Systems and mehtods for annotating pages of a 3d electronic document

Abstract

To annotate a three-dimensional electronic document, a user specifies, on a two-dimensional screen, a portion of a page of a three-dimensional document as a specified page area to be annotated by making a stroke. The annotation may be displayed to the user by a hybrid technique where the annotation is displayed by a 3D polyline segment placed behind the near clipping plane of a virtual camera frustum. At the same time, previous annotations are displayed by another technique, such as, for example, the texture coloring technique. During the intermittent time between the stroke and another stroke the 3D polyline segment is removed from behind the near clipping plane and the page texture is updated with the annotation data. The display techniques support highlighting annotations, free-form annotations, and text annotations.

1 . A method for annotating a three-dimensional page of a three-dimensional electronic document, comprising:
 displaying the three-dimensional page of the electronic document;   receiving, via an annotation tool, an indication of an area of the three-dimensional page to be annotated;   annotating a layer corresponding to the three-dimensional page, by marking the area of the three-dimensional page specified by the annotation tool, the layer being represented by a three-dimensional geometry; and   displaying an annotation corresponding to the specified area, wherein the annotation is displayed in a layer formed behind a near clipping plane of a virtual camera frustum.   
     
     
         2 . The method of  claim 1 , wherein specifying the area of the three-dimensional page to be annotated includes:
 determining coordinates of the specified area on a two-dimensional screen in a screen coordinate system; and   mapping the coordinates of the specified area from the screen coordinate system to the layer.   
     
     
         3 . The method of  claim 1 , further comprising transforming annotation on the near clipping plane onto a second layer near a representation of the three dimensional page. 
     
     
         4 . The method of  claim 1 , wherein the annotation of the layer corresponding to the three-dimensional page uses a raycasting technique. 
     
     
         5 . The method of  claim 1 , wherein the layer displayed behind a near clipping plane of a virtual camera frustum avoids a Z fighting problem. 
     
     
         6 . A computer readable storage medium on which is recorded a set of instructions for performing functions when executed by a controller, the functions comprising:
 displaying a three-dimensional page of an electronic document;   receiving, via an annotation tool, an indication of an area of the three-dimensional page to be annotated;   annotating a layer corresponding to the three-dimensional page, by marking the area of the three-dimensional page specified by the annotation tool;   displaying an annotation corresponding to the specified area, wherein the annotation is displayed in a layer formed behind a near clipping plane of a virtual camera frustum.   
     
     
         7 . The computer readable storage medium of  claim 6 , wherein the function of specifying the area of the three-dimensional page to be annotated includes:
 determining coordinates of the specified area on a two-dimensional screen in a screen coordinate system; and   mapping the coordinates of the specified area from the screen coordinate system to the layer.   
     
     
         8 . The computer readable storage medium of  claim 6 , the functions further comprising instructions for transforming the annotation on the near clipping plane onto a second layer near a representation of the three dimensional page. 
     
     
         9 . The computer readable storage medium of  claim 6 , wherein the function of annotating the layer corresponding to the three-dimensional page uses a raycasting technique. 
     
     
         10 . The computer readable storage medium of  claim 6 , wherein the layer displayed behind the near clipping plane of the virtual camera frustum avoids a Z fighting problem. 
     
     
         11 . An apparatus for annotating a three-dimensional page of an electronic document, comprising:
 a display;   an annotation tool; and   a controller that controls display of the three-dimensional page of the electronic document, receives, via the annotation tool, an indication of an area of the three-dimensional page to be annotated, to annotate a layer corresponding to the three-dimensional page, by marking the area of the three-dimensional page specified by the annotation tool, and displays an annotation corresponding to the specified area, wherein the annotation is displayed in a layer formed behind a near clipping plane of a virtual camera frustum.   
     
     
         12 . The apparatus of  claim 11 , wherein the controller determines coordinates of the specified area on a two-dimensional screen in a screen coordinate system, and maps the coordinates of the specified area from the screen coordinate system to the layer. 
     
     
         13 . The apparatus of  claim 11 , wherein the controller further transforms the annotation on the near clipping plane onto a second layer near a representation of the three dimensional page. 
     
     
         14 . The apparatus of  claim 11 , wherein the controller annotates the layer corresponding to the three-dimensional page using a raycasting technique. 
     
     
         15 . The apparatus of  claim 11 , wherein the layer displayed behind the near clipping plane of the virtual camera frustum avoids a Z fighting problem.