.. Plom documentation
   Copyright (C) 2018-2022 Andrew Rechnitzer
   Copyright (C) 2022-2025 Colin B. Macdonald
   SPDX-License-Identifier: AGPL-3.0-or-later


Scanning and uploading
======================

At this point we assume that you have printed that papers, fed them to
your students (or the other way around), and collected the completed
tests.

Scanning papers
---------------

To get the students’ work into Plom we have to get the physical papers
scanned. The precise details of how you do this will depend on the
scanning hardware that is available.  We recommend that you:

- scan in colour, using DPI of at least 200,
- do it yourself or delegate to someone trustworthy.
- staple removal is likely a bottleneck.  Options include scissors, a
  guillotine, or staple-remover.
- use good “paper hygiene”:

    - Sort papers into test-number order before scanning, and keep them in order (opinions differ on this but if something goes wrong its very valuable).
    - Keep papers in sensible and physically manageable bundles, before, during and after scanning.
      There is a strict upper limit on bundle size and page count; these exist for security reasons and far exceed what would be a sensible bundle size.
    - Have a good physical flow of papers from pre-scan to post-scan, so that each paper is scanned exactly once.
    - Give your scans clear filenames such as ``math123mt1-sec1-bundle2.pdf``.
    - You may need to find page in these hardcopies so physically label each bundle, for example with the above filename.


Uploading to the web-based server
---------------------------------

Create one or more "scanner" accounts.
Login to your server using one of those accounts.
Follow the instructions to upload bundles of papers as PDF files.


Dealing with unknown pages, extra pages, error pages, etc
.........................................................

After scanning, you likely have some "Pages that need your attention",
such as folded pages, pages without readable QR codes due to
printing/scanning troubles, extra pages using our template or even
adhoc pages such as looseleaf.

These can all be handling using the web interface.

Occasionally, you may see pages where the QR-reader has failed (hopefully
these are rare).  Folded pages are one possibility: you may
need to re-scan a page.


Collisions
..........

"Good collisions" are caused for example by re-scanning a page.
These can be dealt with using the web interface, for example by discarding one of them.
"Bad collisions" come from accidental reuse of papers e.g., from double-printing.
This is a more serious problem, see :doc:`faq`.



Technical docs
--------------

* The command-line tool :doc:`plom-cli` can be used to upload files
  from the command line.