Mapping change

• Satellites show damage from 2021 tornadoes. (NASA Worldview)
• Change in NDVI (plant health).
• Site surveys.

Errors!

• The dreaded 999999 ArcGIS Pro error.
• Diabolically unknown.
• How to diagnose and fix is a challenge.

Many python functions

• can be run via a GUI tool.
• Extract by Mask is one.
• Search Analysis > Tools for the tool name.

GUI Tools

• Why not just use the GUI?
• We can but it's a lot of clicking
• and we can't save/code our workflow.

From kyraster.ky.gov admin

"I remember last time we dealt with this and were able to get around it. Unfortunately, I’ve seen more issues pop up recently. I hope its transient too. Sorry."

Solution for now

• Use the explore-lidar.ipynb Notebook
• to download and process lidar data for DEM/DSM.
• Do not use kyraster.ky.gov elevation services.

April 2 Update

• Reports that error has cleared
• but don't know why it happened.
• Use with caution for now.

Pauer Cartography Award

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

Videos

• Modules 05 and 06
• are posted together.

Your sites from mod 5

Review

First goal

• How much of x is in (or near) y?
• Highly accurate and precise data now.
• Essential GIS.
• Module 2: How many populated places near Kentucky's highest park?

Second goal

• Where x_n is in y, z exists.
• x_n is any number of variables.
• z is not directly observed, but predicted.
• Spatial modeling.
• Module 3: Where to have a picnic and where are tall trees?

Third goal

• Test our prediction in the field.
• Visualize and measure complicated data.
• Make a useable artifact.
• Module 4 & 5: Field mapping and Intro to lidar.

Current goal

• Where x_t1 != x_t2, e occurred.
• x_t is same variable at different times.
• != is not equal to – they are different.
• e is an event that caused the difference.

Witness

• Global climate change from satellites.
• Local from differences in elevation.
• From your daily adventures.

We will use data KyFromAbove and kyraster.ky.gov

but the same techniques can be applied to other sources of data.

Change

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 30m and align across years.
• Class codes (land cover types) are the same across years.
• c_t1 != c_t2 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 = DEM_t1 - DEM_t2
• 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 = DSM_t1 - DSM_t2
• You'll need two point clouds to do this.

Visualization

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

Custom coloring techniques

Colorize

• 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.

Colorize

• Color point cloud with explore-lidar.ipynb
• which overwrites previous colorization.

Colorize

• Use Notebook at end of slide deck
• which creates new colorized point cloud.
• Or, use the Analysis > Colorize LAS tool in ArcGIS Pro.

In-class task

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

Steps

• Use the notebook from previous slide.
• Find desired AOI lat,lon and buffer distance.
• Run notebook for Phase 1 and create a DSM.
• Run notebook for Phase 2 and create a DSM.

Steps

• Start section "Comparing DSM change"
• and load the two DSMs via their file paths.
• Create a filled and removed raster from the change in surface height.
• Colorize phase 1 with the removed raster and phase 2 with the filled raster.

STOP