This causes the 2D map to get stretched out. You can try it in the Sandcastle Camera example by commenting out everything in `reset` after `enableInput` and at the bottom, add:
```
var transitioner = new Cesium.SceneTransitioner(widget.scene);
transitioner.to2D();
```
You should set the frustum like before:
```
frustum.right = right;
frustum.left = -right;
frustum.top = top;
frustum.bottom = -top;
```
If you want to know more about orthographic or perspective projections, let me know.