Order of Coordinates for Object Detection

Part 1 2022
1

Hi all,

Hope you are well. :slight_smile:

I am working on an object detection task, and the CSV file has the coordinates in the this order: ymin, xmin, ymax, and xmax.

Does fast.ai BBoxLblBlock accept input in this format: ‘xmin’, ‘ymin’, ‘xmax’, ‘ymax’

So, when reading the CSV input file, should I change the order to be this: ‘xmin’, ‘ymin’, ‘xmax’, ‘ymax’ and then, when creating the datablock with BBoxLblBlock, have the correct order of: ‘xmin’, ‘ymin’, ‘xmax’, ‘ymax’?

OR:
Should I keep the CSV file as-is and the datablock with BBoxLblBlock is still fine to have the order as: ‘xmin’, ‘ymin’, ‘xmax’, ‘ymax’ OR should it be changed to ymin, xmin, ymax, and xmax to reflect the order of the CSV file?

Thanks in advance. Much appreciated!

Zakia

2 Likes
2

Yes, you should change the order in your CSV file to xmin , ymin , xmax , ymax to match the format expected by fast.ai’s BBoxLblBlock . This way, when you create the datablock, the coordinates will be correctly interpreted.

Best Regards,
Gary Byers

3

Hello,

You should change the order of your coordinates in your CSV file to xmin, ymin, xmax, ymax. Then, when you create your DataBlock using BBoxLblBlock, use the same order (‘xmin’, ‘ymin’, ‘xmax’, ‘ymax’) in your bbox_cols argument. This ensures everything lines up perfectly.

Trying to force a mismatch between the CSV and the bbox_cols argument will likely lead to your bounding boxes being interpreted incorrectly, causing inaccurate results. Keep it consistent for a smoother workflow!

Best Regards