--- title: "Collision Background" canonical: "https://documentation.chaos.com/space/ANIMA/124487849/Collision%20Background" format: markdown --- ## **Overview** --- Before you start your animation project, you need to prepare your 3D architectural models for using them comfortably in Anima. The imported 3D models will only be used as a reference for the design of the animation paths and areas, they won’t be visible during the rendering phase. Therefore, if your background model is very high-poly you may only want to bring the geometry essential for planning your animation into Anima. > ℹ️ A very dense geometry (like **trees** or other **highly detailed objects**) will have a **huge impact in the performance of the 3D viewport** of Anima, so we encourage you to only bring them if they are essential and, even then, you should consider make a** low-poly version** of them and bring that into Anima instead. So, the most important question you need to ask yourself before importing a model into Anima is: ### What do I need to populate the scene? Every project is different, but to help you decide what you need to bring into Anima, it is helpful to think about the elements of your scene as fitting into two different categories. #### Walking Surfaces These are all the surfaces on which characters will walk, climb, stand, or run, such as floors, stairs, terrains, and ramps. These surfaces are crucial to aid you in the design and placement of ***Paths*** and ***Areas***. #### Blocking Surfaces These are all the surfaces that can potentially block the actors on a path. They could be ***walls***, ***facades***, ***furniture***, or any other similar type of obstacles in your scene. Importing these will help you to design the ***Paths***, place ***Areas***, and create ***Avoiding Areas*** so that characters interact with the architecture of your scene convincingly. Anything that doesn’t fit into these categories does not need to be imported. > ℹ️ Each scene can contain **ONE** collision background. ## **Workflows** --- ### Creating a Background Model Using **Alive Synchronization** The best way to bring your ***collision backgrounds**** *to Anima is using the[ ](https://docs-chaos.atlassian.net/wiki/spaces/ANIMA/pages/124355890)**[Alive](https://docs-chaos.atlassian.net/wiki/spaces/ANIMA/pages/124355890)**[ connection](https://docs-chaos.atlassian.net/wiki/spaces/ANIMA/pages/124355890) to send a list of 3D objects directly from your 3D application, using the Anima plugins. That is the easiest, quickest, and more efficient way to get your 3D geometries and start creating your simulations. So, before continuing with this article and learning the manual way of doing it, make sure to take a look at the workflow with **Alive** in the following article [Anima Alive](https://docs-chaos.atlassian.net/wiki/spaces/ANIMA/pages/124355890). In some situations, it is not possible to use **Alive.** For example, if your **3D application is not supported** by our plugins yet (like it happens with Blender, Houdini, or Unity). In those cases, using an **external file** is how you can bring your 3D environment into Anima. ### Creating a Background Model Using a Standard 3d File --- --- --- --- ## **Hiding and Deleting Background Models** --- --- ## **Clip the Background Model** --- --- ---