NOVA special: Easter Island

The NOVA documentary has finally aired on PBS!  If you missed the showing on November 7th, check out the full movie online.

Watch Mystery of Easter Island on PBS. See more from NOVA.

The Navigational Blackbox

As Im getting ready for the Nat Geo talk this week, Im also trying to anticipate field work on Kauai that is beginning Monday (but I won't arrive until next Saturday). One bit of electronics that I've always wanted is a data logger that records location, orient

ation, tilt, yaw, bearing, and magnetic readings in a precise and rapid way. This would be useful, for example, for logging images of taken from a blimp so that they can be better corrected and georeferenced.  More importantly, a data logger such as this would be ideal for the GPR -- one could record the antenna angle and orientation relative to the ground so that the data can then be correctly modeled to take into consideration the direction the antenna is pointed.  Lacking this information, one assumes the antenna is pointed straight down -- but we known when we go across any terrain that this isn't true. Even when the terrain is relatively flat, there are often bushes and other kinds of things that one has to go over and that can create artifacts in the data. Dean Goodman's software GPR-slice software can make use of topographic information to help correct for terrain changes -- but this is only going to handle very large changes (such as surveying over a mound or down a hill).  What we really need is a little box that sits on the antenna and that records the position and orientation as the antenna moves.  And if we can also collect magnetometry data - boom - we have an instant mag map

The way to do this, I think, is with an arduino board and some sensors. I got an Arduino Mega 2560 board from Adafruit.  I then added a SparkFun triple axis magnetometer, 6 degrees of freedom accelerometer, an OpenLog data logger and the adafruit ultimate GPS.  All for about $150.00.   

I started using the incredibly cool Fritzing tool (http://fritzing.org/) which provides means for creating wiring diagrams and electronics.  The tool has many of the breakout parts for the arduino ready for cutting and pasting and the user libraries are huge.  What is particularly cool is that one can create an electronic device and then have it manufactured. I guess they aggregate bunches of board designs together and then get them printed en mass as some German factory. Cost is per board and goes down the more one orders.  So you can do some DIY stuff to try things out and if it works well, you could mass produce the boards to your own specs. 

Following the excellent wiring diagrams on Adafruit and SparkFun, I created a device that put all these pieces together (below). My wiring isn't particularly well organized but I was more interested in tracking the places to connect the wires for the multiple devices.

 

This is actually my second device for arduino. The first was a simple one built on a Arduino Uno board. All it does right now is runs a program that sends 5 volts in a particular pattern of timing to one of the output pins. Two mini-USB cords are connected to this pin (and ground) and plug into two digital cameras (Ricoh GR III).  One of the cameras has been modified to shoot near IR photos (and has a yellow filter). Together they provide a poor-man's four band (R,G,B, + NIR) camera.  The Arduino device triggers both cameras every 3 seconds -- this way we get synchronized shots that can be then be merged to form a single 4-band image. It works quite well - runs off of 3 AA batteries, is light weight and hangs from the camera mount that is suspended from our blimp or kite (or hexacopter).  I might add a GPS logger to it as well so that we can use it to record locations for each photo pair - that wouldn't be hard or very expensive. I bought an SD card logger ($20) for the Uno and wired it up. All I need is to get another Adafruit Ultimate GPS breakout (for $25). 

I should mention that the Adafruit Ultimate GPS is pretty sweet. It has a built in logger (64K), can track 66 satellites at a time and do 15 measurements a second. Plenty for the kinds of applications we have...

 

Kauai Geospatial Field School

We've been working all week to get the NSF-REU program off the ground. Students arrived in Long Beach on the 17th and over this past week we have been introducing them to research, geospatial analysis, image analysis, object based classification, structure from motion, XRF, multispectral analysis and so on. Its been quite a week of lecture and exercises.  Below is one of the images we are working with to attempt to extract the patterns of prehistoric agricultural practices -- visible faintly as geometric patterns in the crops on this southern chunk of Kauai.  

 

The students come from a wide range of locations and have a diverse background. We have asked them to write a daily blog of their activities so you can follow along by going to:  http://www.csulb.edu/geography/nsf-reu/  The blogs are linked on the left hand side of the page.  These should be come even more entertaining this week as we depart for Kauai early tomorrow morning and begin field work!

 

Science and Feynman

This is linked on NPR right now but few folks can boil down the essence of science to a short set of clear ideas like Richard Feynman.
Check it out here.

In general we look for a new law by the following process. First we guess it. Then we compute the consequences of the guess to see what would be implied if this law that we guessed is right. Then we compare the result of the computation to nature, with experiment or experience, compare it directly with observation, to see if it works. If it disagrees with experiment it is wrong. In that simple statement is the key to science. It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is – if it disagrees with experiment it is wrong. That is all there is to it.

