9.0 s
  • T + 10.0 s

Doesn’t look like much, does it?

If I could have looked over my shoulder, this is what I would have seen, starting at T = 0 with the rock impact blurring the image:

  • T = 0
  • T + 67 ms
  • T + 1.0 s
  • T + 2.0 s
  • T + 3.0 s
  • T + 4.0 s
  • T + 5.0 s
  • T + 6.0 s
  • T + 7.0 s
  • T + 8.0 s
  • T + 9.0 s

Surely scared the daylights out of that driver, perhaps confirming all the usual expectations of crazy bicyclist behavior.

Here’s what Mary would have seen over her shoulder, again starting at T = 0 with the fairing bulging from the impact:

  • T = 0
  • T + 467 ms
  • T + 833 ms
  • T + 1.0 s
  • T + 2.0 s
  • T + 3.0 s
  • T + 4.0 s
  • T + 5.0 s
  • T + 6.0 s
  • T + 7.0 s

Timing is everything.

That Benz is new enough to have automatic emergency braking, as it slowed pretty dramatically while I was busy getting out of the way, but it’s not clear whether AEB knows about small / lightweight targets like pedestrians and bicyclists.

We completed the ride as planned, although I finally realized the front fender bracket had broken a few miles later.

Every adult human male has at least one story beginning “But for that millisecond or inch, I wouldn’t be here.” Now I have one more.

I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.

Frank Herbert, Dune
Electronics Workbench, Photography & Images, Recumbent Bicycling

Newmowa NP-BX1: Video Duration vs Charge

Having run the Newmowa NP-BX1 batteries through my old Sony HDR-AS30V helmet camera a few times, a plot seemed in order:

Newmowa NP-BX1 video duration vs charge
Newmowa NP-BX1 video duration vs charge

The cluster of dots shows most of our rides last about an hour.

The line is an eyeballometrical fit, slightly coerced to pass through the origin because that’s where it should go.

The 9.1 mA·hr/min slope is in reasonable agreement with past results, given different batteries and charger. The Keweisi meter emerged first from the box.

Straining the hr/min dimensional nonsense out of the slope suggests the camera averages 550 mA and 1.9 W. Derating those by a few percent to account for the recharge efficiency might be in order, but they’re surely in the right ballpark.

Home Ec, Machine Shop, Oddities, Photography & Images

High Impact Art(ifact)

At first we thought a mighty crunch in the morning meant the trash collection truck had dropped a garbage bin from a great height, but the sound of sirens and a myriad flashing lights revealed the true cause in our neighbor’s front yard:

NHR Crash - frontal view
NHR Crash – frontal view

The extent of the damage was more apparent from the road side:

NHR Crash - passenger side
NHR Crash – passenger side

Another one that ain’t gonna buff right out.

The driver was walking around uninjured and the ambulance left quietly.

A day later, the trajectory became apparent:

NHR Crash - trajectory
NHR Crash – trajectory

The right side barely kissed the tree on the right, but the front wheel hooked the utility pole (that’s the new pole in the picture), snapped it off at ground level in addition to the usual break maybe ten feet up, and bounced a piece off the other tree:

NHR Crash - utility pole
NHR Crash – utility pole

I didn’t know you could shatter a cast aluminum alloy wheel, but the missing half of the outer face was lying amid the rather scrambled stone wall along driveway.

We’re reasonably sure we know the cause. Feel free to draw your own conclusions.

After the flatbed hauled away the car and everybody left, I harvested a few pounds of interesting debris from the lawn:

NHR Crash - tempered glass
NHR Crash – tempered glass

It’s tempered glass from the driver-side windows, shattered into small chunks and barely hanging together in those sheets. Laminated windshield glass is entirely different stuff.

The smaller chunks glitter like jewels:

NHR Crash - tempered glass fragments
NHR Crash – tempered glass fragments

Obviously, the window had a bit of tint.

The smallest chunk, seen from its flat surface, shows the cuboid fragments:

NHR Crash - tempered glass fragment - front
NHR Crash – tempered glass fragment – front

A side view shows more complexity:

NHR Crash - tempered glass fragment - side
NHR Crash – tempered glass fragment – side

Tempering prevents a glass sheet from shattering into long knife-blade shards. Although the edges of the fragments are not keen, we are dealing with broken glass: they are sharp.

How sharp? They make glass knives for slicing eyes and cells.

Broken tempered glass also sheds razor-edged flakes perfectly shaped to penetrate bike tires, although most roadside glass comes from ordinary beverage bottles. The tiniest flakes can make a mess of your eyes, so exercise at least some rudimentary shop safety practices.

