Three-dimensional optical devices are relatively inexpensive and can rapidly acquire body surface scans. Therefore, they can be used as an efficient tool for automatically obtaining landmarks and anthropometric measurements. In this study, we develop an algorithm called DeCIMA (Detecting the Crotch In Mesh Analysis). DeCIMA automatically finds the crotch, as one of the fundamental landmarks on 3D human optical scans. DeCIMA presents a solution for finding the crotch-location even in challenging cases where the subjects’ thighs are connected. We test DeCIMA on 225 scans obtained from 75 human subjects using three different scanners. We compare the crotch height obtained by DeCIMA with the crotch height reported by the proprietary software of the 3D optical scanners. Results show that DeCIMA improves crotch detection and can correctly detect the crotch even for subjects with connected upper thighs.