Temenoujka Bandrova



                      Department of Photogrammetry and Cartography, University of ACEG

                                              Sofia, Bulgaria

                                     e-mail: bandrova_fgs@uacg.acad.bg



                                 2D or 3D modeling in cartography?

*      Recently cartographers used different graphical methods for representation of 3D spatial
objects and phenomena



*    The 2D maps are very comfortable for communication, distribution and usage.



*    The problem in 3D map is their perspective view, which changes from the position of the viewer.
Furthermore the perspective projection cannot be use for measure analyses. This means that they
cannot be used in paper version or other plane representation.

                                  Purpose of 3D symbols' research

            Formalization of the logic for cartographic representation of information in 3D maps
                                      applying a symbol system



*      rules for creation of a quality symbol system;

*      economically effective norms for working with 3D maps by various users.

    Investigation among 15 Bulgarian firms, working in the field of GIS, geodesy and cartography

*      6% - there is no need of symbols

*      94% - cartographic symbols are an important issue:

  --- geodetic network;

  --- thematic contents;

  --- pipe lines;

  --- traffic and public signs and marks;

  --- information signs and marks and others.

                                        3D MAP - DEFINITION



   Digital, mathematical defined, three-dimensional virtual representation of the Earth surface,
objects and phenomena in nature and society.



   Represented objects and phenomena are classified, designed and visualised according to a
particular purpose.



                                      Shortcomings of 3D Maps

*      The requirements of different hardware parts of computer are still high.

*      A lot of additional preparation is necessary  when different objects, phenomena and symbols
should be designed.

*      A strict control should be done in mutually situation of symbols and objects in animation 3D
maps.

*      There is not formally  defined 3D symbol system.

                              Steps for Creating of Symbol for 3D Map





                                       2D Symbols in 3D Maps

                                             billboard

*      Easy way for symbol creation



*      Geometry of rectangle + photo-texture of typical object



*      It is visible from many viewer positions excluding "top" and "bottom"



*      High photo-realism, fast and cheap way for symbol's creation of complex objects

                                                                              Subobjects in a symbol

*      Objects and subobjects in symbol creation



*      Subobjects -- 3D or 2D shapes

*      2D example: pedestrian path is a subobject in road



                                  Basic Requirements for Creating
                                             3D Symbols

*      The symbols should be similar to the real objects, which are represented in 3D map.

                                  Basic Requirements for Creating
                                             3D Symbols

*      Minimum polygons should be used when a new symbol is built

                                  Basic Requirements for Creating
                                             3D Symbols

*      The symbols should be created in their real dimensions.

                                  Basic Requirements for Creating
                                             3D Symbols

*      The symbols are designed for different purposes depending on user's needs.





















                                          Volumetric scale

                                            Plane scale

          The Designed and Created Symbols are a Part of Symbol System for 3D Map Because

*      They are built and systematized in syntactical aspect, spatial combinations between them are
available. 

                                         Levels of Details



                 An usage of  VRML as a Standart for Symbol Vizualizing in Internet











                         Parameters define optic characteristic of colours