Image SXM

Creates a 3d plot of the surface, allowing the user to specify the direction from which the surface is viewed. The colours used for each pixel in the 3d plot can be taken from (i) the original image LUT; (ii) a calculation of the illumination of the surface from a light source in a specified direction; or (iii) a mixture of the previous two options. Press the option key to bypass the dialog box.

The view, light and z scale parameters can be changed using the cursor keys and the option, control and shift keys, respectively. The view and light angles can also be changed by dragging the small circles of the geometry icon (in the top right of the plot window). Clicking in the square resets all the view, light and z scale parameters to their initial values. Option-clicking in the square resets the parameters to their default values. The view angle of a 3d plot can also be changed by holding down the space bar and dragging the mouse around in the plot window.

The 'High Quality/Slow Speed' option enlarges the image, makes a 3d plot, smooths the plot and then reduces the size of the plot window slightly. The result is a higher quality 3d plot, but it takes about 4 times longer to draw and requires more free memory. Unlike for the 'Low/Fast' option, the geometry of 3d plots created using the 'High/Slow' option cannot be altered using the cursor keys. I would suggest that the 'High/Slow' option is used only when you are sure of the view/light/z scale settings.

The 2d plot option, producing a conventional flat image, may be useful for mixing the image colours with shadows to obtain a better impression of the surface topography. The 4d plot option creates a 3d plot of an image with the colours of each pixel in the image tinted according to whether or not the corresponding pixel of a second image (which is assumed to have been density sliced previously) lies between the slice limits set.