Point Measurements


The Point Measurement tool measures a collection of point coordinates and values on an image. In addition to reporting the pixel value, or "intensity", the pixel coordinates are reported in both (column,row) and world coordinates if the image has a world coordinate calibration. The coordinates are marked using the mouse crosshair or may be precision centroid coordinates computed near the clicked point. This command is like the Centroid measurement affiliated with the Image Cursor except this command operates from a toolbar and the the points are persistent until you leave the Points mode by closing the toolbar. This command allows many points to be drawn on the image whereas the centroid marks only one point at a time . Results are reported in the Points Measurement Pane. The toolbar opens in Marking Mode with the top button active. Marker properties are set in the Marker Properties dialog opened from the button on the Points toolbar. Points may also be measured using the CMeasurePoints class in the Pro Script Module. See theMira Pro x64 Script User's Guide.

The following picture shows an Image Window with several points marked on the image. Notice the Point Measurements Toolbar docked on the left border of the Image Window.

The 3 points marked above created a Points Measurement Pane where the results are listed. Results can also be diverted to a top-level Report Window using the option in the Marker Properties dialog opened using the toolbar button.

Procedure

First, make sure Point Measurement command.

  1. First, be sure the Drawing and Centroiding properties are set as desired. To open the Marker Properties dialog, click on the toolbar.

  2. If Marking Mode is not active, click the button on the window toolbar (not the Image Measurements Toolbar).

  3. Move the mouse pointer to each target point and click the left mouse button.

  4. Repeat for each target point on the image.

  5. To move an existing point, click on the Points toolbar to enter Move mode, then drag a marker to a new position and drop it there. To cause the centroids to be updated after the move, checkgenerate/checkbox.jpg Centroid after Move on the Centroid Properties (Markers) page:

  6. If points are no longer needed, click to enter Delete mode and click on the points to remove them.

  7. To track marked points through an image set, click on the toolbar. See the TIP below regarding tracking the centroid.

  8. To re-enter marking mode, click on the toolbar.

  9. To disable all toolbar modes for Point Measurements, click on the Image Bar or select Disable Modes from the Image Context Menu.

TIP

Before tracking through an image set, be sure generate/checkbox.jpg Track Centroid is set as desired on the Centroid Properties (Markers) page.

If checked, the centroid coordinates will be computed for every member of the image set.

If unchecked, the current coordinates will be duplicated to each member of the image set.

Measurement Results

Measurements are tabulated in the Points pane as shown above. Using this window, the measurements may be sorted, rearranged, saved to the clipboard or a file, etc.

If the image has a World Coordinate System ("WCS") calibration and the Centroid First Point box is checked in the Point Properties dialog , then (X,Y) is a centroid position computed from the centroid (column,row) position.

The items in the Report are described in the table below.

Point Measurements Column Data

#

The sequence number of the measurement.

Image

The name of the image that was measured

Distance

The distance in pixel units, or arcseconds if the image has a WCS calibration.

Index

By default, Mira fills this column with a sequential number which is the index of the point starting at 1. However, unlike the # column, which cannot be edited, this entry can be edited to give the point any identifier which then would be included in a saved or copied report.

X

The X coordinate of the point in world coordinates. If no world coordinate calibration exists, the value is the column position.

Y

The Y coordinate of the point in world coordinates. If no world coordinate calibration exists, the value is the row position..

Value

The value of the pixel at (X,Y).

Col

The column coordinate of the point.

Row

The row coordinate of the point.

Related Topics

Measuring Images

Distance & Angle Measurements

Plot Point Measurements

Measurement Panes

Image Windows

Pixel Coordinate Definition

Sub Pixel Coordinate Definition

World Coordinate System

 


Mira Pro x64 User's Guide, Copyright Ⓒ 2023 Mirametrics, Inc. All Rights Reserved.