Xie, Qi; Liu, Dayou; Yu, Qiangyuan; Chen, Juan Direction relations model between indeterminate regions. (Chinese. English summary) Zbl 1107.68506 J. Jilin Univ., Sci. 44, No. 5, 748-753 (2006). MSC: 68U05 Computer graphics; computational geometry (digital and algorithmic aspects) PDFBibTeX XMLCite \textit{Q. Xie} et al., J. Jilin Univ., Sci. 44, No. 5, 748--753 (2006; Zbl 1107.68506)