Collaborative systems are well established solutions for sharing work among people. In computer graphics these workflows are still not well established, compared to what is done for text writing or software development. Usually artists work alone and share their final models by sending files. In this paper we present a system for collaborative 3D digital sculpting. In our prototype, multiple artists concurrently sculpt a polygonal mesh on their local machines by changing its vertex properties, such as positions and material BRDFs. Our system shares the artists' edits automatically and seamlessly merges these edits even when they happen on the same region of the surface. We propose a merge algorithm that is fast-enough for seamless collaboration, respects users' edits as much as possible, can support any sculpting operation, and works for both geometry and appearance modifications. Since in sculpting artists alternatively perform fine adjustments and large scale modifications, our algorithm is based on a multiresolution edit representation that handles concurrent overlapping edits at different scales. We tested our algorithm by modeling meshes collaboratively in different sculpting sessions and found that our algorithm outperforms prior works on collaborative mesh editing in all cases.

Current modeling packages have polished interfaces for editing polygonal meshes, where artists work individually on each mesh. A variety of recent cloud-based services have shown the benefits of editing documents in real-time collaboration with others. In this paper, we present a system for collaborative editing of low-polygonal and subdivision mesh models. We cast collaborative editing as a special instance of distributed version control. We support concurrent editing by robustly sharing and merging mesh version histories in real-time. We store and transmit mesh differences efficiently by encoding them as sequences of primitive editing operations. We enable collaboration by merging and detecting conflicts. We extend this model letting artists adapt others' editing histories by retargeting sequences of editing operations to new parts of the mesh with potentially different topology. We tested our algorithms by editing meshes with up to thousand edits, in collaborative editing sessions lasting a few hours, and by retargeting sequences of several hundred edits. We found the proposed system to be reliable, fast and scaling well with mesh complexity. We demonstrate that our merge algorithm is more robust than prior work. We further validated the proposed collaborative workflow with a user study where MeshHisto was consistently preferred over other alternatives for collaborative workflows.