KenMankoff

Pine Island Glacier and Pine Island Bay

Pine Island Bay in the southeast Amundsen Sea, Antarctica, on 16 Nov 2008. Upwelling, melt-laden outflow plumes emerge from beneath the adjacent Pine Island Glacier ice shelf (top center) and mix in the bay waters. Warm red colors show sea surface temperatures more than a degree warmer than the near-freezing dark blue color. Cyclonic circulation in the bay is framed by the ice shelf, land ice and sea ice, in gray-scale with the darker shades colder. Landsat Enhanced Thematic Mapper Plus image, thermal infrared (channel 6H), subset of scene #LE72331132008321EDC00.

@article{Mankoff:2012The-role,
	Title = {{The role of Pine Island Glacier ice shelf basal
                  channels in deep water upwelling, polynyas, and
                  ocean circulation in Pine Island Bay, Antarctica}},
	Author = {Kenneth D. Mankoff and Stanley S. Jacobs and
                  Slawek M. Tulaczyk and Sharon E. Stammerjohn},
	Journal = {Annals of Glaciology},
	Number = {60},
	Volume = {53},
	Year = {2012}}

Tags: Antarctica, ice, map, PhD, Pine Island Glacier, Places, publication, Research, Visualization

Kinects as sensors in earth science: glaciological, geomorphological, and hydrological applications

Last week I presented a poster at the 2011 AGU Fall Meeting. It has generated some press thanks to an article in Wired. If you are interested in the poster it is available by clicking on the image below.

AGU Poster: `Kinects as sensors in earth science: glaciological, geomorphological, and hydrological applications`

@conference{Mankoff:2011Kinects,
  Author = {Kenneth D. Mankoff and Tess Alethea Russo and
            Benjamin Kenneth Norris and Saffia Hossainzadeh and
            Lucas H. Beem and Jacob I. Walter and
            Slawek M. Tulaczyk},
  Title = {{Kinects as sensors in earth science: glaciological,
            geomorphological, and hydrological applications}},
  Address = {San Francisco, CA},
  Booktitle = {American Geophysical Union, Fall Meeting},
  Month = {December 5 - 9,},
  Note = {Abstract \#C41D-0442.},
  Year = {2011}}

Tags: Kinect, Media, PhD, publication, Research

Kinect Go Kit for fieldwork

Following up on my previous post about using the Kinect for earth science applications, I’m documenting the Kinect Go Kit I built for fieldwork.

I travel with two Kinects, two power supplies, and two computers in case one gets damaged or destroyed in the field, although only one computer is in the kit.

The Netbook is a cheap $240 computer running Ubuntu and the libfreenect software stack at a minimum. I have also found it useful to have more advanced data collection software (ROS, RGBDemo, RGBDSLAM), and some analysis software (CloudCompare, points2grid, Viewpoints, etc.). This netbook works fine for raw data dumps from the libfreenect ‘record’ program. It can run the more computationally expensive scene stitching algorithms such as RGBDSLAM, but it takes about 10 seconds per stitch, while a more powerful laptop (but still a few years old) can do it at 0.5 to 1 Hz. Since ‘record’ collects about 1.5 GB of data per minute, it is good to have a lot of free space on the hard drive.

The plugs and cables are shown laid out below, and in addition, some velcro straps are stored in that compartment, used to attach the Kinect to the tripod arm.

The Pelican 1510 case supports two levels, and the lower level looks like this:

Battery #1 is a 12 V 5 Ah sealed led acid battery. It provides >5 hours of Kinect runtime, about equal to the runtime of the netbook.

Battery #2 is 8 AA batteries (12 V), and underneath is an 8 AA battery holder and a battery charger. If I need to turn the Kinect on for a short amount of time and want to travel lightly, these will do.

As shown above the cord to the Kinect can be cut and alligator clips or some other electrical termination can be attached. I often have wall power and have attached clips to the detached plug so I can use it as originally intended. However, when in the field, the clips can connect directly to the 12 V battery or the AA battery pack.

The Kinect Go Kit above is close to the minimum necessary for fieldwork. Things that I would like in it, but are not yet, include:

• Tape measure
• Liquid container (tupperwear) and opaque liquid (or additive) so that any scene can have a defined flat surface
• Sling for under tripod to hold battery, netbook, protecting equipment and keeping it off the ground
• Counter weight for tripod arm

Additional tools I have found handy to have with me in the field include, but are not limited to, the following:

• External hard disk for backups
• Zip-ties to complement the Velcro straps
• Multimeter
• Spare notebook, perhaps with a more powerful CPU, for scene stitching
• Rope or other ‘image noise’ for scene stitching with RGBSLAM when working in environments that have ‘self similar’ scenes (no good tie points)
• Mounting systems for long term deployment
• Trashbags for environmental protection

 

Tags: Computers, HowTo, Kinect, PhD, Research

Kinect for Earth Scientists

We have successfully used a Kinect outdoors to study ablation on a glacier, map a subglacial cave in 3D, and tested it in a variety of hydrological situations (imaging roughness on the base of a stream, calibrating the Kinect data through water, and imaging surface waves). Results will be presented at the 2011 AGU conference.

