# Running Vision Tools in Fixtured Regions

VisionPro tools always interpret inputs and report results in the selected space of the input image. By default, regions of interest (ROIs) are also interpreted in the selected space of the input image. However, you can set the selected space for a region to a different space than the one in which the tool runs.

Suppose, for instance, that your application requires that you run your vision tool in calibrated space in order to measure results in real-world units, yet also maintain a region of interest affixed to a part within the acquired image. You want a robotic arm to pick up brackets and therefore your application must calculate distances in some calibrated unit, such as microns. You must also track the bracket as it moves in each image, so the robot can determine the proper orientation with which to grasp the bracket.

To accomplish this, you run your vision tool in the coordinate space in which you want your results reported. The selected space name of the input image determines the space in which the tool runs. For the N-point calibration and fixturing tools, you can also specify which space name the tool sets as the selected space name of the output image. To choose the space to output for the N-point calibration or fixturing edit controls in QuickBuild, you use the Space to Output dropdown list on the Settings tab. You then set a different selected space name for the region in which the tool works. For example, in QuickBuild, you choose the selected space name for a region on the tool edit control's Region tab using the Selected Space Name dropdown list.

The following questions can help you determine if you should use a different selected space for your tool and region of interest.

- In what coordinate space do you want your tool's results? To locate the physical coordinates of a part (for example, for robotic picking or placing), you would use calibrated space. If you are measuring relative distances, you can use fixtured space just as well.
- In what region of the input image do you want the tool to run? If you want the tool's region of interest to be fixed to an object that may move from image to image, then set the region's selected space name to the object's fixtured space.

If you chose the same selected space for both questions, you do not need to set different selected spaces. Otherwise, you must specify separate spaces for the tool and region of interest.

This technique saves you the effort of writing code to map tool results from one space to another desired space. In fact, some vision tool results, such as the Blob tool Perimeter result can be difficult or impossible to map out of the space in which they were originally run.