# Relating Shapes to Pixels

Whenever you supply a CogShapeModelCollection to PatMax for shape training, you must provide a way for PatMax to transform the shapes' dimensions into the pixel space of the run-time image. There are two ways that you can do this.

- Each CogShapeModel shape has a selected space name property that explicitly defines the name of the coordinate space in which the shape's dimensions are defined. If you supply an image that has an associated coordinate space tree that includes spaces for all of the supplied shapes, then PatMax can use that shape tree to transform the shapes' dimensions into pixel space. (The pixels of this image are ignored.)
- You can supply a TrainShapeModelsTransform that provides the explicit transformation between all of the supplied CogShapeModel objects and a single pixel space. If you supply this transformation, and select the corresponding training mode, the selected space property of the CogShapeModel objects is ignored.