| Among various kinds of three-dimension(3D)display technologies,computer-generated holography is an ideal and flexible one.It makes the record of virtual objects and digital storage of holograms possible,however,huge computational load and the expression of diverse virtual object are still problems remained to be considered.Volume data contains the original data of the 3D data field and has rich information.This research explored methods to generate CGH that can represent various information of volume data.The specific work is listed as follows:Firstly,the conventional CGH generation methods of volume data are carried on the research,including the polygon-based method,the MIP-based method and the approximate volume rendering method.Analysis finds that the traditional hologram generation method has some shortcomings,such as long time consuming and single information.Secondly,the CGH generation method based on point sources for volume data is proposed.Ray-casting algorithm is used to filter the effective information of volume data and compute synthetic point sources.The complex amplitude information of all the synthetic point sources are superimposed on the hologram plane.The traditional CGH generation method mainly focuses on the surface information of the object.Contrastively,the proposed method can flexibly adjust the region of interest and viewing angle of the object,and realize the holographic reconstruction of the internal information of the object.Thirdly,the layer-based CGH generation algorithm for volume data is proposed.The volume data is sliced to layers to make the complex amplitude and depth information of each layer of the object matched.And the diffraction process is calculated by a fast convolution algorithm.Experimental results indicate that the method can solve the mismatch problem of the depth information for translucent objects,and the depth clues of volume data can be clearly reconstructed,which helps to intuitively perceive the spatial structure of volume data. |
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