Creating mr Proxy Objects

Now that the tree objects you need for your scene are set up, you can convert them to .mib format so they can be used as mr Proxy objects.

mr Proxies are useful when you want to fill a scene with instances of objects that have a high polygon count, such as 3D trees. Proxy objects save you time and free up memory because they do not need to be converted to mental ray format and their source objects do not need to be present during render time.

Save source objects in mr Proxy file format:

  1. On the Quick Access toolbar, click the Open File button, navigate to the \scenes\dynamics_and_effects\particle_trees folder, and open the scene ptrees.max, or continue working in your own scene from the previous lesson.

    You will now take the trees you created in this scene and save each one individually so they can be available for use in other projects.

  2. From the Create panel > Objects list, choose mental ray.

  3. On the Object Type rollout, click mr Proxy.

  4. Maximize the Perspective viewport if required, then click and drag anywhere in the scene.

    A proxy object is created.

  5. Go to the Modify panel and in the Parameters rollout > Source Object group, click the Source Object button (initially labeled “None”), then in the viewport, select the Elm-Winter object.

  6. In the Parameters rollout > Source Object group, click Write Object To File.

  7. On the Write mr Proxy File dialog > File Name box, type Elm-Winter and click Save.

    The object will be saved in .mib file format, a mental ray proxy file type, and placed by default in the current 3ds Max project renderassets folder.

  8. On the mr Proxy Creation dialog, click OK to accept the default values.

    If your tree object contained animation, you would use the mr Proxy Creation dialog to save the object as a sequence of frames, with an .mib file created for each frame. You specify the time segment to be saved in the mr Proxy Creation dialog > Geometry To Write group.

    After you save Elm-Winter, a thumbnail image of the file displays in the mrProxy Parameters rollout > Display group. The proxy displays in the viewport as a point cloud, a set of vertices showing the object size and approximate shape.

  9. In the Parameters rollout > Display group, set the Viewport Verts spinner to 512 and press Enter to increase the number of points in the point cloud.

    Left: Point cloud represented by 128 vertices

    Right: Point cloud represented by 512 vertices

    The object outline becomes more apparent as more points are displayed, but a denser point cloud can affect viewport performance.

  10. Set the Viewport verts spinner to 128 to return to the original setting, then turn on Show Bounding Box to display the extents of the tree proxy.

  11. With the proxy object selected, repeat steps 2 to 8 for the Elm-Spring tree object.

    When you’re done, you should have an .mib file for Elm-Spring. Ordinarily, you would repeat the steps for every tree in your scene, but to speed things up a little, .mib files have been created for all the tree types in the \sceneassets\renderassets folder. You will use these proxies in the next lesson.


Loading Proxy Files Into a Scene