[Source] Xj3D property setting for origin manager, for inclusion in X3D-Edit

[Don Brutzman]

Rex Melton wrote:
> 
> Hi Don,
> 
> Attached are the preliminary release/implementation notes, including
> descriptions of the applicable properties.

thanks Rex, i think X3D-Edit is set up correctly.

wondering did your change documentation make it into the release?
didn't see it.

> Don Brutzman wrote:
>  > Terry, Alan reports that the Xj3D command line switch for geo origin
>  > manager
>  > is enableOriginManager.  I believe that you have already compiled his
>  > new code successfully in your Wednesday X3D-Edit build.
>  >
>  > Rex, is there an Xj3D browser property we might set for embedded use of
>  > Xj3D in X3D-Edit?  Also, is there a documentation page for use of the
>  > Browser properties we might check to ensure we are doing things
>  > correctly?
>  >
>  > if we have this by Monday we can likely ship the update on the Showcase
>  > DVD version.  TIA for all help.
>  >
>  > all the best, Don
> 
> 
> ------------------------------------------------------------------------
> 
> 
> Description
> 
> The dynamic origin management strategy currently implemented in Xj3D is 
> an extension to the original implementation. Internal to the browser, 
> all geo-referenced coordinates are converted into GCC (Geocentric 
> Cartesian) for use in rendering and transformation. The original 
> implementation would offset those coordinates by the GeoOrigin position 
> as nodes were instantiated. The functional addition to the browser 
> consists of a manager class that makes determinations based on the 
> user's Viewpoint on when and where a new local origin is required, and 
> notifies the loaded Geo nodes that they must update their interal state 
> to account for the new setting.
> 
> Local origins will be configured at either the ellipsoid center, or at 
> the ellipsoid surface. The default origin manager's criteria for 
> switching the local origin setting are configured with two parameters. 
> An elevation above the ellipsoid is used as a threshold for establishing 
> an initial local origin. A Viewpoint elevation above the threshold will 
> cause the local origin to be configured as at the ellipsoid center. An 
> elevation below the threshold will cause a local origin to be configured 
> at the Viewpoint's geodetic position on surface of the ellipsoid. Once a 
> local origin has been established at the ellipsoid surface, an 
> orthodromic distance from that local origin will be used as a threshold 
> for reconfiguration. When the Viewpoint moves beyond the threshold 
> distance from the local origin a new origin is established, again at the 
> Viewpoint's geodetic position on surface of the ellipsoid.
> 
> Implementation Notes
> 
> The dynamic origin management may be configured with properties.
> 
>     * "org.xj3d.core.eventmodel.OriginManager.enabled": A boolean. true
>       enables the dynamic origin management. Any other value disables
>       dynamic origin management and the GeoOrigin node will be used to
>       configure the local origin.
>     * "org.xj3d.impl.core.eventmodel.DefaultOriginManager.elevation_threshold":
>       A double. Establishes the elevation threshold in meters. Defaults
>       to 50000.
>     * "org.xj3d.impl.core.eventmodel.DefaultOriginManager.distance_threshold":
>       A double. Establishes the distance threshold in meters. Defaults
>       to 50000.
> 
> Implementation Caveats and Issues
> 
>     * There may be multiple browser instances with independently
>       configured OriginManagers, provided that the Geo nodes are not
>       grouped in Protos. If Geo nodes are grouped in Protos, then only a
>       single Browser instance is allowed.
>     * Within a browser instance, the Geo nodes must be in a single,
>       unshared layer - specifically layer 0.
>     * Navigation: In Track navigation mode, when the centerOfRotation is
>       set from user input - and the origin changes as a result of the
>       automatic 'zoom in' to the new  center, the navigation processor
>       incorrectly adjusts the user position.

all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br           brutzman at nps.edu
Watkins 270   MOVES Institute, Monterey CA 93943-5000 USA  work +1.831.656.2149
X3D, virtual worlds, underwater robots, XMSF  http://web.nps.navy.mil/~brutzman