I'm in my OPENCV_ROOT folder and running the following command in Win-x64:
opencv_createsamples -bgcolor 0 -bgthresh 0 -maxxangle 1.1 -maxyangle 1.1
maxzangle 0.5 -maxidev 40 -w 80 -h 40
-img ABSOLUTE_PATH_TO_POSITIVE_IMAGES_FOLDER\car.jpg
-bg ABSOLUTE_PATH_TO_PROJECT\negatives.txt
-vec ABSOLUTE_PATH_TO_SAMPLES_FOLDER\car.jpg.vec
-num 125
My negatives.txt looks like this:
negative_images\city01_02.jpg
negative_images\city01_04.jpg
negative_images\city01_05.jpg
negative_images\city01_06.jpg
negative_images\city01_07.jpg
This is my output:
Info file name: (NULL)
Img file name: ABSOLUTE_PATH_TO_POSITIVE_IMAGES_FOLDER\car.jpg
Vec file name: ABSOLUTE_PATH_TO_SAMPLES_FOLDER\car.jpg.vec
BG file name: ABSOLUTE_PATH_TO_PROJECT\negatives.txt
Num: 125
BG color: 0
BG threshold: 0
Invert: FALSE
Max intensity deviation: 40
Max x angle: 1.1
Max y angle: 1.1
Max z angle: 0.5
Show samples: FALSE
Width: 80
Height: 40
Create training samples from single image applying distortions...
Invalid background description file.
What's invalid about my negatives collection file (negatives.txt)? I tried listing the files within it both with absolute paths and with relative paths. I'm following this tutorial.
Problem solved! The issue was simply that I had written the collection file names in Notepad++, and it all seemed fine. But when I happened to open the same file in notepad, I noticed there were no newlines after each image filename! When I added the newlines, and ran the command, the samples got created without errors!