Those slabs ought to be good for something, even if they fall apart at the slightest touch …

Machine Shop, Oddities, Photography & Images

HP 09872-60066 Digitizing Sights

A long-delayed bench cleanup united these two HP 09872-60066 digitizing sights:

HP 09872-60066 Digitizing Sights
HP 09872-60066 Digitizing Sights

I’ve used the one on the right (above) with my HP 7475A plotters, but the other sight obviously won’t fit:

HP 09872-60066 Digitizing Sights - diameters
HP 09872-60066 Digitizing Sights – diameters

The metal-shell version is advertised as “09872-60066 Calibration Pen for fit HP DesignJet 2000CP 2500CP 2800CP 3000CP 3500CP 3800CP Original New” which makes absolutely no sense, as those were inkjet and laser printers with (AFAICT) no need for a “calibration pen”. Because nobody with those printers will buy (or even look for) a widget they can’t use, the price is surprisingly low, compared to the real ones occasionally found on eBay.

My guess: somebody halfway around the planet found a pile of Genuine HP plastic snap boxes, filled them with knockoff sights vaguely similar to the original (perhaps intended for a different plotter?), and marketed them with the usual (lack of) attention to veracity.

Anyhow, we find our contestants standing in the light on a micropositioner under the microscope:

HP 09872-60066 Digitizing Sights - test setup
HP 09872-60066 Digitizing Sights – test setup

The old sight (genuine HP plotter) has a clean field of view:

HP 09872-60066 Digitizing Sights - old full
HP 09872-60066 Digitizing Sights – old full

With a tidy dot in the middle:

HP 09872-60066 Digitizing Sights - old detail
HP 09872-60066 Digitizing Sights – old detail

The new (to me, anyhow) sight has rather coarse hexagonal light pipes with a gaps at the edges:

HP 09872-60066 Digitizing Sights - new full
HP 09872-60066 Digitizing Sights – new full

The spot at the middle is raggedly machined / drilled, with a bottom sufficiently un-flat to prevent focusing on the whole thing at once:

HP 09872-60066 Digitizing Sights - new detail
HP 09872-60066 Digitizing Sights – new detail

I have a vague project in mind to turn the new (craptastic) sight into an optical alignment punch, but the spot seems a bit too large for that.

Photography & Images, Recumbent Bicycling

Sharing the Road on Raymond Avenue: Zero Clearance

We’re bicycling on Collegeview Avenue, approaching the eastern traffic circle (of three) along Raymond Avenue. I’m in the lead, hauling a trailer with the week’s groceries:

Zero Clearance - Ed Front - 2021-09-07 - 0497
Zero Clearance – Ed Front – 2021-09-07 – 0497

The four digit frame numbers tick along at 60 fps for my helmet camera and 30 fps for the rear cameras.

Note the “splitter” (a.k.a. “pedestrian refuge”) on the left, intended to separate Collegeview’s incoming and outgoing traffic. It formerly had one non-reflective black bollard on each side of the ladder crosswalk, but errant drivers destroyed so many bollards along Raymond that they’re now WONTFIX remnants. The flush concrete disk in the lower left of this picture will become relevant in a few seconds of real time:

Zero Clearance - Ed Front - 2021-09-07 - 0593
Zero Clearance – Ed Front – 2021-09-07 – 0593

Collegeview has the same deteriorating pavement as found along Raymond Avenue, so we must maneuver beside the potholes:

Zero Clearance - Mary - 2021-09-07 - 0797
Zero Clearance – Mary – 2021-09-07 – 0797

The potholes make maintaining a safe-ish distance from the parked cars somewhat difficult:

Zero Clearance - Ed Rear - 2021-09-07 - 1140
Zero Clearance – Ed Rear – 2021-09-07 – 1140

All of us are slowing to stop at the traffic circle, with Mary behind the car that will eventually stop beside me:

Zero Clearance - Ed Rear - 2021-09-07 - 1522
Zero Clearance – Ed Rear – 2021-09-07 – 1522

Mary could see the car behind her in her helmet mirror, but she’s slowing to stall speed with no time for sightseeing and no room for maneuvering. The view from the camera on the seat frame behind her left shoulder:

Zero Clearance - Mary - 2021-09-07 - 0957
Zero Clearance – Mary – 2021-09-07 – 0957

Two seconds later:

Zero Clearance - Mary - 2021-09-07 - 1078
Zero Clearance – Mary – 2021-09-07 – 1078

One second:

Zero Clearance - Mary - 2021-09-07 - 1110
Zero Clearance – Mary – 2021-09-07 – 1110

Two more seconds:

Zero Clearance - Mary - 2021-09-07 - 1182
Zero Clearance – Mary – 2021-09-07 – 1182

Mary has stopped, as shown by the parked car’s unchanging position in the frame over on the left in the next images. The driver, however, continues creeping slowly forward; there can be no doubt she sees Mary at this distance.

