Erik Vidholm and Ingela Nystrom.
Haptic volume rendering based on gradient vector flow.
In Proceedings of Swedish symposium on image analysis (SSBA'05), pp. pp. 97--100, 2005.

Bibtex:

@InProceedings{ vidholm:2005:HVGF,
  Author = 	"Erik Vidholm and Ingela Nystrom",
  title = 	"Haptic volume rendering based on gradient vector
                  flow",
  booktitle = 	"Proceedings of Swedish symposium on image analysis
                  (SSBA'05)",
  pages = 	"pp. 97--100",
  year = 	"2005",
}