how I get the cropped position information of roi about x, y, width, height from HailoCropper?

General
1

I could only get the cropped images, and here is a part of the gstreamer pipeline: hailocropper so-path=./libs/post_processes//cropping_algorithms/libre_id.so function-name=create_crops internal-offset=true name=cropper2 hailoaggregator name=agg2 cropper2. ! queue name=bypess2_q leaky=no max-size-buffers=30 max-size-bytes=0 max-size-time=0 ! agg2. cropper2. ! queue name=pre_reid_q leaky=no max-size-buffers=10 max-size-bytes=0 max-size-time=0 ! hailonet hef-path=./weights/repvgg_a0_person_reid_2048.hef scheduling-algorithm=1 vdevice-group-id=1 name=reid-net ! queue name=reid_post_q leaky=no max-size-buffers=10 max-size-bytes=0 max-size-time=0 ! hailofilter so-path=./libs/post_processes//libre_id.so qos=false name=hailofilter_ ! queue name=reid_pre_agg_q leaky=no max-size-buffers=10 max-size-bytes=0 max-size-time=0

2

Hey @js12459743,

When you use HailoCropper in your pipeline, you can actually pull out all the position data (x, y, width, height) for each ROI from the metadata on the cropped frames. This is super helpful when you need to know where your detections were in the original frame.

HailoCropper works pretty straightforward:

  1. Gets an input frame (usually after HailoFilter has processed it with detections)
  2. Runs its prepare_crops method to create a vector of crop ROIs
  3. Each ROI includes metadata about where it sits in the original frame
  4. Sends the cropped frames out through a separate src pad from the original

To get the position info, each cropped frame has Hailo ROI metadata with the bounding box details. You can grab the coordinates like:

HailoBBox bbox = roi->get_bbox();
float x = bbox.xmin();
float y = bbox.ymin();
float width = bbox.width();
float height = bbox.height();

For implementation in your app:

  1. Get the HailoROIPtr object from each cropped buffer
  2. Call get_bbox() on the ROI object
  3. Use the bbox methods (xmin(), ymin(), width(), height()) to get the exact coordinates

In a GStreamer pipeline, this data gets attached to each GstBuffer using Hailo’s custom metadata structures. How you extract it depends on your post-processing module (like libre_id.so).

Your post-processing code can use the Hailo metadata API to figure out where each crop was positioned in the full frame.

Bottom line - HailoCropper gives you all the position info for every crop it generates, so you can map your detections back to their original spots in the source frame.