Satellite Observations in Science Education

Feature Sizer


This RCO allows a user to estimate the area of a feature within an image. It has two modes. The first mode lets the user overlay and resize a geometric shape on top of the feature to measure the area. This mode lets the user obtain a rough estimate of the area. The second mode lets the user trace the outer border of the feature, and automatically calculate the area by clicking a button once an acceptable trace is complete. This mode gives a more precise measure of a feature's area.

The instructor will gather a set of images, and for each must determine the units per pixel, provided as an XML parameter, in order to correctly compute the area of the target feature. A contrast tool will allow the user to either stretch or compress the image contrast which may help the target feature stand out better.

The sample XML file provided below must be populated with appropriate data (filenames, ancillary information about the images, etc.) and placed in the same location as the HTML file used to access and present this RCO.

To implement placing and resizing geometric shapes, a portion of the Open Source Physics framework was adapted and bundled as a .jar file for use in the SOSE project. This .jar file comes bundled with the RCO automatically, no action is needed on your part.

Example usage:

This link will bring up a separate browser window with a page that uses this RCO.

Snapshot of sample use:

Example use of Feature Sizer RCO

How to use

  1. Create an HTML file which will reference and load this RCO. The template below can be used as a starting point.
  2. Create an XML file to initialize your RCO using one of the two methods below.
  3. Download the Feature Sizer RCO by right-clicking the download link below and choosing "Save Link Target As..."
  4. Edit the applet tag parameters to set the space used by the RCO, and to reference your file names. Now test!

Create your XML file one of two ways:

  Edit this sample Feature Sizer XML file

  Generate your XML automatically with this link.

Download this RCO here

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