After three more seconds:

Zero Clearance - Mary - 2021-09-07 - 1270
Zero Clearance – Mary – 2021-09-07 – 1270

One second later, the front wheel is exactly at Mary’s left foot:

Zero Clearance - Mary - 2021-09-07 - 1308
Zero Clearance – Mary – 2021-09-07 – 1308

The same events, viewed from the camera on my bike, start less than one second from the 1522 image above. I’m stopped, while the driver next to me continues to roll forward.

Mary is extending her left leg in preparation for a complete stop, at about the same time as the 1078 image:

Zero Clearance - Ed Rear - 2021-09-07 - 1542
Zero Clearance – Ed Rear – 2021-09-07 – 1542

Three seconds later her toe touches the pavement, while both she and the driver continue moving forward very slowly:

Zero Clearance - Ed Rear - 2021-09-07 - 1634
Zero Clearance – Ed Rear – 2021-09-07 – 1634

Five seconds later, she is stopped with her foot firmly planted:

Zero Clearance - Ed Rear - 2021-09-07 - 1773
Zero Clearance – Ed Rear – 2021-09-07 – 1773

And the driver continues moving:

Zero Clearance - Mary - 2021-09-07 - 1333
Zero Clearance – Mary – 2021-09-07 – 1333

Another five seconds and the sidewall bulge of the car’s radial tire is pressing her foot to the pavement:

Zero Clearance - Ed Rear - 2021-09-07 - 1934
Zero Clearance – Ed Rear – 2021-09-07 – 1934

A closer look:

Zero Clearance - Ed Rear - 2021-09-07 - 1946 detail
Zero Clearance – Ed Rear – 2021-09-07 – 1946 detail

She yanks her foot away:

Zero Clearance - Ed Rear - 2021-09-07 - 1953
Zero Clearance – Ed Rear – 2021-09-07 – 1953

While the driver continues to creep forward:

Zero Clearance - Mary - 2021-09-07 - 1397
Zero Clearance – Mary – 2021-09-07 – 1397

Sometimes, it’s the only way to get some attention:

Zero Clearance - Ed Rear - 2021-09-07 - 2026
Zero Clearance – Ed Rear – 2021-09-07 – 2026

Mary is now off-balance, leaning on the car door, explaining what just happened:

Zero Clearance - Ed Rear - 2021-09-07 - 2152
Zero Clearance – Ed Rear – 2021-09-07 – 2152

Mary regains her balance as the driver backs cautiously away:

Zero Clearance - Mary - 2021-09-07 - 1546
Zero Clearance – Mary – 2021-09-07 – 1546

Were the bollard still atop that sad concrete foundation, the driver might not have driven up on the splitter to get around Mary, if only to avoid scuffing a fender:

Zero Clearance - Ed Rear - 2021-09-07 - 2479
Zero Clearance – Ed Rear – 2021-09-07 – 2479

Compare this clearance with what you saw earlier in the 0957 image:

Zero Clearance - Mary - 2021-09-07 - 1627
Zero Clearance – Mary – 2021-09-07 – 1627

Mary can’t get far enough away, but this must suffice:

Zero Clearance - Ed Rear - 2021-09-07 - 2761
Zero Clearance – Ed Rear – 2021-09-07 – 2761

Now the driver can pass her again with more clearance:

Zero Clearance - Mary - 2021-09-07 - 1891
Zero Clearance – Mary – 2021-09-07 – 1891

I pointed to the car, then to the circle, and shouted “GO!” because neither of us wanted to be in front of that particular driver:

Zero Clearance - Ed Front - 2021-09-07 - 2540
Zero Clearance – Ed Front – 2021-09-07 – 2540

We’ll surely meet her again, ideally with more clearance.

Henceforth, we will take the middle of the lane into splitters, as cyclists should do on a “shared” roadway. I was assured by the DOT engineer who designed Raymond Avenue that it’s all “standards compliant”, so this is what NYS DOT regards as “making their highway systems safe and functional for all users”.

Having amateur radio HTs on the bikes lets us talk with each other in real time, which is a definite asset when stuff like this happens.

Not to mention having cameras here, there, and everywhere.

Elapsed time from the first to the last picture: 33 s.

For the record: blue Ford (although the ersatz fender vents seem reminiscent of an old Buick), license ANC-4273.