Ever wonder what your desk surface looks like up close? No. No one has. Not even [Sprite_tm], but upon disassembling his optical mouse and discovering its 18×18 CCD he decided to put it to use (well, a different use). The optical chip outputs serial information to the USB chip in the mouse. [Sprite_tm] wired the optical chip to a parallel port and wrote a simple program to interpret the data. Not really useful, but it does generate some interesting pictures. Program provided, natch.
SplineScan is a cross platform 3D scanning solution. While the target object is rotating on a motion controlled turntable a laser is projected on it. A camera collects images of each step of the rotation. Using simple trig the individual frames’ line data can then be used to construct a 3D model. Andrew Lewis is in the process of porting the model generator to C from VB, but it can already be run in Ubuntu using WINE. If all goes well he will be doing a live demo at LUGRadio Live with detailed source to follow soon after. He expects the final scanner to only cost approx. $90. Sounds like a lot of fun. Thanks for sending it in Andrew.
this is really neat, a fellow starting playing around with his scanner and actually made it in to a digital camera. now you might be thinking, why? this was done back in 2000 when 2mp cameras were thousands of dollars, all for under $100, i’m going to pick upa cheap $49 scanner and see what’s possible now
Supercon is the Ultimate Hardware Conference and you need to be there! We’ve got a stellar slate of speakers this year — way too many to feature in one post. So here’s your first taste, and a reminder that Supercon will sell out so get your tickets now before it’s too late.
In addition to the full-length talks, we’ve got a series of Lightning Talks, so if you want to share seven minutes’ of insight with everyone there, please register your Lightning Talk idea now.
But Supercon has a lot more than just talks! The badge heavily features Supercon Add-Ons, and we want to see the awesome SAOs you are working on. There will be prizes, and we’ll manufacture four of our favorite designs in small batches for the winners, and make a full run for Hackaday Europe in 2025. Want to know more about SAOs? They’re the ideal starter PCB project.
Continue reading “2024 Hackaday Superconference Speakers, Round One”
It seems like only yesterday we covered a project using QR codes to archive data on paper (OK, it was last Thursday), so here’s another way to do it, this time with a dedicated codec using the full page. Optar or OPTical ARchiver is a project capable of squeezing a whopping 200 Kb of data onto a single A4 sheet of paper, with writing and reading achieved with a standard laser printer and a scanner. It’s a bit harder than you might think to get that much data on the page, given that even a 600 DPI printer can’t reliably place every dot each time. Additionally, paper is rarely uniform at the microscopic scale, so Optar utilizes a forward error-correcting coding scheme to cater for a little irregularity in both printing and scanning.
The error-correcting scheme selected was an Extended Golay code (24, 12, 8), which, interestingly, was also used for image transmission by the NASA Voyager 1 and 2 missions. In information theory terms, this scheme has a minimum Hamming Distance of 8, giving detection of up to seven bit errors. This Golay code implementation is capable of correcting three-bit errors in each 24-bit block, with 12 bits available for payload. That’s what the numbers in those brackets mean.
Another interesting problem is paper stretch during printing. A laser printer works by feeding the paper around rollers, some of which are heated. As a printer wears or gets dirty, the friction coefficient along the rollers can vary, leading to twisting and stretching of the paper during the printing process. Water absorbed by the paper can also lead to distortion. To compensate for these effects, Optar regularly inserts calibration targets throughout the bit image, which are used to locally resynchronize the decoding process as the image is processed. This is roughly similar to how the alignment patterns work within larger QR codes. Finally, similar to the position detection targets (those square bits) in QR codes, Optar uses a two-pixel-wide border around the bit image. The border is used to align to the corners well enough to locate the rows of bits to be decoded.
In the distant past of last week, we covered a similar project that uses QR codes. This got us thinking about how QR codes work, and even if encoding capacity can be increased using more colors than just black and white?
Thanks to [Petr] for the tip!
QR codes are used just about everywhere now, for checking into venues, ordering food, or just plain old advertising. But what about data storage? It’s hardly efficient, but if you want to store your files in a ridiculous paper format—there’s a way to do that, too!
QR-Backup was developed by [za3k], and is currently available as a command-line Linux tool only. It takes a file or files, and turns them into a “paper backup”—a black-and white PDF file full of QR codes that’s ready to print. That’s legitimately the whole deal—you run the code, generate the PDF, then print the file. That piece of paper is now your backup. Naturally, qr-backup works in reverse, too. You can use a scanner or webcam to recover your files from the printed page.
Currently, it achieves a storage density of 3KB/page, and [za3k] says backups of text in the single-digit megabyte range are “practical.” You can alternatively print smaller, denser codes for up to 130 KB/page.
Is it something you’ll ever likely need? No. Is it super neat and kind of funny? Yes, very much so.
We’ve seen some other neat uses for QR codes before, too—like this printer that turns digital menus into paper ones. If you’ve got your own nifty uses for these attractive squares, let us know!
Have you ever scanned old negatives or print photographs? Then you’ve probably wondered about the resolution of your scanner, versus the resolution of what you’re actually scanning. Or maybe, you’ve looked at digital cameras, and wondered how many megapixels make up that 35mm film shot. Well [ShyStudios] has been pondering these very questions, and they’ve shared some answers.
The truth is that film doesn’t really have a specific equivalent resolution to a digital image, as it’s an analog medium that has no pixels. Instead, color is represented by photoreactive chemicals. Still, there are ways to measure its resolution—normally done in lines/mm, in the simplest sense.
[ShyStudios] provides a full explanation of what this means, as well as more complicated ways of interpreting analog film resolution. Translating this into pixel equivalents is messy, but [ShyStudios] does some calculations to put a 35mm FujiColor 200 print around the 54 megapixel level. Fancier films can go much higher.
Of course, there are limitations to film, and you have to use it properly. But still, it gives properly impressive resolution even compared to modern cameras. As it turns out, we’ve been talking about film a lot lately! Video after the break.
Continue reading “How Much Resolution Does Film Really Have?”
