Using Texture Mapping and WYSIWYG Painting to Create Geometric Tools *

The process of modeling geometric objects often entails modifica­ tion of a portion of a surface--a subsurface-which is part of a larger geometric shape. Most geometric modeling applications do not pro­ vide an interface that allows for user specification of arbitrarily shaped subsurfaces. We have developed two polygonal modeling applications which overcome this limitation. They employ an interaction technique based on 3D WYSIWYG painting which allows fine control over the precise shape of a subsurface; the painted region determines the sub­ surface that is to undergo geometric alteration. This correspondence between painting and geometric properties constitutes the basis of our modeling systems. And, while we operate on polygonal models exclu­ sively, we believe the technique may be generalized to higher-level models. Furthermore, this new type of modeling system has unexpected benefits. For instance, modeling often necessitates some form of refine­ ment prior to geometric alteration. Our modeling systems accomplish this by using a variety of common image processing algorithms applied to texture maps which are created as a bi-product of 3D WYSIWYG painting. Also, our established correspondence between paint and ge­ ometry, enables us to create new modeling paradigms by associating painting properties with geometric properties. Finally, we offer a range of applications that can benefit from such a technique. CR Categories: 1.3.5 [Computer Graphics]: Geometric Transfor­ mations and Object Modeling 1.3.6 [Computer Graphics]: Interaction Techniques 1.3.7 [Computer Graphics]: Texture Additional