# Get Meter Arc Points (Get Meter Arc Points (ROI)) (G Dataflow)

Calibrates the meter or gauge using the initial and the full-scale position of the needle.

It calculates the position of the base of the needle and the arc traced by the tip of the needle.

## image in

Reference to the source image.

## ROI descriptor

ROI drawn by the user to identify the initial position of the needle and the full-scale position of the needle. The origin of each line must be the tip of the needle.

### Global Rectangle

Coordinates of the bounding rectangle.

### Contours

Individual shapes that define an ROI.

#### ID

Object specifying if contour is the external or internal edge of an ROI.

#### Type

Shape type of the contour.

#### Coordinates

Relative position of the contour.

## error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

## image out

Reference to image in.

## needle base

Cluster containing the coordinates of the base of the needle.

## arc points

Array of point clusters containing the coordinates of the points along the arc traced by the tip of the needle.

## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application