# Challenges with Detection Stitch **URL:** \ **Category:** 🤝 Community Help\ **Created:** [November 2, 2025, 9:25pm UTC](https://discuss.roboflow.com/t/challenges-with-detection-stitch/11412 "2025-11-02T21:25:26Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![totoro](https://yyz1.discourse-cdn.com/flex029/user_avatar/discuss.roboflow.com/totoro/32/8606_2.png) [@totoro](https://discuss.roboflow.com/u/totoro)\ **Post date:** [November 2, 2025, 9:25pm UTC](https://discuss.roboflow.com/t/challenges-with-detection-stitch/11412/1 "2025-11-02T21:25:26Z")
- **Project Type:** Workflow for segmentation - **Operating System & Browser:** Mac OS 15.6.1 & Google Chrome - **Project Universe Link or Workspace/Project ID:** [Link to workflow](https://app.roboflow.com/workflows/embed/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ3b3JrZmxvd0lkIjoiOE1Ed0ZUSlFPWUh5c1NlZTFqSm0iLCJ3b3Jrc3BhY2VJZCI6InpSbXNOV3h3UWxlMk9jTVJJajBvankwajhQSjMiLCJ1c2VySWQiOiJ6Um1zTld4d1FsZTJPY01SSWowb2p5MGo4UEozIiwiaWF0IjoxNzYyMTE4MjMyfQ.Z5-Mnj2uT_urRfAJ1ay1TTpZgc-LNe6YqL2O-h_89r8) Hello, I will preface by saying that I am an amateur with coding and Roboflow. My ultimate goal is to train a model that can help me segment and characterize the size/shape of particles in a microscope image for my graduate research. I am still trying to train my model, but it seems like an arduous task to draw polygons around thousands of objects. My new strategy is to make a workflow that will help me annotate images that I can use to train my model. To do this, I am trying to segment images with the SAHI method to recognize large objects and very fine features (~10x10 pixels). I initially slice the images then apply the model that I trained. However, every time I try to stitch my images back together, I get the following message: “_Dimensions for crops is expected to be saved in data key parent\_dimensions of sv.Detections, but could not be found. Probably block producing sv.Detections lack this part of implementation or has a bug_.’ Am I missing something? ![workflow](https://canada1.discourse-cdn.com/flex029/uploads/roboflow1/original/2X/5/5ee119e16b04126d0b5e91972b95f8db25bd8ecb.png) ---
**Author:** ![totoro](https://yyz1.discourse-cdn.com/flex029/user_avatar/discuss.roboflow.com/totoro/32/8606_2.png) [@totoro](https://discuss.roboflow.com/u/totoro)\ **Post date:** [November 2, 2025, 9:27pm UTC](https://discuss.roboflow.com/t/challenges-with-detection-stitch/11412/2 "2025-11-02T21:27:20Z")
This is an example image that I am trying to segment. If somebody has a suggestion for a more efficient way to annotate all of the particles below, I would greatly appreciate that too! ![0% PVA, 15% DOSS 4x_17](https://canada1.discourse-cdn.com/flex029/uploads/roboflow1/original/2X/1/1468aa98ec6fbd0d3cb3480be08d1c5ca8d191e5.jpeg) ---
**Author:** ![Automatez](https://yyz1.discourse-cdn.com/flex029/user_avatar/discuss.roboflow.com/automatez/32/8971_2.png) [@Automatez](https://discuss.roboflow.com/u/Automatez)\ **Post date:** [November 3, 2025, 3:35pm UTC](https://discuss.roboflow.com/t/challenges-with-detection-stitch/11412/3 "2025-11-03T15:35:03Z")
You’re on the right track! Slicing and detecting is a good strategy for small detections. For your Detections Stitch, double check that it is using the “Input\>Image” as the Reference Image (and not the Image Slicer images.) That could be one issue. But then as you suggest, your main question/goal is about how to annotate all those. I tried the Auto-Label function (I’m guessing you did as well) to create an initial set of annotations with segmentation. I found it was only getting about 75% of the detections as you can see below. So that would generate a model to help, but probably not as great as you hoped given all the annotating you have to do. ![chrome_619dYeGVQb](https://canada1.discourse-cdn.com/flex029/uploads/roboflow1/original/2X/9/978b5d50bb6f784f386f324744239e9285ef89ee.jpeg) If you really want to minimize annotating work, I wonder if you could switch strategies and do an object detection model and then build a classification model to run against those individual detections. So it could decide if it’s an air bubble vs a pollen grain. (Or maybe even a segmentation model.) I threw just 10 test images into their site [https://rapid.roboflow.com/](https://rapid.roboflow.com/) and when I moved the sensitivity slider I got almost all the detections. You can then manually fix the few that are missed or wrong as sometimes it groups 3 or 4 as a single detection. (Note, you need to “Find Objects”, move the slider, then “Approve” and THEN you can still do edits to make it 100% accurate. Be sure to do this for every image before the “Review Model” step.) Then you generate a model on that. Now you’ve quickly isolated all the items on the slide image and can do what you need from there (including stitch back to the original image). ![chrome_G64pLhMqrC](https://canada1.discourse-cdn.com/flex029/uploads/roboflow1/original/2X/e/ed5a650b9a8f2757f2b2b7a2f90526c551424159.jpeg) ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex029/uploads/roboflow1/original/1X/bb6edbfa56d0cf2ee603f061e9e09103502cc8cc.png) [@system](https://discuss.roboflow.com/u/system)\ **Post date:** [November 24, 2025, 3:35pm UTC](https://discuss.roboflow.com/t/challenges-with-detection-stitch/11412/4 "2025-11-24T15:35:47Z")
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