Advancing cave detection using terrain analysis and thermal imagery

J. Judson Wynne, Jeff Jenness, Derek L. Sonderegger, Timothy N. Titus, Murzy D. Jhabvala, Nathalie A. Cabrol

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Since the initial experiments nearly 50 years ago, techniques for detecting caves using airborne and spacecraft acquired thermal imagery have improved markedly. These advances are largely due to a combination of higher instrument sensitivity, modern computing systems, and pro-cessor-intensive analytical techniques. Through applying these advancements, our goals were to: (1) Determine the efficacy of methods designed for terrain analysis and applied to thermal imagery; (2) evaluate the usefulness of predawn and midday imagery for detecting caves; and (3) ascertain which imagery type (predawn, midday, or the difference between those two times) was most in-formative. Using forward stepwise logistic (FSL) and Least Absolute Shrinkage and Selection Op-erator (LASSO) regression analyses for model selection, and a thermal imagery dataset acquired from the Mojave Desert, California, we examined the efficacy of three well-known terrain de-scriptors (i.e., slope, topographic position index (TPI), and curvature) on thermal imagery for cave detection. We also included the actual, untransformed thermal DN values (hereafter “unenhanced thermal”) as a fourth dataset. Thereafter, we compared the thermal signatures of known cave en-trances to all non-cave surface locations. We determined these terrain-based analytical methods, which described the “shape” of the thermal landscape, hold significant promise for cave detection. All imagery types produced similar results. Down-selected covariates per imagery type, based upon the FSL models, were: Predawn— slope, TPI, curvature at 0 m from cave entrance, as well as slope at 1 m from cave entrance; midday— slope, TPI, and unenhanced thermal at 0 m from cave entrance; and difference— TPI and slope at 0 m from cave entrance, as well as unenhanced thermal and TPI at 3.5 m from cave entrance. We provide recommendations for future research directions in terrestrial and planetary cave detection using thermal imagery.

Original languageEnglish (US)
Article number3578
JournalRemote Sensing
Issue number18
StatePublished - Sep 2021


  • Planetary caves
  • QWIP thermal instrument
  • Regression analysis
  • Terrestrial caves

ASJC Scopus subject areas

  • General Earth and Planetary Sciences


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