author = "Pinto, Francisco de Moura and Freitas, Carla Maria Dal Sasso",
          affiliation = "UFRGS and UFRGS",
                title = "Two-Level Interaction Transfer Function Design Combining Boundary 
                         Emphasis, Manual Specification and Evolutive Generation",
            booktitle = "Proceedings...",
                 year = "2006",
               editor = "Oliveira Neto, Manuel Menezes de and Carceroni, Rodrigo Lima",
         organization = "Brazilian Symposium on Computer Graphics and Image Processing, 19. 
            publisher = "IEEE Computer Society",
              address = "Los Alamitos",
             keywords = "Volume visualization, transfer functions, volume rendering.",
             abstract = "Direct volume rendering plays an important role in the 
                         investigation of volumetric data. In order to display these data, 
                         their values must be associated to optical properties. This task 
                         is accomplished by transfer functions (TFs), which assign 
                         properties like color and opacity to voxel values in the volume. 
                         TFs are very important to produce informative images that reveal 
                         volume features, but their specification is a non-trivial and 
                         unintuitive problem. Without any help in the TF design process, 
                         the user goes through a frustrating and time-consuming 
                         trial-and-error process. This work proposes a two-level 
                         interactive framework combining a few useful semi-automatic design 
                         techniques for one-dimensional opacity and color transfer 
                         functions. We use the histogram approach proposed by Kindlmann and 
                         Durkin, manual design aided by dual domain interaction (space 
                         domain and TF domain), stochastic evolutive design and qualitative 
                         analysis of multiple TF possibilities using a Design 
                         Galleries-inspired method (thumbnails in the first level of 
                         interaction and refinement of zoomed-in images in the second 
                         level). The combination of these strategies offers precise control 
                         over the transfer function specification, plus some interactive 
                         guidance, as well as semi-automatic and evolutive search in the TF 
  conference-location = "Manaus",
      conference-year = "8-11 Oct. 2006",
             language = "en",
           targetfile = "pinto_transfer_functions.pdf",
        urlaccessdate = "2020, Nov. 26"