duerig
commented
6 years ago The biggest thing to impact performance is the speed of the external storage device. Either your memory card or USB drive. This has a noticeable and immediate impact. With a fast memory card for external storage, I find that the processing time is almost always less than the time to flip the page.
The SD cards on the cameras themselves may have an impact as well, though I have not tested this extensively. So if you try speeding them up, let me know what if any impact you see.
The SD card on the Raspberry Pi does not have an impact on the speed at all. The only thing this might affect is startup time (how long it takes to boot into Pi Scan).
The typical setup that I use for this involves two cheap class 4 SD cards for the cameras, one cheap class 4 card for the Raspberry Pi. And one expensive Class 10 U3 card for external storage. Note that All of this goes over USB 2. So that will be the upper speed limit regardless.
Just a quick note regarding camera failure handling. A bug has crept into the most recent build which impedes fast failure handling in some cases. After a failure it will sometimes see the cameras as gphoto (DSLR) cameras instead of CHDK (ELPH 160) cameras. I am working on fixing this and will release version 1.6 with a fix when it is ready. My clever code for auto-detecting this was not as clever as I thought.
meelash
Dmole
Now that I have a complete workflow functioning for scanning books and have some experience with it, I would like to increase the efficiency. There are two glaring bottlenecks, currently, one being errors that stop the flow and, the other, general slow performance. I'll be posting another issue to try to isolate the cause of those errors that I get and fix them. Here, I'd like to address the performance problems I'm finding.
Ideally, I think, one would expect the mechanical ability of the operator to be the limiting factor in maximum speed of scanning as opposed to the software. But I find that I am limited by software when I'm scanning.
When I hit the Scan button, almost instantly I hear the cameras fire, and I can begin moving to the next page. But then the majority of the time I can easily complete turning the page and lifting the book back up to the platen well before Pi Scan is ready to capture the next scan. The interesting thing is there seems to be quite a bit of variability in the time spent on the "Capturing..." screen, sometimes it matches my mechanical speed, and sometimes, I am waiting for some seconds.
The performance hit I am talking about is I would estimate that I could easily do upward of 1000 pages per hour physically, but currently I am maybe getting 600-700 even not counting the errors that I alluded to.
I guess the first question I have is, are my experiences typical? Or is there something I am doing wrong?
My system is a raspberry pi2 with touch screen, powershot IXUS 160 cameras, cheap class 4 memory cards (I thought these didn't matter? If necessary I can upgrade them to test).