Terrain generalization with multi-scale pyramids constrained by curvature

B. Jenny, L. Hurni

Research output: Chapter in Book/Report/Conference proceedingConference PaperOtherpeer-review

Abstract

This paper presents a method for terrain generalization using Laplacian pyramids. The method pre-processes digital terrain for generating cartographically generalized 3D maps. Map authors can attenuated or amplify selected frequency bands of the terrain with a graphical interface imitating an audio equalizer. Ridge lines and valley lines are localized by curvature indices, and their characteristic shapes are preserved or emphasized using additional sets of equalizer controls. Frequency bands are adjusted separately for the foreground and the background to remove visually disturbing terrain detail in the background. This is relevant for 3D maps in central perspective projection considerably compressing distant terrain features. The proposed generalization method was implemented in Terrain Equalizer, a free and open-source application providing a graphical interface with interactive 3D previews (available at http://www.terraincartography.com/). Using this application, disturbing high frequency details can be easily removed and major mountain forms can be accentuated. The level of generalization can be adjusted seamlessly from the foreground to the background of the 3D map. Topographic break lines, such as ridge or valley lines, are successfully preserved, which is important for conveying the characteristic shape of a generalized terrain.

Original languageEnglish
Title of host publicationGeospatial Data and Geovisualization: Environment, Security, and Society
Subtitle of host publicationSpecial Joint Symposium of ISPRS Commission IV and AutoCarto 2010 in conjunction with ASPRS/CaGIS 2010 Special Conference, November 15-19, 2010, Orlando, Florida, USA
Place of PublicationHannover, Germany
PublisherInternational Society for Photogrammetry and Remote Sensing (ISPRS)
Number of pages7
Publication statusPublished - 2011
Externally publishedYes

Publication series

NameISPRS Archives
PublisherISPRS
Number4
VolumeXXXVIII

Keywords

  • DEM frequency filtering
  • Laplacian pyramid
  • Terrain Equalizer
  • Terrain generalization

Cite this

Jenny, B., & Hurni, L. (2011). Terrain generalization with multi-scale pyramids constrained by curvature. In Geospatial Data and Geovisualization: Environment, Security, and Society: Special Joint Symposium of ISPRS Commission IV and AutoCarto 2010 in conjunction with ASPRS/CaGIS 2010 Special Conference, November 15-19, 2010, Orlando, Florida, USA (ISPRS Archives; Vol. XXXVIII, No. 4). International Society for Photogrammetry and Remote Sensing (ISPRS). http://www.isprs.org/proceedings/XXXVIII/part4/