Since LADAR data is collected from a static sensor mounted on a tripod, it is essential to scan each scene from a known georeferenced location if the data is to be used in a GIS.  LADAR scans were originated from benchmarks (permanent bolts drilled into the rock) that were placed around four of the sinkholes (Zacaton, Caracol, La Pilita, and Azufrosa).  Often benchmark positions are measured using GPS, but due to the fact that many scanning locations were under rock overhangs or beneath a thick tree canopy, additional means of referencing had to be taken.  We did obtain a good differential GPS fix on one benchmark (the southern LADAR benchmark at Zacatón), and this was identified as the x - y reference point.  A nearby monument with accurate elevation data (from a previous Mexican survey) was used to reference the z-axis.  We then used a Total Station survey instrument to precisely locate each of the LADAR scanning benchmarks.  This was a laborious effort that took several weeks in the hot August sun.  Once completed, the origins of each of the 12 LADAR scans made of the four sinkholes can be properly georeferenced and imported into the GIS geodatabase.

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