Size Measurement

Class: SizeMeasurementBlockV1

Source: inference.core.workflows.core_steps.classical_cv.size_measurement.v1.SizeMeasurementBlockV1

The Size Measurement Block calculates the dimensions of objects relative to a reference object. It uses one model to detect the reference object and another to detect the objects to measure. The block outputs the dimensions of the objects in terms of the reference object.

• Reference Object: This is the known object used as a baseline for measurements. Its dimensions are known and used to scale the measurements of other objects.
• Object to Measure: This is the object whose dimensions are being calculated. The block measures these dimensions relative to the reference object.

Block Usage

To use the Size Measurement Block, follow these steps:

1. Select Models: Choose a model to detect the reference object and another model to detect the objects you want to measure.
2. Configure Inputs: Provide the predictions from both models as inputs to the block.
3. Set Reference Dimensions: Specify the known dimensions of the reference object in the format 'width,height' or as a tuple (width, height).
4. Run the Block: Execute the block to calculate the dimensions of the detected objects relative to the reference object.

Example

Imagine you have a scene with a calibration card and several packages. The calibration card has known dimensions of 5.0 inches by 3.0 inches. You want to measure the dimensions of packages in the scene.

• Reference Object: Calibration card with dimensions 5.0 inches (width) by 3.0 inches (height).
• Objects to Measure: Packages detected in the scene.

The block will use the known dimensions of the calibration card to calculate the dimensions of each package. For example, if a package is detected with a width of 100 pixels and a height of 60 pixels, and the calibration card is detected with a width of 50 pixels and a height of 30 pixels, the block will calculate the package's dimensions as:

• Width: (100 pixels / 50 pixels) * 5.0 inches = 10.0 inches
• Height: (60 pixels / 30 pixels) * 3.0 inches = 6.0 inches

This allows you to obtain the real-world dimensions of the packages based on the reference object's known size.

Watch the video tutorial

Type identifier

Use the following identifier in step "type" field: roboflow_core/size_measurement@v1to add the block as as step in your workflow.

Properties

Name	Type	Description	Refs
name	str	Enter a unique identifier for this step..	❌
reference_predictions	List[Any]	Reference object used to calculate the dimensions of the specified objects. If multiple objects are provided, the highest confidence prediction will be used..	✅
reference_dimensions	Union[List[float], Tuple[float, float], str]	Dimensions of the reference object in desired units, (e.g. inches). Will be used to convert the pixel dimensions of the other objects to real-world units..	✅

The Refs column marks possibility to parametrise the property with dynamic values available in workflow runtime. See Bindings for more info.

Available Connections

Compatible Blocks

Check what blocks you can connect to Size Measurement in version v1.

• inputs: Keypoint Detection Model, Clip Comparison, VLM as Classifier, CSV Formatter, Segment Anything 2 Model, Florence-2 Model, Roboflow Dataset Upload, LMM For Classification, Perspective Correction, Twilio SMS Notification, Google Gemini, Detections Stitch, Slack Notification, Email Notification, Local File Sink, Florence-2 Model, YOLO-World Model, Dimension Collapse, Detections Merge, Instance Segmentation Model, Google Vision OCR, Object Detection Model, Llama 3.2 Vision, Multi-Label Classification Model, Detections Filter, CogVLM, Roboflow Dataset Upload, VLM as Detector, Dynamic Zone, Velocity, Clip Comparison, Detections Classes Replacement, Path Deviation, Template Matching, Path Deviation, Dynamic Crop, Object Detection Model, Moondream2, Webhook Sink, Roboflow Custom Metadata, Byte Tracker, OpenAI, Detections Stabilizer, Detections Consensus, Line Counter, Time in Zone, OpenAI, Time in Zone, Buffer, Stitch OCR Detections, Anthropic Claude, Overlap Filter, PTZ Tracking (ONVIF).md), Size Measurement, Detections Transformation, OpenAI, Detection Offset, Single-Label Classification Model, Byte Tracker, Instance Segmentation Model, Model Monitoring Inference Aggregator, Bounding Rectangle, Byte Tracker, VLM as Detector, LMM, OCR Model
• outputs: Path Deviation, VLM as Classifier, Polygon Zone Visualization, Halo Visualization, Keypoint Detection Model, Label Visualization, Color Visualization, Clip Comparison, Object Detection Model, Webhook Sink, Mask Visualization, Corner Visualization, VLM as Classifier, Florence-2 Model, Cache Set, Circle Visualization, LMM For Classification, Perspective Correction, Google Gemini, Detections Consensus, Grid Visualization, Line Counter, Classification Label Visualization, Time in Zone, OpenAI, Trace Visualization, Time in Zone, Email Notification, Florence-2 Model, Bounding Box Visualization, Buffer, Crop Visualization, YOLO-World Model, Anthropic Claude, Instance Segmentation Model, Reference Path Visualization, Size Measurement, Object Detection Model, Llama 3.2 Vision, Line Counter, Keypoint Visualization, OpenAI, Keypoint Detection Model, Ellipse Visualization, Triangle Visualization, Line Counter Visualization, Instance Segmentation Model, VLM as Detector, Dot Visualization, VLM as Detector, Path Deviation, Clip Comparison, Polygon Visualization

Input and Output Bindings

The available connections depend on its binding kinds. Check what binding kinds Size Measurement in version v1 has.

Bindings

• input

  • object_predictions (Union[instance_segmentation_prediction, object_detection_prediction]): Model predictions to measure the dimensions of..
  • reference_predictions (Union[instance_segmentation_prediction, object_detection_prediction, list_of_values]): Reference object used to calculate the dimensions of the specified objects. If multiple objects are provided, the highest confidence prediction will be used..
  • reference_dimensions (Union[list_of_values, string]): Dimensions of the reference object in desired units, (e.g. inches). Will be used to convert the pixel dimensions of the other objects to real-world units..

• output

  • dimensions (list_of_values): List of values of any type.

Example JSON definition of step Size Measurement in version v1

{
    "name": "<your_step_name_here>",
    "type": "roboflow_core/size_measurement@v1",
    "object_predictions": "$segmentation.object_predictions",
    "reference_predictions": "$segmentation.reference_predictions",
    "reference_dimensions": [
        4.5,
        3.0
    ]
}