1 of 2 [north sheet only]. Republic of the Philippines. Board of Technical Surveys and Maps. Republic of the Philippines. Photogrammetric Survey. Sources: BTSM Topographic base map, scale 1:10,000, compiled by photogrammetric methods by the Bureau of Lands, the Bureau of Coast and Geodetic survey and the Board of Technical Surveys and Maps personnel, from 1966 Land Authority aerial phtographs and other sources. Transverse mercator projection. Relief shown by contour lines at 2 meter intervals.