Patent ID: 8510814

Claim:
A computer-implemented method for authenticating a user of a computer comprising: selecting plurality of 3-dimensional models from a library of 3-dimensional models, each of the 3-dimensional models in the library: containing geometric shape data for a respective object in three spatial dimensions; and having an associated parameterization comprising a set of one or more rendering parameters specific to said model, each parameter having pre-defined thresholds and/or constraints such that said model remains recognizable by a human, wherein the parameterization of one or more of the 3-dimensional models in the library comprises a parameter determining a deformation of the respective geometric shape data for the respective object; for each respective selected model, randomly varying the one or more rendering parameters, within the respective pre-defined thresholds and/or constraints for the one or more rendering parameters specific to said model; generating a 2-dimensional image based on the result of the varying step, such that each respective selected model remains recognizable by a human in said 2-dimensional image; generating metadata based on each respective selected model, and the one or more rendering parameters, wherein the metadata comprises: visibility regions identifying where each respective selected model is not occluded in the 2-dimensional image; one or more descriptors identifying categorical properties of one of the respective selected models; and one or more descriptors identifying visual properties of one of the respective selected models, wherein the categorical and visual properties are recognizable by a human in said 2-dimensional image; generating a prompt based on at least one of the categorical descriptors and at least one of the visual descriptors; communicating the 2-dimensional image for presentation at the computer; communicating the prompt for presentation at the computer; receiving user input data concerning the 2-dimensional image; comparing the metadata and the user input data to determine if the user interacting with the computer is a human user, the comparing comprising a comparison of the user input data with the visibility regions; and authenticating or not authenticating based on the result of the comparing step.