Bug report #19594

Updated by Jürgen Fischer almost 4 years ago

[To see this problem and others with more context, check #19584.] https://issues.qgis.org/issues/19584.]

I had three 400MB 1-meter DEM .tif files, and RiverGIS only lets you query one file name per project, so I wanted to consolidate them.

I tried Raster -> Miscellaneous -> Merge, but got a Memory Error every time. It did write the output .tif files, with the size expected, but they were solid black.

I cut the file size a bit, but Merge still got a memory error each time. And, for each new try, I found I had to close the Merge window and start over from the QGIS menu bar. If I just edited a setting and tried again, I got "Incorrect parameter value for INPUT". It would still show the files selected, and re-selecting the input files didn't help.

Win 10 Resource Monitor showed zero memory faults, and just a tiny blip from 41% to 51% memory used, for these "Memory Error" tries, so I don't think it was a hardware limitation.

I found a way to cut the file sizes more severely...

I checked the Merge command before clicking run this time:

gdal_merge.bat ot Float32 -of GTiff -o "C:/Users/loren/Giant Files/HEC-RAS Dam Break/QGIS Projects/FEMA808/DEM_2226_clip_man_merge.tif" --optfile C:/Users/loren/AppData/Local/Temp/processing_b1a1b0b73d594cc4a2747620a75d7b50\mergeInputFiles.txt

I was a bit suspicious of all the '/' dividers being valid in Windows... The file did exist:
But it was blank before I clicked "go".

But it worked! With 225MB of input data instead of 955MB (or 1201MB input which had made an all-black 1565MB output file).

After the operation completed, the mergeInputFiles.txt file listed my input files.

Is this memory error a bug? Or an inherent limitation? Could there be a more informative error message, showing where the limit is and how much data could be handled? Maybe some documentation if there is a fixed limit?

In any case, it seems the "Incorrect parameter value for INPUT" error is a bug. Shouldn't we be able to edit a dialog and try again, without having to enter all the settings again?