Creating Tagged Objects
In addition to fingers and blobs, the Microsoft Surface Vision System can recognize special tagged objects that are marked with byte tags or identity tags.
Every Microsoft Surface developer unit includes two full sets of byte tags (256 tags in each set). You can order more byte tags, but you can also create your own. (For more information about how to order byte tags, see How do I order more byte tags?.)
|You can also create and print your own identity tags by using the identity tag printing tool that is included in the Microsoft Surface SDK.|
Tag Printing Resources
The Microsoft Surface Byte Tags download includes several resources to help you print more byte tags:
A Microsoft Office Visio document that has labels on the tags for easier identification and a cleaner layout. These tags are suited for printing because the Visio document ensures the correct dimensions when you print them.
A ZIP file that has all 256 byte tags as PNG files at 300 dpi resolution, in case you need to print tags.
An HTML version of the Visio document for easy reference in case you do not have Microsoft Office Visio on your computer. Do not use this document for printing tags because you cannot make sure that your Internet browser is printing them at the correct size.
A PDF document that has all 256 byte tags, for easy portability of a full set of tags.
Printer Requirements for Creating Tagged Objects
For any tags that you print and that you plan to use in a venue, we recommend that you have them professionally printed and that the printer adheres to the following specifications:
The Microsoft Surface Vision System sees infrared (IR) light at 850 nanometers (nm). The light reflectance properties of materials in the visible spectrum (Human Vision System) can be very different at 850 nm.
Byte tags must have the correct dimensions for the white dots with a minimum dark region of 0.75 inches wide by 0.75 inches high. In some situations, where the tag is positioned on a very highly reflective surrounding background, you might need to increase the size of the dark region to 1 inch or more to improve tag recognition. Also, make sure to prevent unintended scaling of the white dots in your workflow from design to final output.
The white dots must reflect at least 73% of 850 nm infrared light but not more than 86%. Ultra high reflectivity whites can cause "bloom," which impairs the vision system's ability to recognize the tag.
The dark region must not reflect any more than 7% of 850 nm infrared light (93% or more should be absorbed).
Note The infrared reflectivity of an object is not necessarily the same as its brightness to the naked eye. For example, some materials that appear dark to the eye can actually be reflective to infrared light.
Whenever possible, put tags on infrared-absorbent objects. A tag on an object that is infrared-absorbent typically performs better than a tag on a highly infrared-reflective item. If you place a tag on a highly infrared-reflective surface, the Microsoft Surface Vision System might have trouble recognizing the tag. A single tag on a physical object that has a black or non-IR reflective background provides the best tag recognition performance.
Place tags on a solid, consistent background that includes no patterns or stripes, for example. Use a light-colored background instead of a dark background. The byte tags that are included with a unit are thin to improve usability, but dark backgrounds adversely affect the contrast and readability of the tag.
Place tags on flat surfaces that help the tag maintain flush contact with the Microsoft Surface screen. Also, tags work better on physical objects that do not easily tip over when they move.
|You can use a reflectometer to accurately measure the reflectance properties, or you can use trial-and-error and test all final product output on Microsoft Surface before you move to a larger-scale production.|
Printing Your Own Tags
Ink jet printers that use a mix of cyan, yellow, and magenta to create black generally do not work. The three-color combination is typically invisible in the infrared spectrum. You should test all printing methods for their appearance in the infrared 850 nm wavelength.
Four-color printing processes do not typically work well. What appears black in the visible spectrum (human eye) might not be black at 850 nm. Some whites do not reflect enough light at 850 nm to appear white to Microsoft Surface. Monochrome laser printer output works very well, although without a laminate the tags do degrade fairly quickly due to the texture of the Microsoft Surface screen.
Be careful that the tags cannot be rubbed off. Tags that are printed by using ink jet or laser printers wear off quickly when they are used. If the tag printing wears off, you can no longer use the tag and the tag will smudge the Microsoft Surface screen. The tags that are included with the unit are printed on self-adhesive vinyl to protect them from wearing off.
Producing Transparent Optical Tags
In addition to standard byte and identity tags, you can create transparent optical tags that you can laminate to one side of a clear, adhesive sheet, which allows you to attach the tags to most hand-held objects.
For more information about how to create transparent optical tags, see Creating Transparent Optical Tags.