From 1964:

The remark which I read somewhere, that science is all right as long as it doesn't attack religion, was the clue I needed to understand the problem. As long as it doesn't attack religion it need not be paid attention to and nobody has to learn anything. So it can be cut off from society except for its applications, and thus be isolated. And then we have this terrible struggle to try to explain things to people who have no reason to want to know. But if they want to defend their own point of view, they will have to learn what yours is a little bit. So I suggest, maybe correctly and perhaps wrongly, that we are too polite.

Anthropology Major

 

One of the most common complaints that I hear about our major (from faculty and students) is that it doesn't train students to do anything. Yes, this goes against the "4-field/allow no specialization" mantra, but it is stated again and again by our most ambitious, talented and smart students.  The reasons for these complaints are clear: we fail to offer a coherent set of classes that provide in-depth training (laboratory and field as well as conceptual/critical) in the areas of the discipline that require them (and for which there is abundant demand) and we have gotten rid of the classes that used to make us a notable department.  Now with the exception of just a few classes, we offer a fairly useless major – like most anthropology departments.  

 

The reality of where we stand is made clear through this NY Time Op Ed piece and this recent AP study. Those students who get majors who are not trained to do anything (I.e., "4 field") are the least likely to get jobs.  The anecdotal and statistical evidence is consistent.  Although a taboo topic in faculty meetings, this is a serious problem that should be addressed one way or the other. Solutions should be implemented: — I.e., bringing back a range of in-depth courses in field, lab and analysis in specific aspects of sub disciplines with pre-requisites and specialization. Sadly, in our department at least it doesn't appear that such a discussion will be allowed to take place.  Tragicomedy for our students at their own expense….

NSF-REU 2012: Geospatial Research on Kauai

http://www.csulb.edu/colleges/cla/departments/geography/nsf-reu/

Anthropology and Geography undergraduates -- as well as others interested in the study of landscapes-- may be interested in a new summer field program on geospatial research and mapping (GRAM) that will take place at the National Tropical Botanical Gardens (NTBG) on Kauai this summer.  This field research program is a joint effort between faculty in the Department of Geography and Anthropology at CSULB and is focused on the use of cutting edge geospatial techniques (e.g., satellite and aerial imagery, the use of UAVs, geographic information systems, spectral analyses, topography generation, landscape analyses, near surface remote sensing, etc.  The research being undertaken by GRAM includes the study of prehistoric landscapes as well as contemporary resources and environments. A website is now operational (http://www.csulb.edu/colleges/cla/departments/geography/nsf-reu/)  that describes the program and includes an application form, details about the the NTBG and so on. This field training course is funded for 3 years via the National Science Foundation (NSF) under their Research Experience for Undergraduates (REU) program.

This year's GRAM project will take place June 11 to July 7 and include training in Long Beach and the National Tropical Botanical Gardens in Kauai. The NSF-REU program provides funding for student to cover travel, housing, tuition costs as well as a small stipend. Applications are competitive and open to undergraduates across the country. Note that students must be enrolled as undergraduates in order to meet the requirements of the REU program -- graduated seniors are not eligible per NSF rules.

For information about the program, the application, schedule, etc, please see:

http://www.csulb.edu/colleges/cla/departments/geography/nsf-reu/

or contact me.

Cheers,

CPL

Carl Lipo, Professor
Department of Anthropology and IIRMES
California State University Long Beach
1250 Bellflower Blvd.
Long Beach, CA  90840

Ph: 562-985-2393
Fx: 562-985-5179
Email:  clipo@csulb.edu
Blog:  http://www.evobeach.com
Web:  http://www.lipolab.org

Pocket Magnetometer?: A Holiday Break Experiment

I've often wondered whether the magnetometer built into the iPhone is sensitive enough to be used as a remote sensing device.  At CSULB we use a Geometric 858 cesium vapor magnetometer to map subsurface deposits.  This ca. $25K instrument provides very fast and high precision measurements of the earth's magnetic field.  Collecting 10 readings a second, the 858 is capable of measuring differences as small as 0.008 nanoteslas (gammas).  While this precision is fantastic, often the variability we are interested in (e.g., hearths, organic deposits, etc) varies substantially more than that from the background magnetic field.  When mapping a large area, it isn't uncommon to see lots of noisy measurements at 1-10s of nanoteslas with features of interest showing variation in the 100s of nanoteslas. Of course, one's ability to measure differences in subsurface magnetics depends largely on the degree of variability of the background. The noisier the background (i.e., larger the highs and lows), the bigger the signal must be from the feature of interest. Using a gradiometer (i.e., two sensors and subtracting the difference) greatly aids in filtering out noise -- more on that in a bit.

The iPhone's magnetometer is reported to be sensitive to changes as small as 0.1 microteslas.  That is 100 nanoteslas (gammas). This means that the differences detected have to be pretty large, but also that it is not too far off from where we want to be.  It can report values as fast as once per 0.01 seconds.

