PTM Viewer Instructions
	This viewer allows you to display Polynomial Texture Maps (PTMs) using your Java-enabled web browser.
		PTMs dynamically display the way light illuminates objects. The information present in PTM images enables the PTM viewer to display the image using lighting models similar to those employed to illuminate virtual three dimensional objects. These models allow different properties of the illumination experience such as light direction, color, reflectivity, and the sharpness of highlights to be displayed together or separately. The models also permit mathematical enhancement of illumination properties which can disclose surface characteristics impossible to capture with the naked eye or standard photography.
	Viewer Operation
		When the viewer is started, a page will appear with one or two images of the desired content. If the images do not appear, you may not have an appropriate version of the Java Runtime Environment installed, or it may not be set up correctly. See the PTM Troubleshooting Page page for more information.
		To view a PTM, click on one of the images. It may take a few minutes to load depending on the speed of your connection, you should see a small window that says "loading PTM..."
		When the loading is complete, two windows will appear. The left window contains the PTM image and the right window contains parameter controls for the viewer's display and enhancement modalities.
		The viewer's display options are selected from a Java applet window activated by clicking the right mouse button. The direction from which the image is illuminated is determined by clicking and dragging the left mouse button.
	Display Options in the Java Applet Window
	Changing the Illumination Direction
	Clicking and dragging with left mouse button in the PTM Window controls the illumination direction. When the cursor is positioned in the center of the image and the left mouse button clicked and dragged slightly, the light is positioned at 'high noon', perpendicular to the image plane. By clicking and dragging the cursor in any direction from the image center towards the image edge, the illumination angle will approach the 'horizon', parallel to the image plane, in the direction that the cursor is dragged.
	Right Mouse Menu
	Clicking the right mouse button brings up a menu of illumination and enhancement effects.
		Effects
				Effects off: Turns off enhancement effects.The default viewing mode. Color and reflection properties are displayed without enhancement.
				Specular: Turns on enhancement of the reflective illumination properties. Displays the image content as if it was a highly reflective material.
				Diffuse Gain: Turns on enhancement of the color properties' tone value (light/dark) contrast.
				Display Normals: Turns on display of the image content's surface normals. Normals indicate the direction perpendicular to each point on the surface of a 3D object. PTMs capture this information from the image's content. This normal information gives PTMs their 3D qualities.
		Performance
				Detail: Displays all image information and is the default.
				Sampling: sub-samples the image, and scales it to full size. Increases the viewer's operating speed and smoothes 'stutter' during illumination direction transitions at the expense of image resolution.
				Interpolated Sampling: Uses bilinear interpolation to scale the image. Provides an intermediate speed increase and resolution reduction.
		Light Source
				Directional: Illumination as if from infinite distance, similar to sunlight. Light rays are parallel and strike the image evenly. The default.
				Local: Illumination, similar to a flashlight. The diameter of the light beam can be changed with a 'distance' slider which is activated below the 'light' parameter slider in the right window. A more expensive option.
		Default
				Default: Resets all menu settings
		Animate
				Animate: Check this Box to animate the illumination direction. Dragging the mouse suspends animation. Uncheck the box to stop the animation.
	Control Window
	By default, with no enhancement or lighting options, only the slider for "light" is active. The other sliders become active when their options are turned on.
		General
			Light: Controls the overall illumination intensity.
			Distance: If the "local" light source option is selected, this slider is activated. 'Distance' controls the diameter of the brightly illuminated image area by changing distance of the virtual light from the image.
		Specular
			kSpec is the intensity of reflection properties in the image and effects image brightness.
			kDiff is the intensity of color properties in the image and effects image brightness.
			exp is the highlight size (low value = spread out, high = smaller and sharper).
		Diffuse Gain
			dGain slider controls the intensity of the image color properties' tone value (light/dark) contrast.
	PTM Technology was developed at HP Labs: hpl.hp.com (...)
	The Applet PTM viewer was created by Cliff Lyon who has generously allowed CHI to use it. For more info about the viewer click here: materialobjects.com/ptm/
	If you can't see the viewer or no images appear, click here: PTM Troubleshooting Page
	If you have trouble viewing PTMs in your web browser, you can try using the free standalone PTM viewer from HP. After it has been installed on your computer you can download and view CHI PTM examples. Download PTM Examples.