Digimizer - my new measuring eng

Digimizer - my new measuring engine

by the Theodore Lunar Observatory 2006 July 16

Introduction

Here is one example of the Digimizer© measuring capability using one of my digital images from the total lunar eclipse of 2004 May 4. This has been pasted to a suitably larger scale dark image so that the center of the umbra best fit circle is well within the composite image.

Figure 1

Procedure

Step 1 : Calibrate the image of the eclipsed Moon by a best fit circle and straight calibrator line (both in blue) set to the semi-diameter of the Moon at mid-eclipse (0.275°) as shown in the box and the Measurements list.

Step 2 : Find the grey scale contours at the umbra edge using the magic wand tool set at a line separation of 2, in red.

Step 3 : Find the best fit circle and its center to this umbra edge, in green.

Step 4 : Measure the umbra radius and read the values in the provided  box or Measurements list as  the measured umbra semi-diameter (Fi) of 0.731°. This is just slightly smaller than the expected mid-eclipse value of Fi = 0.7627°.

Additional Attributes

Captured images of the eclipsed Moon can be acquired from my input cameras such as the Meade Lunar & Planetary Imager (LPI), Canon IXUS still digital camera and Panasonic NV-GS15 Digital Video camera.

The quality of the composite image is good if kept to its original size as captured by <Alt> < Prnt Scrn> to the clipboard.  The Digimizer format (*.dgz) is much stronger and clearer in colour than if converted to *.jpg or *.gif .

The web site for the Digimizer© software can be found at http://www.digimizer.com/

Produced by the Theodore Lunar Observatory Australia 2006 July 16

Two other pages are available showing other uses of Digimizer as well as a comparison with Image Analyst.