Wednesday, March 31, 2021

TouchTerrain Story Map

I've made my first ever ESRI Story map about TouchTerrain: It re-uses some of the material from the AGU 2020 conference poster but is far slicker!

Tuesday, March 30, 2021

Version 3.2.1: Z-scale bug fix

Z-scale fix 

  • Well, this is embarrassing! Simon Scherrer recently pointed out that my mesh models where hilariously tall when applying a large z-scale. 
  • Turns out that at one point I had done the z-scaling in one function, then forgot about it and applied it again in another function! 
  • While easily fixed, this means that any z-scale larger than 1.0 was wrong (not sure since when, must be several years ...). For most users that's likely not an issue b/c it wasn't that obvious at low (>1.0) z-scales and many (including) myself have no real world experience with how a certain z-scale should properly  look like. (This is what convinced me that my old z-scale of 5 was WAY too much! Also, I like that they call the z-scale Boost factor!)
  • Also, I think most user would have dialed in a appropriate z-scale  based on visual inspection. However, if you've been using TouchTerrain for anything scientific where proper z-scale matters you should account for my error and either correct your effective z-scale to the square of what you requested pre version 3.2.1 or re-do you model with the new (correct) z-scale method now in place. 
Old (pre version 3.2.1) z-scale of 5 aka Mordor mode!

Hillshaded relief with proper z-scale of 5

Fixed (>= version 3.2.1) z-scale of 5

  • Again, thanks to Simon Scherrer for bringing this to my attention!

Friday, March 12, 2021

What's new in TouchTerrain Version 3.2?

Docker version of TouchTerrain

  • I created a Docker image of TouchTerrain that makes is easy(er) to run the stand-alone version via a jupyter notebook.
  • After installing the image and running the container, you will have a virtual Linux box running inside your PC/Mac, with all required python packages already installed.
  • Shell scripts are provided to install the latest version of TouchTerrain and to run a jupyter server inside the container. The server that can be accessed through your standard, local browser and you can download and upload files through jupyter.
  • A new notebook (TouchTerrain_jupyter_for_starters.ipynb) will hopefully make is easy for beginners to work through the workflow of creating a 3D terrain model file in standalone mode.
  • The github repo for the Docker version is: 

Added two new DEM sources:

  • NRCan/CDEM: The Canadian Digital Elevation Model (CDEM) is part of Natural Resources Canada's (NRCan) altimetry system and stems from the existing Canadian Digital Elevation Data (CDED). The CDEM is comprised of multiple DEMs with varying resolutions. These vary according to latitude and have a base resolution of 0.75 arc-seconds (about 20m).

  • AU/GA/AUSTRALIA_5M_DEM: The Digital Elevation Model (DEM) 5 Metre Grid of Australia derived from LiDAR model represents a National 5 metre (bare earth) DEM which has been derived from some 236 individual LiDAR surveys between 2001 and 2015 covering an area in excess of 245,000 square kilometres. All available 1 metre resolution LiDAR-derived DEMs have been compiled and resampled using a neighbourhood-mean method to 5 metre resolution.

Note that both DEMs are image collections, rather than a single image as can seen here for the Australia DEM (black patches):

Zoomed into an urban area. As Lidar cannot image water surfaces, these areas will always be set to NaN and will be omitted from the terrain model.

Even at "only" 5 m resolution, it still shows some nice details!

CDEM coverage: