# ROI Options Following a Blue Locate Tool

When a Blue Locate Tool is the preceding tool, the tool provides a transform which a downstream tool can use to fixture where the region of interest of the tool is located in the image.

To specify a region of interest for the downstream tool, use these options:

- One or more features
- A match
- A node model A specific spatial arrangement of a set of features (Blue Locate and Blue Read tools only.) During a post-processing step, the Blue Locate and Blue Read tools can fit all of the features detected in an image to the models defined for the tool. The overall pose and identity of the model is then returned.
- A layout model

## ROI from a Feature

Use the individual features defined in a Blue Locate Tool to provide the region of interest for downstream tools. Each feature A feature is a visually distinguishable area in an image. Features typically represent something of interest for the application (a defect, an object, a particular component of an object). provides a five degree of freedom (DOF) transform (X translation, Y translation, rotation, X scale, and Y scale).

The feature also determines the size of the ROI The Region of Interest (ROI) defines the area of operation for the tool. The ROI preserves the positions, angles, stretch and skew of the original image.. The percentage of the ROI is based on the width and height of the feature.

1. Select Feature.

2. Click the down arrow on Target to reveal a drop-down menu of a list of the features defined by the tool. Matched Only only returns features that are part of a model.

   Note: By clicking the lock icon and disabling it, you can create your own expression for a feature or match filter. You can construct custom filters with the syntax feature[] or match[], such as feature[id='featurename'] or match[name='modelname']. The default setting is an empty filter, which matches all features.

3. Select one or more features or Matched Only.

4. The Target field displays the filter applied to generate views. You can adjust the ROI to fit the area to inspect.

## ROI from a Match

The Matched option allows you to specify that an ROI is only created if the preceding Blue Locate Tool produces a matching node or layout model.

## ROI from a Node or Layout Model

If a node model or a layout model is configured, a tool following a Blue Locate Tool can use a node or layout model to adjust the orientation of their ROI.

A node model provides a five degree of freedom (DOF) transform (X translation, Y translation, rotation, X scale, and Y scale). The node model also determines the size of the ROI. The percentage of the ROI is based on the width and height of the node model.

You can also use a layout model which shows the various regions of the model as views for the downstream tool.

In Expert Mode, the Scale setting is available, which scales the ROI to match the model reference frame. By default, the ROI does not scale and uses the original image pixel size. In addition, you can also specify the scale setting applies to matches only.

By pressing the lock icon and disabling it, you can create your own expression for a feature or match filter. You can construct custom filters with the syntax feature[] or match[], such as feature[id='featurename'] or match[name='modelname']. The default setting is an empty filter, which matches all features.