To check out how the iPhone might work, I wrote a quick app that polls the magnetometer.  For simplicity, I also had it poll the GPS for locational information. I say simplicity since this has a number of consequences.  One the one hand one gets X and Y locations for each magnetic value.  One the other hand, the rate of update is slowed to one reading per second - which seems to be about the limit of the iPhone for producing locational values. I'll have to check on this though.  Using the iPhone GPS also introduces locational error since the phone is a pretty basic GPS w/ 2-5 meter error (at least).  The app creates a text file with the three values -- X, Y, and mag.  Oh, and for the mag value, I calculated the overall magnitude of the field at each position.  This is because the built in magnetometer actually returns values in 3 dimensions (x,y,z) which is cool, but means that small shifts in the orientation of the iPhone will be detected.  To calculate the overall magnitude, I simply stored the  sqr(x^2 + y^2 + z^2).

A more elaborate app would probably include a couple of features -- first, it would have one define transects in some systematic way and then have a way of marking the beginning and ending of the transects in the file.  Second there would be some way of placing markers in the file for indicating intervals.  These two bits of data would be useful for stretching the values for each transect in an fashion that would best represent the survey.  This might even not use GPS at all (though one would then have to layout and map a grid, and then georeference that later).  One might also make use of 2 iPhones to create a gradiometer -- or even take an Arduino Uno ($50) and 2 magnetometer sensors (maybe something like this or http://microcontrollershop.com/product_info.php?products_id=4565 -- $15/each) to construct a mini-gradiometer(space the sensors about 1 meter apart with one close to the ground and one at waist level).   For kicks, maybe add a gps -- http://microcontrollershop.com/product_info.php?products_id=2768 ($60) at the same time and some kind of analog input for adding markers ) Add this for data logging:http://microcontrollershop.com/product_info.php?products_id=4526 ($25.00). One could make a pretty slick little measurement device and data logger for doing mag/gradiometer surveys for under $200. Add in additional mag sensors to create an "array" and one can get pretty serious.

But there is still a concern -- is the basic magnetometer sensitive enough to changes subsurface changes in composition?  With my quick iPhone app, I did a quick survey in the park across from my house. This was a number of transects (up and down) that were done perpendicular to the curb of the circular park.  I uploaded the data into Surfer to and then added the file into QGIS so I could have the output georeferenced over a satellite image.  Below is what I ended up with.  In the image dark colors are low magnetic values, white colors are higher values.

 

Pros:

-- It was certainly fast and cheap. The quick app worked with minimal pain.

-- The data definitely characterizes the curb edge of the park.

-- There may be other subsurface structures as apparent from the data.

 

Cons:

-- The one-second update rate for the location is a bit slow for getting mag points. A dedicated gps card (as described above) would be a huge advantage as these cards can usually produce location at 5-20Hz.  With the mag producing values at 0.01 seconds, you would have far more dense data to produce a map.

-- I'm not sure why the other structures are apparent in the data.  These are possibly due to subsurface pipes and whatnot. The lack of even data points across the survey area, however, is probably most likely to blame.  I didn't mark out my transects ahead of time (which is always a good idea) so I know I didn't walk in straight parallel lines.  An interface on the app might provide "steering" to keep on on a transect - that would help.  Also, having markers would enable one to ensure the data are distributed correctly across each transect (provided motion was constant).  Combining both the gps data (direction, speed, location) with some kind of marker system for end/middle/beginning of lines would probably provide a low-cost but reasonably reliable solution.

GPS Precision

It would be great to be able to post-process the GPS data to correct them for atmospheric error and reduce the uncertainty. There have been some successes in doing post processing of consumer grade gps units.  Most notably, garmin gps units can be coaxed into producing pseudo-range and carrier phase data (see:http://www.fig.net/pub/cairo/papers/ts_03/ts03_02_schwieger_glaser.pdf http://gpsinformation.info/harris/gpspostprocessing.html http://www.gps-forums.net/impressive-resolution-garmin-etrex-gps-using-gringo-t35448.html). The 12-Channel Lassen IQ receiver (http://www.sparkfun.com/products/163) ($50.00) might be just the thing as it produces RTCM output in addition to standard protocols. Some thing to look into, for certain. Additional discussion of the Lassen IQ is here: http://forum.sparkfun.com/viewtopic.php?t=809. Actually, that should be possible according to the reference manual. http://www.sparkfun.com/datasheets/GPS/Lassen%20iQ_Reference%20Manual.pdf.  The TSIP protocol can be set to output raw measurements and raw pseudo ranges (though the default is off). See page 112 for the TSIP protocol. This could mean a really cheap post-processing capable GPS!  Sweet.

This project - Kinematic -- has done much of the research -- but seems to be dead. http://web.archive.org/web/20090202200458/http://www.precision-gps.org/ It suggests that the Lassen is capable of producing 20-50cm precision since it lacks carrier wave information. Hell, that would be awesome.