# Hull Convex This function block calculates a convex enclosing contour around a provided contour and returns visual and numeric results useful for shape analysis. ## đŸ“Ĩ Inputs `Image` The source image used for visualization and measurements. `Contour` The input contour (shape) to enclose with a convex hull. ## 📤 Outputs `Image` The source image annotated with the original contour and its convex hull. `Contour` The calculated convex hull contour returned as a shape. `Center` The centroid position of the convex hull (x, y). `Area` The area of the convex hull. ## 🕹ī¸ Controls This function block has no interactive controls. It runs automatically when inputs are provided. ## đŸŽ¯ What it does * Computes an enclosing convex hull for the provided contour. * Draws both the original contour and the convex hull onto the image for clear visual comparison. * Calculates the hull area and its centroid coordinates for downstream measurements or logic. * Returns both annotated visual output and structured shape/measurement outputs for further processing. ## 📝 Usage Instructions 1. Provide the original image into the `Image` input so the block can produce an annotated visual result. 2. Provide a detected contour into the `Contour` input to compute its convex hull. 3. Use the returned `Image` to preview hull vs original contour, use `Contour`/`Center`/`Area` for measurements, filtering, or reporting. ## 📊 Evaluation When run, the block examines the provided contour, produces a convex hull shape, annotates the image with both shapes, computes the hull centroid and area, and outputs these four results: annotated image, hull contour, center point, and area. ## 💡 Tips and Tricks * If you don't yet have a contour, use the `Find Contour` block or `Find Object` block to get contours from an image before feeding them into this block. * To simplify complex contours before hull calculation, consider `Approximate Contour` to reduce point count and improve performance. * Use `Minimum Rectangle`, `Minimum Circle`, or `Minimum Ellipse` after this block when you need alternative enclosing shapes or additional geometric descriptors. * Preprocess the image with `Image Threshold`, `Image Adaptive Threshold`, or `Blur` to get cleaner contours for more reliable hull computation. * Crop or focus analysis using `Image ROI`, `Image ROI Select`, or `Image ROI Polygon` so the contour extraction and hull calculation target the area of interest. * Visualize results in a larger window using `Show Image` and save important frames with `Image Logger` or `Image Write` for documentation or offline review. ## 🛠ī¸ Troubleshooting * If the output `Contour` is empty or the `Area` is zero: ensure the input `Contour` is valid and contains enough points. Use contour-producing blocks (`Find Contour`, `Find Object`) and verify their outputs. * If annotations look misplaced after image scaling: ensure the same image dimensions are used throughout the pipeline (use `Image Resize` or `Image Resizer` consistently). * If unwanted background shapes produce large hulls: try preprocessing (thresholding, blurring) and use ROI blocks to focus on the object of interest. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.augelab.com/function-blocks/detections-shapes/shape-analysis/hull-convex.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.