Week 9: Interpolation

Presentation Slides

• Tuesday — Interpolation — Estimating a surface from points: sampling designs, Thiessen polygons, IDW, splines, and kriging, and how to judge which one to trust.
• Thursday — Interpolation Explorer — How wrong is the surface? Error rasters, RMSE and what it hides, checkpoints when there is no truth, whether a ranking survives a change, and Lab 8.

Press F for fullscreen and P for presenter view with speaker notes.

In-Class Practice

• Air Temperature Interpolation (graded, 5 points) — done in class Tuesday; upload a screen capture or photo by 9:30 am, fifteen minutes after class.

Self-check quizzes — not graded; open them on a phone or laptop as often as you like:

• Points Into Surfaces — Five questions on estimating a surface from points: Thiessen polygons, IDW and kriging, which methods give the measured values back, and how you would judge which one to trust.
• How Wrong Is the Surface? — Five questions on what an error raster's sign means, why RMSE squares the errors, what it hides, and judging a surface from checkpoints.

Lab Assignment

Lab 8 — Interpolation Explorer

Due Saturday at 11:59 pm as one PDF report on Learning Suite — 50 points.

Reading Quiz

Read Chapter 12 of GIS Fundamentals, 7th edition (Bolstad).

Quiz 7 — Sampling and Interpolation on Learning Suite: open book, done independently. Due Saturday at 11:59 pm — 20 points.

Note

If you see a discrepancy between Learning Suite and this page, please let me know so I can rectify it.