GMSimViz: Automated 3D Visualization of Ground Motion Simulation with Generic Mapping Tools (GMT)

Overview

GMSimViz is an automation tool that produces an animated 3D visualization of geological faults, ground motion and other earthquake related data. It uses the Generic Mapping Tools(GMT) to create individual frames, and join them by FFmpeg to create a movie file.

A fully featured result is available at https://youtu.be/qZkOTI4x_cc

Screenshots of a GMSimViz-generated animation

November 2023 Update

Before and after. Try to take into consideration the depth of the fault to make sure it fits on the screen when tilted. This is done by estimating the geographical to page coordinate ratio and can be modified with the --shift-factor parameter. The actual z-scaling factor is a dependency which changes after making this adjustment.

New parameters to control the max and min tilt range when facing the fault with --tilt-min and --tilt-min. The major tilt to show the fault below the surface can also be adjusted from the previous default of 1 degree tilt using --tilt-dip.

Installation

Dependencies

The GMSimViz depends on the following software packages.

• Python 3. Which version do I have? Run /usr/bin/env python --version.
• Numpy (https://www.numpy.org https://pypi.org/project/numpy/).
• MPI4Py (https://bitbucket.org/mpi4py/ https://pypi.org/project/mpi4py/) including mpi backend (https://www.open-mpi.org dependency of mpi4py)
• H5Py (http://www.h5py.org/ https://pypi.org/project/h5py/) including hdf5 backend (https://support.hdfgroup.org/HDF5/ dependency of h5py)
• GMT 5.4.5 or 6.x versions should work. Anything older will not be supported. Ghostscript 9.18, 9.50, 9.53 were working, between 9.18 and 9.50 were found to produce glitches as well as 9.52.
• FFMpeg built with image2/png, h.264 encoder support (standard installation).
• gawk

For testing:

• pytest with pytest-mpl and matplotlib
• imageio (tested with 2.1.1) or scipy prior to 1.2 with pillow.

Linux

Install the packages for the above mentioned dependencies. Names vary between distribution repositories. On Ubuntu or other Debian-based Linux distributions, most of the packages can be installed by the following command. If your system default Python is version 3, install the python3-* packages instead of python-*. shell sudo apt install python2.7 python-numpy python-mpi4py python-h5py ffmpeg gawk git If you are using a Debian based distribution, you will also need to have installed the separated -dev packages in order to compile GMT. shell sudo apt install libpng-dev

GMT

GMT versions earlier than 5.2 have some outstanding issues/API differences, can't work with GMSimViz. A version later than 5.4.4 is recommended, and at the time of writing, the latest development source obtained directly from the repository (A release r19922 fully verified, r20495 also seems fine), 6.x releases seem to work too. Instructions for GMT installation is available at http://gmt.soest.hawaii.edu/projects/gmt/wiki/BuildingGMT . You should compile with PNG support enabled (check configure output, make sure headers are available).

Versions 5.4.3 and 5.4.4 will draw outlines of the fault plane and hypocentre location on the surface rather than at depth (bug) but otherwise work fine.

Make sure the gmt binary is in the PATH. If gmt is installed in /usr/local/bin and gmt is not already available in the PATH, add it to the PATH: shell export PATH=$PATH:/usr/local/bin You can add the line above to ~/.bashrc to make it persistent.

GMSimViz

Download GMSimViz: shell git clone git@github.com:ucgmsim/GMSimViz.git

Install with the following command (automatically downloads resources from the Github release). shell sudo python setup.py install In case of no root priviledge, --user option can be used.

shell python setup.py install --user You may use python2, python3, python2.7 etc. instead of python where you want to use a specific verision.

To use pip to install instead: shell pip install . --user You will need to have an environment variable storing the resources location if you use pip or if they move: shell export GMT_DATA="/path/to/resources" This can be added to a ~/.bashrc file for permanent storage.

Other systems

On Mac OSX, GMT can be installed from homebrew (https://brew.sh/).

Sample Data

Sample data is provided, it contains smaller data sets from multiple earthquakes to make a feature-full demo.

GMT may produce error messages like the one below in versions from around 5.4.4 with GMSimViz. These can be ignored. shell grdimage: Error: (x_max-x_min) must equal (NX + eps) * x_inc), where NX is an integer and |eps| <= 0.0001. grdimage (gmtlib_read_grd_info): Use grdedit -A on your grid file to make region and increments compatible [GMSimViz/resources/Topo/srtm_all_filt_nz_i5.grd] grdimage: Error: (x_max-x_min) must equal (NX + eps) * x_inc), where NX is an integer and |eps| <= 0.0001. grdimage (gmtlib_read_grd_info): Use grdedit -A on your grid file to make region and increments compatible [GMSimViz/resources/Topo/srtm_all_filt_nz.grd]

The most simplest output is a single frame (image) facing the fault plane. This case only requires the SRF file as the parameter: shell mpirun gmsimviz sample_data/fault.srf The output will be in the current directory with the same basename as the SRF file but with _perspective.png added to the end.

