The first step in adding a 3D model to the game is creating or finding one to use. OOTP uses the Open Asset Import Library to import 3D models, which allows our modders to use a variety of different free and open model formats. It allows the game to import file formats like Collada (.dae), 3ds Max 3DS (.3ds), Wavefront Objects (.obj), and others. There are a variety of 3D model-sharing sites, notably 3D Warehouse. Searching for "baseball" or "ballpark" on those sites will show you dozens of great models that can be imported into OOTP, or edited to make changes and then imported. Please, however, respect the wishes of the original authors of the models regarding their use, and the terms of use of the model-sharing sites.

Many freely-available models are available in SketchUp (.skp) format. SketchUp is a very user-friendly program that's useful for getting started if you're new to 3D. However, OOTP can't import .skp files directly. They must first be opened in SketchUp, and then exported to either .obj file format (which requires SketchUp Pro, the paid version) or to .dae (Collada). The exported file can then be loaded into OOTP.

Unfortunately, due to the complexity of 3D modelling, we can only offer informal advice, not official support, on dealing with the modelling-related issues, including the results of the import process, which can vary widely depending on the file format and nature of the model. We've tested the Wavefront Object (.obj) format extensively, and it works well and loads quickly in OOTP, so that's likely the safest bet when importing stadiums. But you're welcome to try any other supported import format, and we'd be happy to hear your comments on format-specific issues on our forums.

While there are is a lot of good 3D modelling software available for free, such as SketchUp and Blender, it should be remembered that 3D is rather difficult and complex no matter which modelling software you're using. It may require some trial and error to get the best results - a model may look great in Sketchup, but after being exported in .obj format it may have bad textures and other issues. When that happened with one of our models, it turned out the simplest way to fix it was exporting and importing three times in the row - with every step, SketchUp fixed some of the problems. In the end the model was less complex (only a fifth of the initial file size) but still complete and free of errors.

If you want to create your own 3D models, it's a good idea to test them frequently in OOTP. It's easier to discover and deal with issues as they arise, rather than spending a vast amount of time building a complex model, and then having it import poorly. That leaves you with the task of diagnosing exactly what's wrong, which can be extremely frustrating if you don't know when and where the problems you're seeing arose. If you do run into problems, we suggest MeshLab as a useful tool for cleaning up your model.