the term “ surface computer ” used within this specification is meant to include any computer that is built into a table such as any table computer with a touch screen surface as well as wall mounted computers with touch screen surfaces . the preferred embodiment of the invention is a system referred to hereafter as sandtable that includes a general purpose , multi - touch software application written to enhance group collaboration for various planning , gaming , and educational purposes . sandtable can implement a variety of computer generated scenarios across a distributed network allowing participants at different geographical location to collaboratively participate in and / or alter ( edit ) the scenario . for example , one computer generated scenario could map out geographic locations of federal express ( fedex ) centers , with units on the map that represent fedex vehicles or trucks . participants located at remote locations could then access the computer scenario to view a geographic representation of the fedex centers , trucks and real time data of parcels that are to be delivered . the remote participants could , with the use of sandtable , collaboratively interact to schedule trucks and other resources to be sure the packages are efficiently and timely delivered . in another example , the military could use sandtable software to play war games . again , a map can be displayed that shows the geographical locations of friendly and / or enemy units . units can be such items as troops , trucks , tanks and the like . game players could move units , add units they have permission to add and create events while the game is being played . players can create events including firing weapons , creating alliances , firing missiles , and the like within the collaborative war game computer generated scenario . some of the benefits of sandtable include shared visualization for planning enhances integration and improved coordination . enhanced face - to - face collaboration among users of sandtable sharing a surface computer and the like improves communication and team work . minimum user training enables rapid deployment . sandtable leverages commercial off - the - shelf technologies , reducing costs . fig1 illustrates a system 100 implemented with sandtable including some of the hardware and networking components of preferred embodiment . the system 100 includes an administrator cell 120 that includes a server controller 124 . the administrator cell 120 controls a database 122 . the database may be any suitable database such as microsoft &# 39 ; s sharepoint 2010 database , for example . the administrator cell 120 uses the sandtable software as well as the backend database to create game scenarios for the end users . the administration cell 120 can also include a laptop 126 to provide an additional way of administering the system 100 as well as other monitors 128 for monitoring the system 100 . the system 100 includes two or more sites 1 - 4 . the sites 1 - 4 are client cells wherein the participants collaboratively participate in the computer . participants at each side can access the sandtable software through surface computers 102 by using multi - touch commands , laptop computers 104 or interact with a scenario other ways as understood by those of ordinary skill in the art . one or more of the different sites 104 can be networked together through a server 106 or router that connects them to the server controller 124 of the administrator cell 120 . participants or other observers can monitor the scenario on other monitors 108 connected to the server 106 . of course , those with ordinary skill in the art will appreciate that collaborative computing using sandtable software can be implemented in other networks , network configurations , and other hardware than what is shown in fig1 . fig2 illustrates the two primary modes that the sandtable software 200 operates in and how it interacts with other standard software . in the preferred embodiment , the sandtable software 200 can operate either in “ content explorer mode ” 202 or in “ scenario mode ” 204 . content explorer mode and scenario mode are descript names of what mode the sandtable software 200 is operating in . for example , in the fedex example discussed above scenario mode 204 may be more accurately referred to as “ map mode ” because maps may be of primary interest and in the war game scenario discussed above scenario mode 204 may be more accurately referred to as “ game mode ”. content explorer mode 202 dynamically loads file contents from a collaborative software such as sharepoint to allow participants to view , edit , and highlight documents , videos and images . in content explorer mode 202 , administrative users can upload file contents to the sharepoint database via the server or client laptops . the scenario mode 204 is used to dynamically create a specific scenario . scenario mode 204 allows users to browse the game scenario and add items to it . items include events , overlays , units , and inks . the user can update existing items , and / or move units based on their team credentials . units are items that are used to create actions and represent locations of organizations or facilities . as previously mentioned , units can be vehicles such as trucks in a fedex scenario or tanks , trucks , other military equipment and facilities when in a war game type of scenario . events are dialogue boxes on the screen that describe what is happening in a scenario . for example , dialog boxes can describe what is happening to a unit or describe an event in more detail . overlays are used to enhance game description by adding images on top of the scenario . for example , in a fedex or war game type of environment , specific maps can be overlaid on images of the scenario to precisely identify geographic features or unit locations within the maps . specifically , while in the scenario mode 204 , the sandtable software can interact with software to access advanced mapping capabilities so that accurate and detail map overlays can be added to a computer generated scenario . for example , infostrat inc .&# 39 ; s ve map control open source software can be accessed to implement mapping functions . both microsoft surface sdk 206 and infostrat ve map control 208 are their own independent frameworks that are separate from bae system inc .&# 39 ; s sandtable source code . the microsoft and infostrat source codes do not need to be modified to work with sandtable software . as shown in fig2 , while in content explorer mode 202 or scenario mode 204 , the sandtable software in the preferred embodiment can interact with a software developers kit ( sdk ) to develop multi - touch commands for the surface computers 102 of fig1 . for example , microsoft surface sdk v1 . 