Module 06

Visualizing change (with point clouds)

Yesterday in the Great Smokies
Webcam archive
GEO 409: Advanced GIS

Pauer Cartography Award

  • Submissions are open!
  • Cash prize
  • Traditional cartography, 3D mapping, and web maps
  • Let me know if you want to submit.


  • Modules 05 and 06
  • have been posted.



dtabeyrathne garnieri katyeberry dandelaneyuky crkr226 brianemetz skparker1 LucasRuckdeschel sgsa228 lsisler19 sbti226 CSWALLiN mhwh225


First goal

  • How much of x is in (or near) y?
  • Highly accurate and precise data now.
  • Essential GIS.

Second goal

  • Where xn is in y, z exists.
  • xn is any number of variables.
  • z is not directly observed, but predicted.
  • Spatial modeling.

Current goal

  • Where xt1 != xt2, e occurred.
  • xt is same variable at different times.
  • != is not equal to – they are different.
  • e is an event that caused the difference.


There is nothing permanent except change.

– Heraclitus, 500 BCE

We will be known forever by the tracks we leave.

– Dakota Tribe

Land use change

  • NLCD captured every ~five years (2001-2019)
  • Raster cells are 30m x 30ma and align across years.
  • Class codes (land cover types) are the same across years.
  • ct1 != ct2 if true, change occurred.

In-class task

  • Open the explore-change.ipynb Notebook.
  • Find how much land was developed between 2001 and 2019
  • within 20 miles of your hometown.

Mass terrain modification

  • Dam building. Mountain Top Removal (MTR).
  • Surface mining creates overburden
  • which becomes valley fill.
  • Explore Google Maps

Elevation change

  • Lidar derived DEMs from 2010 to current.(>5ft resolution)
  • USGS DEMs from the early 1990s. (10m resolution)
  • change = DEMt1 - DEMt2
  • If it is not close to 0, change occurred.

In-class task

  • Find a surface mine site
  • and show the change in elevation between the DEMs
  • within two miles of the center of the site.

Above-ground change

  • Compare lidar Phase 1 to Phase 2
  • via their DSMs.
  • change = DSMt1 - DSMt2
  • You'll need two point clouds to do this.


  • Colorize Phase 1 point cloud by amount of removal
  • and Phase 2 by amount of addition.
  • Show both simultaneously.
  • 🤯


  • Point cloud can be colored by any RGB image.
  • Export raster and force rendering to RGB.

Sunrise spring equinox

  • Create hillshade from DSM
  • enabling shadows.

In-class task

  • Color Phase 1 point cloud by amount of removal
  • and Phase 2 by amount of addition.
  • Make a layout showing change.