| Since convenient 3D city modeling is fundamental to the application of virtual city planning, digital entertainment, and E-learning,etc. Construction of virtual city model has profound application background, however, the use of interactive modeling tools and commercial modeling software could be very inefficient. Nowadays, procedural techniques becomes a more popular way due to its low cost and fast modeling.Four components of virtual city modeling are road network, function division, buildings modeling, and buildings layout. Though there are several existing technologies have some nice moves on road network and buildings modeling, certain types of constraints are inevitably required to be put in by users, which results extra work. For most of existing city planning system, user interaction is very inconvenient and some even requires professionals. One important aim of this article is to exhibit a simple and intuitive way, for either input of constrains or modification of result. Moreover, buildings layout which is one crucial part of city planning, is seldom referred in current algorithms. We are introducing a strategy of buildings layout by refining, which means first arranging the blue prints by blocks then working on the details using mosaic technique on every single block, to make it more reasonable.Following aspects will be discussed in the paper. First construct the basic road network,mainly depends on tensor field designing, flow visualization and the strategy of roads construction; Second introduce the characteristic elements of a city, such as river,lake,park,etc, mainly depends on CAGD. In the end, we will discuss the strategy of buildings layout, mainly depends on mosaic technique. This paper develops a 3D virtual city generating system,based on MFC and Open-GL,using Visual Studio 2005.We implement graph control and interaction panel by MFC,and accomplish model transformation and rendering by OpenGL,implementing several functions such as tensor field designing,flow visualization,etc rapidly. |
