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How To View an RTI File

Activating the PTM Viewer

This website includes nearly 400 interactive Reflectance Transformation Imaging-RTI (or Polynomial Texture Mapping-PTM) files, so it is important to understand how to open and use the files.

Screen Shot of Squeeze 
				Thumbnail and Caption

This is a screenshot showing the thumbnails of the squeezes and captions.

To access the interactive browser for the image file, click on the thumbnail of the squeeze. To be redirected to the catalog information about a particular squeeze, click on the text below the thumbnail.

Screenshot of JavaApplet

Screenshot of JavaApplet.

It may take several seconds for the browser to load, but once you have clicked on the thumbnail of the squeeze two Java Applet windows will appear on your screen, as shown above. One window (the left window) contains an image of the squeeze, while the other (the right window) includes sliders with titles like "light," "kSpec," "dGain," etc.


To manipulate the lighting of the squeeze, click and drag the mouse moving over the window with the image of the squeeze. As you move the mouse (while clicking and dragging) from top to bottom, left to right, or just circling the mouse over the image, you are manipulating the direction of the light and changing the effect of the light on the image. The position of the mouse represents the general direction of the lighting. For example if you click and hold the mouse on the far left of the image, the lighting will be coming from the left with dramatic shadows creating a raking light effect. You can change the intensity of the light by moving the slider titled "light" in the right window.


If you right-click the mouse over the image, you are given a dropdown list and can choose "effects" or rendering modes. The browser can apply mathematical transformations using surface shape and color information resulting in reflectance enhancements of various kinds. The "Specular" effect influences the reflectivity and diffusivity of an object's surface enhancing the perception of the surface shape.

The "kSpec" slider adjusts the percentage of specular reflection, derived from the surface shape of the subject and its reflection of light from any given direction. The "kDiff" slider adjusts the percentage of diffuse RGB color information used in the rendering. By moving this slider you can remove color from the image.

"Diffuse Gain" is a mode that increases the contrast, enhancing the perception of the surface shape. This mode has the potential of introducing false color in some situations. To increase and decrease the enhancement of this mode, move the slider "dGain."

Click here to see movie on PTM Viewer

Click on the screenshot above to see a movie walking through using the PTM Viewer.

The files included in this website are downsized greatly to ensure functionality online. Higher resolution files that show greater detail exist.


The Java Applets work best in Firefox and Safari. The Java Applets can take time to activate after clicking the thumbnail. This time is dependent on your internet connection.

If the viewer does not appear after clicking on a thumbnail image:

  1. Verify that you have the Java Run-time Environment(JRE) installed.
  2. Try quitting and restarting your browser.
  3. Try updating to the latest version of the Java Runtime Environment from Java.com.