There are a variety software interfaces to the Kinect. One high-level tool that is easy to use (binaries provided, no need to compile source, supports ‘scene painting’) is RGB-Demo. It is a good tool to start with if you want to work with the Kinect.

However, most Kinect software and calibrations so far have been developed by the robotics and computer vision communities. I am grateful for the work they have done, but those communities have different data needs than earth scientists. For example, quadrotor obstacle avoidance (link (PDF), link) has distance measurement errors that appear to be on order cm, but it still works fine as the helicopter avoids obstacles by an amount larger than the error.

Earth scientists should aim for a better model of the world than the one currently provided by the Kinect and its primary users. I suggest recording and storing the raw digital numbers (DN) from the Kinect rather than higher-level auto-calibrated real-world coordinates. It will require more post-processing, but storing the DNs will allow the data to be re-processed as better calibrations are developed. In addition, the low level recorder operates at 30 Hz and the higher level point-cloud products currently do not record data at that rate.

The best supported low-level interface is the LibFreenect Fakenect record program. It dumps the uncalibrated RGB and depth images to a folder at 30 Hz until you kill the process. Uncalibrated means both that the depth data is in sensor units, and that the depth and RGB images are not aligned. You can easily convert the depth data to real world x,y,z coordinates using existing published algorithms (link, link, link, and many others exist on the web), but importantly the raw data is stored and can be used with better calibrations in the future.

After processing the raw ‘record’ data, you can work with the point cloud data or DEMs using a variety of standard software for pointclouds, LiDAR, etc. I have had great success with CloudCompare and Poinst2Grid, in addition to custom code in MATLAB, IDL, and Python. A good list of software is available at the NSF OpenTopography site.

To work with the depth data to we initially use the following algorithms found on the various sites dedicated to Kinect hacking. The data provided by these algorithms is sufficient for certain uses, and for testing algorithms and visualizations, while better calibrations are performed.

DN to distance (source):

k1 = 1.1863d
k2 = 2842.5d
k3 = 0.1236d
Z = k3 * tan( double( DN ) / k2 + k1 )

XYZ to world (source):

Xres = 640
Yres = 480
FovH = 1.0144686707507438 (rad)
FovV = 0.78980943449644714 (rad)
XtoZ = tan( FovH / 2 ) * 2
YtoZ = tan( FovV / 2 ) * 2
X = ( X_pixel / Xres – 0.5 ) * Z * XtoZ
Y = ( 0.5 – Y_pixel / Yres ) * Z * YtoZ

Question or comments? Post below…

Tags: Code, Computers, HowTo, Kinect, Research

Astronaut Postcard

I got a postcard from NASA. Presumably so did everyone who applied last time. I’ll apply again. Third times a charm? Statistically unlikely as the global governments (NASA, ESA, JAXA, Roscosmos, CSA) hire about 30 per decade. Not including the CNSA, I have no idea how many they hire. But, it is always fun to try, and I doubt they hire anyone who doesn’t apply…

Tags: NASA, Personal, Space

Kinect Video from Microsoft

It has been almost one year since the Kinect was released, and there have been some amazing projects that use it. Microsoft appears to be embracing the hackers and highlights some of the non-video-game related uses in a new video:

Tags: Computers, Kinect, Research, Video

Fridge

In which I record the temperature of my fridge and surrounding environment, and track events that take place involving the fridge, in order to answer the question,

Can I unplug my fridge at night without ruining my food?

Tags: Personal, Visualization, website

BUBBLES And A Fish

Bubbles is a small ROV built from a kit with a customized camera mount for looking up at ice from below and down at the bottom. Her construction was motivated by some underwater footage of bed load transport due to wave action.

BUBBLES is an acronym for some combination of the words Bubbles the Underwater Undersea Blue Bathymetric Basal Buoyant Little Liquid Exploration Submersible or Submarine.

Bubble was previously deployed in a hot-tub and in Younger Lagoon, Santa Cruz, CA, as test sites. Recently Bubbles went swimming under the ice-covered Silver Lake near Kirkwood, CA. Due to the late season, we could not walk on the ice and the shore-based deployment was complicated by the shallow waters. Nevertheless, she again proved to be liquid-worthy, and spent some time swimming in the shallow waters with some fish.

Bubbles was built by Ken Mankoff and E. Lynne Harden.

Tags: fauna, ice, robots, Video

WISSARD Introduction

A video (and written) news segment on part of my PhD project:

Tags: Antarctica, ice, PhD, Research, robots, Video, WISSARD

It is Wet

These are most enjoyable and relaxing if played in HD full screen. Inspiration for BUBBLES. More on that later.

Tags: Research, Video