1. A method for providing an interface for polyp annotation, segmentation, and measuring in computed tomography colonography (CTC) volumes, comprising: receiving an initial polyp location in a CTC volume; automatically segmenting a polyp in the CTC volume based on the initial polyp location by: detecting a polyp tip in a neighborhood of the initial polyp location, fitting a local polar coordinate system to a colon surface in the CTC volume based on the detected polyp tip, the local polar coordinate system including a plurality of axes, detecting polyp interior and polyp exterior voxels along each of the plurality of axes of the local polar coordinate system, and segmenting a boundary of the polyp in the CTC volume by detecting a boundary voxel for each of the plurality of axes of the local polar coordinate system based on the detected polyp interior and polyp exterior voxels; displaying the segmented polyp in the CTC volume in a user interface; receiving a user input via the user interface to modify the segmented polyp; and re-segmenting the segmented polyp based on the received user input.