title: Yolov5 object detection training
body: <p>Please i need you help concerning my <strong>yolov5 training process</strong> for object detection!</p>
  <p>I try to <strong>train my object detection model yolov5 for detecting small object</strong> ( scratch). For labelling my images i used roboflow, where i applied some data augmentation and some pre-processing that roboflow offers as a services. when i finish the pre-processing step and the data augmentation roboflow gives the choice for different output format, in my case it is yolov5 pytorch, and roboflow does everything for me splitting the data into training validation and test. Hence, Everything was set up as it should be for my data preparation and i got at the end the folder with data.yaml and the images with its labels, in data.yaml i put the path of my training and validation sets as i saw in the GitHub tutorial for yolov5. <strong>I followed the steps very carefully</strong> tought.</p>
  <p><strong>The problem</strong> is when the training start i get nan in the obj and box column as you can see in the picture bellow, that i don't know the reason why, can someone relate to that or give me any clue to find the solution please, it's my first project in computer vision.</p>
  <p><a href="https://i.stack.imgur.com/j9msh.png" rel="nofollow noreferrer">This is what i get when the training process starts</a></p>
  <p><a href="https://i.stack.imgur.com/Vmeyf.png" rel="nofollow noreferrer">This the last message error when the training finish</a></p>
  <p><a href="https://i.stack.imgur.com/4k1LW.png" rel="nofollow noreferrer">I think the problem comes maybe from here but i don't know how to fix it, i used the code of yolov5 team as it's in the tuto</a></p>
  <p>The training continue without any problem but the map and precision remains 0 all the process !!</p>
  <p>Ps : Here is the link of tuto i followed : <a href="https://github.com/ultralytics/yolov5/wiki/Train-Custom-Data" rel="nofollow noreferrer">https://github.com/ultralytics/yolov5/wiki/Train-Custom-Data</a></p>