Abstract

The number of polygons comprising interesting architectural models is many more than can be rendered at interactive frame rates. However, due to occlusion by opaque surfaces (e.g., walls), only a small fraction of atypical model is visible from most viewpoints. We describe a method of visibility preprocessing that is efficient andeffective foraxis-aligned oril.ria / architectural m[}dels, A model is subdivided into rectangular cc//.$whose boundaries coincide with major opaque surfaces, Non-opaque p(~rtc~/.rare identified rm cell boundaries. and used to form ana~ju{~’n~y,q)f~/>//con nectingthe cells nfthesubdivisicm. Next. theccl/-r/~-cc/ / visibility is computed for each cell of the subdivisirrn, by linking pairs of cells between which unobstructed.si,q/~t/inr. ~exist. During an interactive ww/krhrm/,q/~phase, an observer with a known ~~sition and\it)M~~~)~t>mov esthrc>ughthe model. At each frame, the cell containingthe observer is identified, and the contents {]fp{>tentially visible cells areretrieved from storage. The set of potentially visible cells is further reduced by culling it against theobserver’s view cone, producing the ~)yt>-r~]-t(>// \ i,$ibi/ify, The contents of the remaining visible cells arc then sent to a graphics pipeline for hidden-surface removal and rendering, Tests onmoderatelyc mnplex 2-D and 3-D axial models reveal substantially reduced rendering loads,

Citations