I wasn’t able to talk about this before, but now I guess the cat’s out of the bag. About two years ago, we helped a team of archaeologists and filmmakers to visualize a very large high-resolution aerial LiDAR scan of a chunk of dense Honduran rain forest in the CAVE. Early analyses of the scan had found evidence of ruins hidden under the foliage, and using LiDAR Viewer in the CAVE, we were able to get a closer look. The team recently mounted an expedition, and found untouched remains of not one, but two lost cities in the jungle. Read more about it at National Geographic and The Guardian. I want to say something cool and Indiana Jones-like right now, but I won’t.
Figure 1: A “were-jaguar” effigy, likely representing a combination of a human and spirit animal, is part of a still-buried ceremonial seat, or metate, one of many artifacts discovered in a cache in ruins deep in the Honduran jungle. Photograph by Dave Yoder, National Geographic. Full-resolution image at National Geographic.
I have talked about KeckCAVES’ involvement in the Curiosity Mars Rover missions severaltimesbefore, but I just found a set of cool pictures that I have not shared yet. I just saw a redditthread about a VR application to walk on the moon, one commenter asked about doing the same for Mars, and one thing led to another.
Can an application like that be done for Mars? Do we have enough data, and are the data publicly available? The answers are “yes, alreadydone,” “kinda,” and “yes, but,” respectively.
As of my last checking, there are two main sources of topography data for Mars. The older source is an orbital laser range survey done by the Mars Orbiter Laser Altimeter (MOLA). This is essentially a planetary LiDAR scan, and can be visualized using LiDAR Viewer. The two pictures I mention above are these (Figures 1 and 2):
Figure 1: Global visualization of Mars topography using the MOLA data set, rendered using LiDAR Viewer. Vertical scale is 5:1.
Figure 2: Close-up of global Mars topography data set (centered on the canals), showing individual laser returns as grey dots. The scan lines corresponding to individual orbital periods can clearly be identified. Vertical scale is 5:1.
There have been several discussions on the Oculus subreddit recently about how to integrate 2D desktops or 2D applications with 3D VR environments; for example, how to check your Facebook status while playing a game in the Oculus Rift without having to take off the headset.
This is just one aspect of the larger issue of integrating 2D and 3D applications, and it reminded me that it was about time to revive the old VR VNC client that Ed Puckett, an external contractor, had developed for the CAVE a long time ago. There have been several important changes in Vrui since the VNC client was written, especially in how Vrui handles text input, which means that a completely rewritten client could use the new Vrui APIs instead of having to implement everything ad-hoc.
Here is a video showing the new VNC client in action, embedded into LiDAR Viewer and displayed in a desktop VR environment using an Oculus Rift HMD, mouse and keyboard, and a Razer Hydra 6-DOF input device:
I just found this old photo on one of my cameras, and it’s too good not to share. It shows former master’s student Peter Gold (now in the PhD program at UT Austin) working with a high-resolution aerial LiDAR scan of the El Mayor-Cucapah fault rupture after the April 2010 earthquake (here is the full-resolution picture, for the curious).
Figure 1: Former master’s student Peter Gold in the CAVE, analyzing a high-resolution aerial LiDAR scan of the El Mayor-Cucapah fault rupture.
Figure 1: Dawn Sumner, member of the NASA Curiosity Mars rover mission’s science team, interacting with a life-size 3D model of the rover in the UC Davis KeckCAVES holographic display environment. Still image taken from “The surface of Mars.”
The most interesting aspect of this talk, for me, was that the art project and all the software development for it, are done by the “other” part of the KeckCAVES project, the more mathematically/complex systems-aligned cluster around Jim Crutchfield of UC Davis‘ Complexity Sciences Center and his post-docs and graduate students. In practice, this means that I saw some of the software for the first time, and also heard about some problems the developers ran into that I was completely unaware of. This is interesting because it means that the Vrui VR toolkit, on which all this software is based, is maturing from a private pet project to something that’s actually being used by parties who are not directly collaborating with me.
Figure 1: Danny Rey, Tribal Historic Preservation Officer, and Marcos Guerrero, Cultural Resources Manager, representatives of the United Auburn Indian Community, viewing a high-resolution 3D scan of the Maidu Historic Trail and Site in the KeckCAVES immersive visualization facility. In the background Joe Dumit of UC Davis’ Science and Technology Studies, and myself. Photo provided by Marshall Millett.
