> For the complete documentation index, see [llms.txt](https://docs.augelab.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.augelab.com/function-blocks/blocks-reference/detections-shapes/roi-processing/check-area.md).

# Check Area

This function block lets you draw a rectangular area on an image and check whether one or more point coordinates fall inside that area. It is ideal for simple region-of-interest checks and quick presence/absence detection inside a selected rectangle.

## 📥 Inputs <a href="#inputs" id="inputs"></a>

`Image Any` Reference image used as the coordinate canvas where you draw the rectangular area.

`Position Coordinate(s)` One point or a list of points to test against the selected area. Provide pixel coordinates (x, y).

## 📤 Outputs <a href="#outputs" id="outputs"></a>

`Area Rectangle` The rectangle you selected, expressed in image pixel coordinates.

`Object In Area` Boolean value indicating whether any provided point lies inside the selected rectangle.

`Detection Count` Number of input points that were found inside the selected rectangle.

## 🕹️ Controls <a href="#controls" id="controls"></a>

`Image Preview` Click and drag directly on the preview to draw a rectangular area. The preview will show the rectangle overlay in real time.

`Drag to Select` Use a click-and-drag gesture to set the top-left and bottom-right corners of the rectangle. Redrawing updates the selected area immediately.

`Overlay Display` Visual markers appear on the image for the selected rectangle and for any points that fall inside it.

## 🎨 Features <a href="#features" id="features"></a>

* Visual, interactive selection of a single rectangular region on the input image.
* Supports checking a single coordinate or a list of coordinates.
* Marks detected points inside the area with a visible marker on the preview.
* Outputs the selected rectangle and simple boolean/count results for easy downstream logic.

## 📊 How it runs <a href="#evaluation" id="evaluation"></a>

* Provide a valid image to the `Image Any` input so the preview becomes active.
* Draw the rectangle directly on the preview using click-and-drag. The selected region is interpreted in pixel coordinates of the image.
* Feed points into `Position Coordinate(s)` (single coordinate or list). On evaluation the block checks each point against the selected rectangle and returns the rectangle, whether any points are inside, and how many. The preview is updated to show the rectangle and any inside points.

## 📝 Usage Instructions <a href="#usage" id="usage"></a>

1. Connect an image source to `Image Any` so the interactive preview appears.
2. Click and drag on the preview to draw the area you want to monitor.
3. Provide point coordinates to `Position Coordinate(s)` (for example, output from a detection block).
4. Run the scenario; results appear as `Area Rectangle`, `Object In Area`, and `Detection Count`. The preview displays markers for any points inside the rectangle.

## 💡 Tips and Tricks <a href="#tips-and-tricks" id="tips-and-tricks"></a>

* To get point coordinates from automatic detectors, connect outputs from blocks such as `Find Object` or `Object Detection` (or `Object Detection - Custom`) into the `Position Coordinate(s)` input.
* If you need multiple crop areas or more flexible ROI shapes, consider using `Image ROI Select` or `Image ROI Polygon Multi` and then feed results into specialized filtering blocks.
* Use `Draw Rectangle` or `Draw Point` to create a combined visual output for reports or presentations after the check.
* For higher-level filtering (e.g., checking one rectangle against many detected rectangles), combine with `Rectangles in Rectangle` to refine results further.
* If coordinates come from pose or keypoint detectors, try pairing with `Pose Estimation` or `Hand Pose Estimation` to check specific body or hand keypoints inside the area.

## 🛠️ Troubleshooting <a href="#troubleshooting" id="troubleshooting"></a>

* No preview appears: ensure a valid image is connected to `Image Any` and run at least once so the preview is initialized.
* Coordinates not detected as inside: verify that coordinates are in pixel format (x, y) matching the image resolution, not normalized values.
* Single-point vs list: the block accepts a single coordinate or a list—if your source supplies a different structure, convert it to a simple (x, y) or a list of (x, y) pairs before connecting.