EOS Volcanology Logo Interactive Topographic Analysis System (ITAS)

The Interactive Topographic Analysis System (ITAS) was developed to facilitate the analysis and visualization of topographic and related data sets. The primary data sets used to develop ITAS were TOPSAR topography and radar backscatter. TOPSAR is an airborne radar system that is described by Zebker et al. (1992) and Evans et al. (1993).

The ITAS software features a graphical user interface and online help which allows a user to quickly enhance and extract relevant statistics based on polygons or profiles drawn by the user. For volcanology applications, this might include the thickness of lava flows as a function of slope, radar backscatter vs. slope, the cross-sectional area of pyroclastic flow channels as a function of distance from the rim of a volcano, or the spatial distribution and volume of parasitic cinder cones. Further examples of using the ITAS package on TOPSAR data for Vesuvius are given in Mouginis-Mark and Garbeil (1993).

The user must supply a data set which minimally must consist of a digital elevation model (DEM). For better navigating within the image, a shaded relief, radar backscatter, or reflectance map should also be used. The user has the option of working off the DEM, slope map, shaded relief image, or some other coregistered data sets (such as SPOT or Landsat). All images (or layers) must be coregistered.


Evans DL, C Elachi, ER Stofan, B Holt, JB Way, M Kobrick, H Ottl, P Pampaloni, M Vogt, S Wall, J van Zyl, and M Schier (1993). The Shuttle Imaging Radar-C and X-SAR mission. Eos Trans. AGU, 74: p. 145, 157, 158.

Mouginis-Mark, PJ and H Garbeil (1993). Digital topography of volcanoes from radar interferometry: An example from Mt. Vesuvius, Italy. Bull. Volcanol., 55: 566-570.

Zebker, HA, SN Madsen, J Martin, KB Wheeler, T Miller, Y Lou, G Alberti, S Vetrella, and A Cucci (1992). The TOPSAR interferometric radar topographic mapping instrument. IEEE Trans. Geosci. Remote Sens., 30: 933-940.

Capabilities in ITAS include:
DEM image manipulations
Color contour maps, color table map adjustments
User-selected profile in an image
Valley geometry analysis
Yield strength calculations for lava flows
Analysis of profile slopes
Frequency domain analysis: Autocorrelation functions, spectral density
User-selected polygon in an image
Volume above or below a reference plane
Covariance and correlation matrices

The ITAS software and demo images require either Windows NT and IDL version 5 for PC's, or XWindows (OpenWindows or Motif) and IDL version 4 or 5 for Sun computers. IDL, Interactive Data Language, is distributed by Research Systems,Inc.<http://www.rsinc.com>

Download ITAS (University of Hawai'i web server)
Two files are required:

  1. ITAS Program File
  2. For IDL version 4: itas40.tar.Z 0.16 Mb
    For IDL version 5: itas50.tar.Z 0.08 Mb

  3. ITAS Demo Images
  4. For IDL versions 4 and 5: itas_demo_images.tar.Z 1.4 Mb
The ITAS program and demo files are compressed for download. Uncompressed, they take up about 8 Mb of disk space.

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