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. You can, however, set the selected space for a region to a different space than the one in which the tool runs. This following figure shows an example of running tools and regions in different spaces.

You may, for example, have a vision application that requires you to measure objects in real-world units and also track specific features as they change from image to image. Suppose you want a robotic arm to pick up brackets that move along a conveyor belt and into view of an inspection camera. Your application must calculate distances in some physical unit determined by calibration. You must also track the location and orientation of bracket features in each image, so that the robot can grasp the bracket. To get tool results in real-world units but maintain a fixtured space, set the tool to run in calibrated space and use fixtured space as the selected space of the tool’s input region.

By using different selected space names for the tool and region of interest, you can often avoid writing code to map tool results from one space to another desired space. You should note that, in fact, some vision tool results, such as the CogBlobTool tool’s Perimeter and Area results, are very difficult to map from the space in which they were originally run to a more convenient space.

You can determine if you should use a different selected space for your tool and region of interest by answering the following two questions.

• In what coordinate space do you want your tool's results?
  • To locate the physical coordinates of a part (for example, in robotic picking or placing applications), you would normally use calibrated space.
  • For 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?
  • For the tool's region of interest to remain fixed to an object that may move from image to image, set the region's selected space name to the object's fixtured space.

If you answered with 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.