The sculpture collection we have used at the Virtual hall project comes from Sketchfab. All of them have been modified and optimized by our team to ensure a fluent simulation and the best quality. We would like to mention the original authors according to the Creative Commom license that they use to share their models and thanks their generosity.
The sculptures come in a big variety of qualities, usually between 50 000 and 200 000 polygons. our Team have optimized them to 15 000 polygons the small models and 30 000 the big or complex ones. To do it the process have three phases: Correction of original models, Reparametrizations and polycount reduction, Detail textures baking.
The First phase, not always necessary, was eliminate the defects on the original models, cap the meshes as solid objects and ensure the texture properly cover all the model.
The Second process has been the reparametrization of the surface, to obtain simply and clean meshes. With this versións we have halved them six times the polycount. We have create a new Level Of Detail (LOD) in each step. These levels of details (LOD) allow the engine to change the model for one with less detail according the size on the screen, using a model simpler when we are far and one with many detail when we are close to the object. This way we can support many objects in the scene without overloading the GPU.
The last phase was create textures to recuperate the detail we have lost in the last process. We used Xnormal to generate by comparison between the roiginal model and our model a normal map for the fisrt LOD. As part of this process we also rebuild the object texture, It's needed after the reparametrization, where the original UV coordinates got lost.