Outline: Software Design Goals History of software design ideas Design principles Design methods Life belt or leg iron?(Budgen)

design: added inheritance, multiple inheritance, and polymorphism to ADT In process added complexity and increased some types of connectivity Lots of claimed advantages -- so far empirical evaluation is not supporting them well

Abstract Model Specifications Build an abstract model of required software behavior using mathematically defined(perhaps using axioms )types(e. g sets, relations) Define operations by showing effects of that operation on the model Specification includes Model

Requirements specification: A structured document that sets out the services the system is expected to provide Should be precise so that it can act as a contract between the system procurer and software developer and thus needs to be understandable by procurers and developers

Evolutionary Model Prototyping- \Do it twice to assess feasibility to verify requirements May only be a front end or executable specification Or develop system with less functionality or quality attributes °3 approaches:

Too complex for complete analysis Separation into non-interacting subsystems distorts the results The most important properties are emergent Too organized for statistics Too much underlying structure that distorts the statistics Organized Complexity\(Weinberg) Copyright Nancy Leveson, Sept 1999

Is there a problem? Why Hard? Syllabus EXamples AAS(FAA Advanced Automation System) FBI CIC IRS Modernization Program

以往视觉方法特点: 作为主体的视觉系统被动地接收外界的信息 处理过程复杂、难以实现而且没有充分考虑生物视觉的特点 以往视觉方法忽略的问题: 中央凹(Fovea)的高分辨能力和视网膜上其它部分(不妨称之为外围视觉)的相对较低的分辨能力之间的差异

6.1运动场(Velocity)与光流(Optical Flow) 一运动场 物体与摄象机之间的任何相对运动都将导致视平面上与空间物体对应点发生变化。严格地说空 间运动在视平面上引起的对应运动称为运动场,如图6.1所示。假定空间点P与摄象机之间相 对运动的速度为V,在视平面上对应点的运动速度为v,则 VdR

5.1从阴影恢复三维形状 5.1.1成像过程的数学模型 一、图象辐照度的形成