An animation can be created from an SRF that shows the rupture propagating. It can be expected to take around 12 minutes to complete on a decent personal machine. Here is an example using 8 processes for a machine with 8 cores (including hyperthreading). An example of what is expected is available at https://youtu.be/nTtqDxGVUM ```shell mpirun -n 8 gmsimviz sampledata/fault.srf -a --crude --title "Fault Animation" --dpi 120 --downscale 1 `` Animations will be saved in the current working directory with the same name as the SRF file but with a.m4vextension../fault.m4v` in the above and below examples.

The fully featured sample animation below takes about 45 minutes with -n 8 on a v4 E5-2620 (2.1 GHz). Slave processes begin work after about 3 minutes and frames will start appearing in the temporary folder (in the same folder as the SRF file, sampledata/GMTWDPERSPECTIVE). When complete, the video is available in the working directory and the temporary folder is removed by default. The expected output is available at https://youtu.be/6TFj5HXp3MU ```shell mpirun -n 8 gmsimviz sampledata/fault.srf -a --crude --title "Sample Animation" --dpi 120 --downscale 1 -x sampledata/xyts.e3d --liquefaction-s sampledata/liquefactions.hdf5 --liquefaction-p sampledata/liquefactionp.hdf5 --landslide-s sampledata/landslides.hdf5 --landslide-p sampledata/landslidep.hdf5 --paths sampledata/transport ```

Here are details for command options:

• -n number of processes to start. Minimum is 2, 8 is a good choice for systems with only 8 cores. It is recommended to run on a machine with many cores.

• srf_file not optional. Path to a fault in standard rupture format containing the plane header (https://scec.usc.edu/scecpedia/StandardRuptureFormat).

• -a create animation instead of static image showing the slip distribution only. Will animate the progression of slip if no other input data are given.

• --crude this will produce a quick result. No topography or roads are plotted, low resolution coastlines are used and overlays have lower resolutions. This is required for faults outside of the New Zealand area because the higher resolution topography is only available here. Alternatively, replace the topography files in the resources directory with your own.

• -f set the framerate of the animation eg: 30. The minimum is 5 and each frame is independent so a framerate of 60 would take roughly twice as long as 30.

• --title title on the movie, the default is the basename of the SRF file. In the screenshots at the top of the page, the title is "Kaikoura 2016".

• --dpi dpi of output. Frames are 16 inches x 9 inches so 240 will produce 4k output, 120 for FullHD.

• --downscale render at higher resolution and then downscale. Prevents jitter in object positioning and increases definition of ground motion etc. 8 is ideal for a smooth result, highly recommended.

• -x XYTS file. This is an output created by the EMOD3D software that simulates ground motion. This provides the simulation domain and ground motion data. The XYTS file format is described here

• --liquefaction-s and --landslide-s Liquefaction and/or landslide suceptibility HDF5 file. Longitude and latitude is stored as an array under 'x' and 'y' respectively. model is a 2D array containing the actual values in the shape (y, x).

• --liquefaction-p and --landslide-p As above for the probability from given event.

• --paths Folder containing transport network in GMT path format (with .gmt extention, colour and pen data in path headers) with optional GMT legend files (same basename with .legend extention). Files are sorted numerically, underscore separators can be used. Sample data provided.

• --gm-cut Cut the time series of the xyts file given with -x short to this many seconds. Eg if the xyts timeseries is 300 seconds but nothing happens after 200, use --gm-cut 200.

• -t Sets the time (s) for major animation transitions such as when originally facing the slip distribution from initial camera position.

• -m Sets the minor tranition time (s) for transitioning between different segments of the animation.

• -p Sets the time (s) to pause for when showing an image such as fault under ground and liquefaction/landslide images.

• -d Sets the delay (s) at the start of the animation before the camera starts moving.

• -e Sets end delay (s) at the end of the animation to prevent sudden end after moving the camera.

• -r Fix the rotation of the camera to bearing (deg). eg: 0 to face north always.

• --temp Continue from the given previous temporary directory, will not re-render frames which are complete.

• -k Keeps the temporary directory (containing all frames) once animation is complete.

To list the parameters, run: mpirun gmsimviz -h

Thanks

The QuakeCoRE team would like to thank:

• Eric Thompson from USGS for collaborating with us and providing data and software relating liquefaction and landslide analysis.
• The Generic Mapping Tools team, especially Paul Wessel for GMT support and quickly fixing issues we ran into while using GMT.