We present Disambiguation canvas, a technique for selection by progressive refinement using a mobile device and consisting of two steps. During the first, the user defines a subset of objects through the orientation sensors of the device and a volume-casting pointing technique. The subsequent step consists of the disambiguation of the desired target among the previously-defined subset of objects, and is accomplished using the mobile device touchscreen. By relying on the touchscreen for the last step the user can disambiguate among hundreds of objects at once, previous progressive refinement techniques do not scale as well as ours. Disambiguation canvas is mainly developed for easy, accurate and fast selection of small objects, or objects inside cluttered virtual environments. User tests show that our technique performs faster than ray-casting for targets with approximate to 0 : 53 degrees of angular size, and is also much more accurate for all the tested target sizes.