The Scatter Analysis controls are used to create a scatter plot within McIDAS-V. The scatter controls show three different panels:

Image 1: HYDRA Scatter Analysis Display

The plot on the first panel on the left represents the first field selected in the Field Selector, the panel in the middle represents the second field which is selected through the Field Selector window, and the panel on the right is the scatter analysis of the two fields. The first field selected is represented on the X-axis (abscissa) and the second field selected represents the Y-axis (ordinate). The X-axis is selected in the Field Selector - the channel selected in the lower right Channels tab will be used as the X-axis.

Regions can be subsetted in any of the three panels, and the equivalent points will also be selected in the other two panels. For example, if a box is drawn in panel 1, the same box will be drawn in panel 2, and the points in these boxes will be colored the same in panel 3, the scatter analysis. To draw a box, select a Box radio icon and a color and use Shift+left-click and drag to select a region. Any enclosed shape can be drawn by selecting the Curve radio button and a color and using left-click and drag in any panel to select a region. A user is allowed one box and one curve per color in the scatter analysis (panel 3), and one box and one curve for the images (panels 1 and 2). To remove a region that has been subsetted, double-click on the color of the region to remove next to the Box/Curve radio buttons.

• Color bar - Determines the enhancement and range used in the display. Right-click on the color bar below the images to open the Color Table Editor, change the range, select other color tables, etc.
• Box - Sets the drawing mode to box, allowing the user to use Shift+left-click+drag to draw a box in either of the images or the scatter analysis.
• Curve - Sets the drawing mode to box, allowing the user to use left-click+drag to draw a shape in either of the images or the scatter analysis.
• - Sets the color of the box/shape and asociated pixels in the images and scatter analysis.
• - Removes any boxes or shapes drawn in the images or scatter analysis.
• - Opens a Scatter Statistics window which shows statistical information about the pixels contained within the user-defined domains drawn in the images or scatter analysis.
• Background Color - Sets the background color of the scatter analysis. This defaults to black. When black is selected, the axes and points in the scatter analysis will be white. When white is selected, the background will be white, and the axes and points in the scatter analysis will be black.

Below is the Scatter Statistics window that appears when the button is clicked. This includes statistical information about the data as a whole, as well as the regions of the data that were subsetted with a box/curve. The values in the white columns are computed for the image as a whole, and the values in the colored columns are computed for the area of the respective box/curve.

Image 2: HYDRA Scatter Statistics Window

• Maximum - Lists the maximum numerical value of the field within the boundaries of the entire image or a subsetted region.
• Minimum - Lists the minimum numerical value of the field within the boundaries of the entire image or a subsetted region.
• Number of points - Lists the total number of points within the boundaries of the entire image or a subsetted region.
• Mean - Lists the mean numerical value of the field within the boundaries of the entire image or a subsetted region.
• Median - Lists the median numerical value of the field within the boundaries of the entire image or a subsetted region.
• Variance - Lists the variance of the field within the boundaries of the entire image or a subsetted region.
• Kurtosis - Lists the kurtosis value of the field within the boundaries of the entire image or a subsetted region.
• Std Dev - Lists the standard deviation of the field within the boundaries of the entire image or a subsetted region.
• Correlation - Lists the correlation between the numerical values of the two fields within the boundaries of the entire image or a subsetted region.
• Difference Maximum - Lists the maximum difference in the numerical values of the fields on a pixel-by-pixel basis.
• Difference Minimum - Lists the minimum difference in the numerical values of the fields on a pixel-by-pixel basis.
• Difference Mean - Lists the mean difference in the numerical values of the fields on a pixel-by-pixel basis.
• Area [km^2] - Lists the area, in square kilometers, of the subsetted regions.
• - Saves this statistical data as a Comma-Separated Values (CSV) file (*.csv).

All of the menu items seen utilizing this display are standard options that can be found in the Menus section of the Layer Controls page.