1 / 8

Goals

Goals. Define a conceptually and computationally compatible definition of flat one based on the perception of flat can be applied globally Test the feasibility of open source software for conducting large-scale geographic analysis Produce a ‘flat map’ for the continental US

jara
Télécharger la présentation

Goals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Goals • Define a conceptually and computationally compatible definition of flat • one based on the perception of flat • can be applied globally • Test the feasibility of open source software for conducting large-scale geographic analysis • Produce a ‘flat map’ for the continental US • Eerr…I mean Kansas The Flat Map:A Perception Approach To Modeling Flat Terrain Joshua S. Campbell PhD Candidate - Geography University of Kansas GIS Day – 18 Nov 2009

  2. Conceptual Flat • Based on the human perception of flat • a terrain geometry interpreted by human vision • can occur in association with any type of landform (plains, river valleys, plateaus, glacial outwash...) • is not tied to any specific geomorphic process, (erosion/sedimentation, aeolian/fluvial/glacial)

  3. When does flat stop being flat? Calculate visibility at sea: Visibility (in miles) = (1.17 x sqrt (height)) x 1.15 Height = 6 ft Visibility = 3.3 miles or 5,310 meters A model of flat

  4. 30 meter rise 5,310 meter view Computation Flat • Multi-neighborhood DEM analysis (90m SRTM) • View to the horizon (3.3 miles) • 8 directions (N, NE, E, SE, S, SW, W, NW) • Minimum threshold of 0.32 degrees • Local Slope (3 x 3 window: 270m) 0 - 3% slope = flat

  5. 64-bit processing

  6. GRASS Processing in QGIS • r.in.gdal (55 times) • r.patch (mosaic) • g.region (change extents - tricky) • r.mapcalc (conditional statements: subset) • r.slope • r.horizon (8 directions) • r.recode (produce index layers) • r.mapcalc (sum: produce index) • r.statistics (zonal stats) • r.out.gdal (export to geotiff)

  7. Thank You! Presentation, KML files, and upcoming paper will be available at my blog: http://www.disruptivegeo.com ~2% of Kansas is flat

More Related