Forum: support

RE: nops_eval problems [ Reply ]
By: Achim Zeileis on 2019-05-09 15:56

As for the .zip file: What happened is probably that your file

nops_scan_20190509145847.zip

does not contain _directly_

Daten.txt
S0000001.PNG
S0000002.PNG
...

but instead you now have a .zip file that contains one sub-directory "nops_scan_20190509145847/" that contains these files, i.e.,

nops_scan_20190509145847/Daten.txt
nops_scan_20190509145847/S000001.PNG
nops_scan_20190509145847/S000002.PNG
...

and nops_eval() is confused by that. I should add a check in nops_eval() to catch this situation and handle it automatically and additionally throw a more meaningful error otherwise.

So please re-zip your nops_scan file _without_ the additional sub-directory.

As for the scans: It is always device-specific what works best. I typically use black/white scanning or possibly gray levels but not color (which tends to be more error-prone). And then I play around with the best gray levels of the scanning machine. If you use recycling paper (which is a good thing, of course) you might have to make the scan a bit lighter.

Hope that helps!

nops_eval problems [ Reply ]
By: Marcelino Martínez Sober on 2019-05-09 13:17

[forum:46708]

Hello:

Althouth I still have an open question relate to inserting tables in questions, I have prepared a written exam in order to test the system before the "real" exam finding the following problems.

I have tried different scanning options and the best option (grayscale) still gives me problems in later stages. (One of my errors was using recycled paper whose color makes detection difficult)

Once I process the pdf file, and analyze the images, the Daten.txt file, included in the compressed folder contains some errors derived from the detection that make the automatic evaluation fail.
I have tried to manually correct these errors (there are few) in the Daten.txt file and compress again to generate the zip. In this case an error is generated saying
Error in nops_eval(eval = exams_eval(partial = TRUE, rule = "false"), :
nops_scan_20190509145847.zip' does not contain a 'Daten.txt' file

Interactive mode
Is it possible to use the system if there are recognition failures in some exams?

Thank you