0 may be use or another sdc can be used . also , as discussed further below , the scenario mode 204 also provides functionality such as user team authentication and team item filtering . users can interact with and modify the game scenario and items when they present the correct credentials to the sandtable . fig3 illustrates some examples of the ways a participant can interact with sandtable through a surface computer 102 in content explorer mode 202 . a participant can explore and open a document by sliding two fingers apart as shown by arrows a , b . a participant can edit a content explorer item by inking with his finger 302 . inking is similar to drawing with a finger and is discussed later . inking can be thought of as collaborative white board functionality . a participant can highlight 304 content explorer item text with his finger . a participant can browse content explorer items from the content explorer bucket 306 . fig4 illustrates some of the graphic components and interactive devices use in interaction mode 204 to interact within a scenario . an event 402 is a dialog box that all participants can view and read , but only an administrative user may alter . an overlay 404 is an image that is attached onto the game scenario ( in this case a world map ). a unit 406 is created by users by clicking on add unit on the token ( the add unit symbol of a token is discussed below ). participants can also edit the type and details / actions of the unit 406 for their specific team . only administrative users can edit all the units . participants can sketch ink 408 on the scenario . a “ content mode ” button 410 allows a participant to return to content explorer mode 202 from scenario mode 204 . a “ minimize items ” bar 512 minimizes the items bar 414 while in scenario mode 204 . an items bar 514 allows quick access to events , overlays , units and inks . fig5 illustrates some of the uses of physical tokens 502 , 504 on a surface computer within a scenario . in general , a token is a chip that has a byte tag attached to its lower surface . sandtable interacts with physical tokens 502 , 504 to identify teams and authenticate different participants to filter scenario items . in the preferred embodiment , there are two types of physical tokens : user ( participant ) tokens and administrative tokens . there can be multiple user tokens 502 per computer scenario . the user tokens are used for filtering purposes and allow users to edit or add their own units 406 and inks 408 . in some scenarios , participants are only allowed to modify their own scenario items . in the preferred embodiment , there is only one administrative token 504 per scenario . the administrative token 504 allows the administrator to add events 402 and overlays 404 . the administrator is allowed to modify all scenario items , and is capable of viewing all items in a scenario . fig6 illustrates multiple participants accessing a scenario at a surface computer at the same time . as shown , multiple participants 602 may ink at the same time . the ink color is based on the token color next to the finger . if no token is present , a grey ink is used . participants can expand events 402 with finger touch . similarly , a unit 406 can be expanded with a finger touch . participants can edit the actions in the unit 406 . fig7 illustrates how participants can move units 406 by dragging them in the direction of arrow w and dropping them in the interactive scenario panel . fig8 illustrates how interactive mode 204 provides for advanced inking . in the preferred embodiment , two or more different participants may be inking on a scenario at the same time . the ink color is determined by the direction of a participant &# 39 ; s finger in relation to the token 502 , 504 next to him . in one configuration of the preferred embodiment , tokens 502 , 504 need be placed on the edges of the boarder 802 in order to work . tokens 502 , 504 are placed near the edges of the table . participants stand at the side of the table , facing the center of the table . the participant &# 39 ; s finger points forward ( within 45 degrees of true north , as shown by φ 1 and φ 2 ). the token location and finger angle determine the ink color to be used . example methods may be better appreciated with reference to flow diagrams . while for purposes of simplicity of explanation , the illustrated methodologies are shown and described as a series of blocks , it is to be appreciated that the methodologies are not limited by the order of the blocks , as some blocks can occur in different orders and / or concurrently with other blocks from that shown and described . moreover , less than all the illustrated blocks may be required to implement an example methodology . blocks may be combined or separated into multiple components . furthermore , additional and / or alternative methodologies can employ additional , not illustrated blocks . fig9 illustrates a method 900 of collaborative computing . the method 900 may be used in the fedex type of scenario ( environment ) discussed above , a war game scenario , or another type of scenario . the method 900 begins by simultaneously displaying a computer generated scenario , at 902 , including a plurality of items on a first surface computer and a second surface computer at a location remote to the first surface computer . the first surface computer and the second surface computer have interactive touch - sensitive screens that may be multi - touch sensitive . a first physical token placed on the first surface computer by a first person is identified , at 904 . the first physical token at least in part identifies credentials of the first person . the first person is authenticated , at 906 , based , at least in part , on the credentials of the first person to determine an authorization of the first person . the first person is allowed to edit items , at 908 , as permitted by the authorization of the first person . similar to the first token , a second physical that has been token placed on the second surface computer by a second person is identified , at 910 . the second physical token at least in part identifies credentials of the second person . the second person is authenticated , at 912 , based , at least in part , on the credentials of the second person to determine an authorization of the second person that is different than the authorization of the first person . the second person is allowed to edit one or more items , at 914 , as permitted by the authorization of the second person . the authorization of the second person permits the second person to edit at least one item that the authorization of the first person does not permit the first person to edit . in the foregoing description , certain terms have been used for brevity , clearness , and understanding . no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed . therefore , the invention is not limited to the specific details , the representative embodiments , and illustrative examples shown and described . thus , this application is intended to embrace alterations , modifications , and variations that fall within the scope of the appended claims . moreover , the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described . references to “ the preferred embodiment ”, “ an embodiment ”, “ one example ”, “ an example ”, and so on , indicate that the embodiment ( s ) or example ( s ) so described may include a particular feature , structure , characteristic , property , element , or limitation , but that not every embodiment or example necessarily includes that particular feature , structure , characteristic , property , element or limitation . furthermore , repeated use of the phrase “ in the preferred embodiment ” does not necessarily refer to the same embodiment , though it may .