This paper presents an intensity ratio approach for 3D object profilometry measurement based on projection of triangular patterns. Compared to existing intensity ratio approaches, the proposed one is not influenced by the surface reflectivity and ambient light. Moreover, the proposed intensity ratio is point-by-point-based and thus does not suffer from the influence of surrounding points. The performance of the proposed technique has been tested and the advantages have been demonstrated by experiments. This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-53-2-200. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.