Passive and active imaging at 94 GHz for environmental remote sensing

David Macfarlane, Duncan Robertson, Scott Cassidy, Henry M Odbert, Michael James, H Pinkerton, Geoff Wadge

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

1 Citation (Scopus)


We report on the use of the All-weather Volcano Topography Imaging Sensor (AVTIS) 94 GHz dual mode radar/radiometric imager for environmental monitoring. The FMCW radar yields 3D maps of the terrain whilst the passive radiometer records brightness temperature maps of the scene. AVTIS is a low power portable instrument and has been used operationally to survey terrain at ranges up to 6 km. AVTIS was originally developed for the ground-based measurement of active volcanoes and has been used successfully to measure the Arenal Volcano in Costa Rica and the Soufriere Hills Volcano on Montserrat. However, additional environmental remote sensing applications are emerging for this technology and we will present details of how the instrument is used to perform terrain mapping and thermal surveys of outdoor scenes.

The extraction of digital elevation maps is the primary function of the AVTIS radar mode. We review this process covering range drift compensation, radar cross section (RCS) histogram analysis and thresholding, and georeferencing to GPS. Additionally, we will present how careful calibration enables RCS imaging of terrain and the extraction of the intrinsic reflectivity of the terrain material (normalized RCS, or sigma-nought) which can potentially be used to classify terrain types. We have validated the passive mode imagery against infrared thermal imagery and they show good agreement once the differences in spatial resolution are accounted for. This comparison also reveals differences in propagation due to obscurants (steam, gas, ash) in the two wavebands.

Original languageEnglish
EditorsDA Wikner, AR Luukanen
Place of PublicationBELLINGHAM
PublisherSociety of Photo-Optical Instrumentation Engineers (SPIE)
Number of pages7
Publication statusPublished - 2013
EventConference on Passive and Active Millimeter-Wave Imaging XVI - Baltimore, Moldova, Republic of
Duration: 2 May 2013 → …

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X


ConferenceConference on Passive and Active Millimeter-Wave Imaging XVI
CountryMoldova, Republic of
Period2/05/13 → …


  • Millimeter wave imaging
  • radar
  • radiometry
  • radar cross section
  • FMCW
  • remote sensing
  • volcanology
  • 94GHZ

Cite this

Macfarlane, D., Robertson, D., Cassidy, S., Odbert, H. M., James, M., Pinkerton, H., & Wadge, G. (2013). Passive and active imaging at 94 GHz for environmental remote sensing. In DA. Wikner, & AR. Luukanen (Eds.), PASSIVE AND ACTIVE MILLIMETER-WAVE IMAGING XVI (Proceedings of SPIE; Vol. 8715). Society of Photo-Optical Instrumentation Engineers (SPIE).