Marshall has been using KeckCAVES software, particularly LiDAR Viewer (about which I should really write a post), and also the KeckCAVES facility itself and related technology, to visualize his high-resolution 3D models at 1:1 scale, and with the ability to experience them in ways that are not normally possible (most of these sites are fragile and/or sacred, and not available to the public). Part of this work were several visits of community representatives to the KeckCAVES facility, to view their digitally reconstructed historic site (see Figure 1).
We are currently involved in an NSF-funded project to study the changes in global ocean flow patterns in response to past climate change, specifically the difference in flow patterns between the last glacial maximum (otherwise known as the “Ice Age”, ~25000 years ago) and the Holocene (otherwise known as “today”).
In layman’s terms, the basic idea is to use differences in the chemical composition, particularly the abundance of isotopes of carbon (13C) and oxygen (18O), of benthiccore samples collected from the ocean floor all around the world to establish correlations between sampling sites, and from that derive a global flow model that best explains these correlations. (By the way, 13C is not the carbon isotope used in radiocarbon dating; that honor goes to 14C).
This is a multi-institution collaborative project. The core sample isotope ratios are collected and collated by Lorraine Lisiecki and her graduate students at UC Santa Barbara, and the mathematical method to reconstruct flow patterns based on those samples is developed by Jake Gebbie at Woods Hole Oceanographic Institution. Howard Spero at UC Davis is the overall principal investigator of the project, and UC Davis’ contribution is visualization and analysis software, building on the strengths of the KeckCAVES project. I’ve posted previously about our efforts to construct low-cost immersive display systems at our collaborators’ sites so that they can use the visualization software developed by us in its native habitat, and also collaborate with us and each other remotely in real-time using Vrui’s collaboration infrastructure.
So here is the first major piece of visualization software developed specifically for this project. It was developed by Rolf Westerteiger, a visiting PhD student from Germany, based on the Vrui VR toolkit. Here is Rolf himself, using his application in the CAVE:
PhD student Rolf Westerteiger using his immersive visualization application in the KeckCAVES CAVE.
This application reads a database of core sample compositions created by Lorraine Lisiecki, and a reconstructed 3D flow field created by Jake Gebbie, and puts both into a global three-dimensional context. The software shows a block model of the Earth’s global ocean floor (at the same resolution as the 3D flow field, and vertically exaggerated by a significant factor), and allows a user to interactively query and explore the 3D flow.
The primary flow visualization method is line integral convolution (LIC), which creates dense and intuitive visualizations of complex flows. As LIC works best when applied to 2D surfaces instead of 3D volumes, Rolf’s application is based on a set of interactively controllable surfaces (one sphere of constant depth, two cones of constant latitude, two semicircles of constant longitude) which slice through the implicitly-defined 3D LIC volume. To indicate flow direction, the LIC texture is animated by cycling through a phase offset, and color-coded by either flow velocity or water temperature.
The special thing about this LIC visualization is that the LIC textures are not pre-computed, but generated in real time using the GPU and a set of GLSL shaders. This allows for even more interactive exploration than shown in this first result; a user could specify arbitrary slicing surfaces using tracked 3D input devices, and see the LIC pattern displayed on those surfaces immediately. From our experience with the 3D Visualizer software, which is based on very similar principles, we believe that this will lead to a very powerful exploratory tool.
A secondary flow visualization method are tracer particles, which can be injected into the global ocean at arbitrary positions using a tracked 3D input device, and leave behind a trail of their past positions. Together, these two methods provide rich insight into the structure of these reconstructed flows, and especially their evolution over geologic time.
A third visualization method is used to put the raw data that were used to create the flow models into context. A set of labels, one for each core sample in the database, and each showing the relative abundance of the important isotope ratios, are mapped onto the virtual globe at their proper positions to enable visual inspection of the flow reconstruction method.
Unfortunately, Rolf had to return to Germany before we were able to film a video showing off all features of his visualization application, so I had to make a video with myself standing in for him:
The next development steps are to replace the ocean floor block model read from the flow file with a high-resolution bathymetry model (see below), and to integrate the visualization application with Vrui’s remote collaboration infrastructure such that it can be used by all collaborators for virtual joint data exploration sessions.
Global high-resolution bathymetry model at 75x vertical exaggeration. View is centered on Northern Atlantic.
