Scripts for data acquisition with paper based surveys
Clone or download
Menuka5 and weblate Translated using Weblate (Sinhala)
Currently translated at 1.6% (3 of 187 strings)
Latest commit d64b9ae Oct 8, 2018


This Program can be used to carry out paper based surveys.

SDAPS uses a specialised LaTeX class to define questionnaires. This is tightly integrated and is an easy way to create machine readable questionnaires.

After this, the program can create an arbitrary number of (unique) questionnaires that can be printed and handed out. After being filled out, you just scan them in, let sdaps run over them, and let it create a report with the results.


Depending on what part of SDAPS you use, different dependencies are required.

general (including recognize):

  • Python 3.6
  • distutils and distutils-extra
  • python3-cairo (including development files)
  • libtiff (including development files)
  • pkg-config
  • zbarimg binary for "code128" and "qr" styles
  • python3 development files

graphical user interface (gui):

  • GTK+ and introspection data
  • python3-gi

reportlab based reports (report):

  • reportlab
  • Python Imaging Library (PIL)

LaTeX based questionnaires (setup_tex/stamp):

  • pdflatex and packages:
    • PGF/TikZ
    • translator (part of beamer)
    • and more

LaTeX based reports:

  • pdflatex and packages:
    • PGF/TikZ
    • translator (part of beamer)
  • siunitx

Import of other image formats (convert, add --convert):

  • python3-opencv
  • Poppler and introspection data
  • python3-gi

Debug output (annotate):

  • Poppler and introspection data
  • python3-gi


You can install sdaps using "./ install". The C extension will be compiled automatically, but of course you have to have all the dependencies installed for this to work.

Please note that this git repository uses submodules to pull in the LaTeX code. This means you need to run $ git submodule init and then run $ git submodule update to checkout and update the repository after a pull.

Alternatively, do the initial clone using "git clone --recursive".

Standalone execution

As an alternative to installing sdaps it is also supported to run it without installation. To do this run "./ build" to build the binary modules and translation. After this execute sdaps using the provided "" script in the toplevel directory.


Please run sdaps with "--help" after installing it for a list of commands. Also check the website for some examples.

Quality of the recognition

The quality of the recognition in SDAPS is quite good in my experience. There is a certain amount of wrong detections, that mostly arise from people not checking or filling out the boxes correctly. For example:

  • The cross is not inside the checkbox, but next to it
  • People cross the same box multiple times
  • People use very thick pens
  • Filling out is not done properly

As you can see, most of the errors arise from the possibility to correct wrong marks by filling out checkboxes. SDAPS tries to be smart about this by using different heuristics to detect the case, but it is not foolproof.

Suggestions on how to decrease the error rate are of course welcome.

Matrix Errors

It can happen that SDAPS is not able to calculate the transformation matrix which transforms the pixel space of the image into the mm coordinate system used internally. If this happens the affected pages cannot be further analysed. It is usually possible to manually correct them using the GUI, but that can be quite tedious.

See also TROUBLESHOOTING for some more information.