This work presents two fast and iterative methods that integrate segmentation by watershed and three-dimensional visualization, while the classical approach is to separate these two processes. The user-aided segmentation is based on iterative watershed, efficiently implemented using the Image Foresting Transform (IFT). The first proposed algorithm consists of extracting segmented structures' borders during the segmentation and updating them at each iteration. Structure visualization is achieved by border projection. The second algorithm updates the image directly from the changes of the segmented scene occured in each step. The two methods were implemented in C and tested with various Magnetic Resonance Images. The results are satisfactory as compared to the classical approaches. The incremental image algorithm is a little faster than the classical one while the incremental border algorithm, although a little slower in segmenting, allows a very fast rendering, very suitable for object manipulation. Thus, the proposed methods provide a good feedback to user. © 2004 IEEE. 130137Audigier, R., (2004) Segmentação e Visualização Tridimensional Interativa de Imagens de Ressonância Magnética, , Master thesis, Faculdade de Engenharia Elétrica e de Computação, Universidade Estadual de Campinas, Campinas (SP), Brazil, Feb. Supported by CAPESFalcão, F.B.A.X., The iterative image foresting transform and its application to user-steered 3d segmentation (2003) Proc. of SPIE on Medical Imaging 2003: Image Processing, 5032, pp. 1464-1475. , FebBergo, F., (2004) Segmentação Interativa de Volumes Baseada em Regiões, , Master thesis, Instituto de Computação - Universidade Estadual de Campinas, Campinas (SP), Brazil, FebBeucher, S., Lantuéjoul, C., Use of watersheds in contour detection (1979) International Workshop on Image Processing, Real-time Edge and Motion Detection/Estimation, , Rennes,FranceBeucher, S., Meyer, F., The morphological approach to segmentation: The watershed transform (1993) Mathematical Morphology in Image Processing, pp. 433-481. , E. R. Dougherty, editor, New York (NY), USA, Marcel Dekker, IncDa Cunha, B., (2001) Projeto de Operadores de Processamento de Imagens Usando a Transformada Imagem-floresta, , Master thesis, Instituto de Computação, Universidade Estadual de Campinas, Campinas (SP), BrazilDijkstra, E., A note on two problems in connexion with graphs (1959) Numerische Mathematik, 1, pp. 269-271Dougherty, E., Lotufo, R., (2003) Hands-on Morphological Image Processing, , SPIE-The International Society for Optical Engineering, Bellingham (Washington), USA, AugFalcão, A., Bergo, F., Interactive volume segmentation with differential image foresting transforms IEEE Trans. on Medical Imaging, , To appearFalcão, A., Costa, L., Da Cunha, B., Multiscale skeletons by image foresting transform and its applications to neuromorphometry (2002) Pattern Recognition, 35 (7), pp. 1569-1580Falcão, A., Da Cunha, B., Lotufo, R., Design of connected operators using the image foresting transform (2001) SPIE on Medical Imaging, 4322, pp. 468-479. , FebFalcão, A., Stolfi, J., Lotufo, R., The image foresting transform: Theory, algorithms, and applications (2004) IEEE Trans. on Pattern Analysis and Machine Intelligence, 26 (1), pp. 19-29. , JanLotufo, R., Falcão, A., The ordered queue and the optimality of the watershed approaches (2000) 5th International Symposium on Mathematical Morphology, pp. 341-350. , JuneLung, C., Ertl, T., Hierarchical volume analysis and visualization based on morphological operators (1998) Proc. of the IEEE Conference on Visualization '98, pp. 335-341. , Research Triangle Park (North Carolina), USA, OctMeyer, F., Beucher, S., Morphological segmentation (1990) Journal of Visual Communication and Image Processing, 1 (1), pp. 21-46Phong, B.T., Illumination for computer generated pictures (1975) Communications of the ACM, 18, pp. 311-317. , JuneTorres, R., Falcão, A., Costa, L., A graph-based approach for multiscale shape analysis (2004) Pattern Recognition, 37 (6), pp. 1163-1174. , June. To appearUdupa, J., Herman, G., (1991) 3D Imaging in Medicine, , CRC Press, Boca Raton (Florida), USAUdupa, J., Odhner, D., Shell rendering (1993) IEEE Computer Graphics and Applications, 13 (6), pp. 58-67