Conde Rodriguez, Francisco de AsisTorres Cantero, Juan Carlos2015-11-112015-11-1120011017-4656http://dx.doi.org/10.2312/egs.20011010The use of hyperpatches as a method for solid modelling has a problem: the validity of the model is not guaranteed. The problem of ensuring the validity of hyperpatch representations of solids is discussed in this work, and a validity condition for cubic uniform b-spline hyperpatches is presented. Our validity condition is based on comparisons among points, and it is robust and easy to implement.