A very useful tool ... Offline USGS topo maps on your phone

http://feedly.com/k/16i8YZ4

The effect of error on cultural transmission | Open Agent Based Modeling Consortium

The effect of error on cultural transmission | Open Agent Based Modeling Consortium

The Dangers of the Recent "Anything Goes" Trend in Archaeology...

 

Last night, the IgNobles were announced:

ARCHAEOLOGY PRIZE Brian Crandall and Peter Stahl, for parboiling a dead shrew, and then swallowing the shrew without chewing, and then carefully examining everything excreted during subsequent days — all so they could see which bones would dissolve inside the human digestive system, and which bones would not.

REFERENCE: “Human Digestive Effects on a Micromammalian Skeleton,” Peter W. Stahl and Brian D. Crandall, Journal of Archaeological Science, vol. 22, November 1995, pp. 789–97.

Mobius ActionCam as a Near Infrared Camera

I have been working on modifying cameras to allow us to be able to take remote photos using our various platforms (quadcopters, fixed wing, etc) in the near-infrared. Doing so gives us an ability to generate NDVI images and study differences in vegetation health (and thus potentially archaeological features ala crop marks, etc.). The criteria we've had is that the cameras have to be (1) light and ideally (2) cheap. We know we can do this for Canon cameras and get good results.  What is required is taking the camera apart and removing the IR filter that is ordinarily placed in front of the CMOS or CCD sensor.  Some cameras are easier than others to modify in this way.  I have done this for a Canon A380 and for a couple of GoPro Hero (Naked and 2). We also sent one of our Ricoh GR III cameras to a commercial service to have this done (this cost a couple of hundred bucks).

With these point-and-shoot cameras there are some drawbacks.  First, they are mechanical and have parts in them that are easy to mess up once you take the cameras apart. Ive screwed up one or two of our cheaper Canon's this way -- once some spring get sprung they can be nearly impossible to reassemble.  Second, they are heavier than they need to be. With remote sensing we are basically focusing on infinity and we want a relatively wide angle view. As a result, we don't need all the focusing mechanics or any optical zooming and what not. This just complicates the entire camera and weighs it down.  Third, they somewhat expensive. Once you start opening up cameras and yanking out parts, it is preferable to have the cameras cost well under $100 each.

Iam Bouret, one of our fantastic collaborators on our NSF REU program (http://www.csulb.edu/geography/nsf-reu/) suggested that we look into the Mobius ActionCam as a possible candidate for our NIR camera. This camera costs about $70 has a 5MP sensor, is configurable via open firmware and software, is solid-state and easy to take apart.  You can read all about the camera here: http://www.rcgroups.com/forums/showthread.php?t=1904559.  A windows-based GUI allows the camera to be customized (http://www.mytempfiles.info/mobius/index.html) Using this interface one can set the resolution of the images, the default modes, and the intervalometer.  

Taking the camera apart was very easy. If you follow the guide on the http://www.mytempfiles.info/mobius/index.html website you can follow along. Basically there are a couple of screws holding the case together and the lens is removable by detaching a ribbon cable from the main board. Once you do that you can open the back of the lens and remove the IR filter (its immediately above the CMOS sensor). Then the entire thing goes back together again in the opposite order. There are thankfully no springs or mechanical bits to make the job messy - it really is about a 10 minute job. 

Once you remove the IR filter you have a camera that records images that include a portion of the near-infrared spectrum.  This is great but what you are doing is simply allowing more light in the camera. The results are still split into the RGB bands - there are just additional wavelengths present (this is why the IR filter is used - to just show the visible spectrum).  To isolate the NIR you need add a filter so that you get the near IR to use one of the bands.  In black and white film photography this is usually done with a yellow filter that cuts out the bus and thus shifts the spectrum up in wavelength so that you get nearIR (N), red (R ) and green (G).  An alternative that seems to be preferable for digital images is to use a blue filter to eliminate the red.  What you get then is a file that records just the NGB (the red is removed). Ideally one would take simultaneous shots with a regular color camera to provide 4-band images (NRGB) but that requires 2 cameras and a way of registering the two sets of images. 

Jeffrey Warren of Infragram (http://infragram.org/) project on Public Lab sent me a piece of their "infrablue" filter to use with the NIR modified camera. This filter seems to be well suited for removing the red while allowing the near IR band to be collected by the CMOS sensor.  Here is a sample NIR image (compare to the RGB).

Finally, I ran the NIR image through the Infragram sandbox to generate an NDVI. The results look pretty good, but Ill have to check how the spectra to see if we are getting good separation of the bands.  Apparently the Infragram folks have found that some of the cheap-o CMOS based camera sensors are set up in a way in which there is a lot of blue leaking into the NIR band. Obviously this will screw the image up for analytic purposes. From what I understand this is caused in some cases by the fact that a Bayer RGB filter is not always used to separate the light into 3 bands. So there is a need to search for a cheap camera that still has good properties in terms of splitting the bands.  

Given these results, though, it appears that the Mobius Action cam might do the trick. Ill be interested to hear what the folks at the Infragram project think. 

 

 

 

 

Dogs!

American Dog Breeds Came From Asia During Pre-Columbian Times, DNA Study Suggests

http://rockmelt.com/m/-3v5nXJA

Project ideas

From this summer, I've put together a list of possible projects that could be tackled by ambitious (and relatively tech savvy) students for an MA or honor thesis. 

• Mapping and integrating vertical imaging of surfaces with horizontal imaging (I.e., "greg's" project). This is largely a matter of figuring out how to best integrate the different datasets. Greg focused on the "images" and found they couldn't be matched — which isn't a surprise given the way each program deals with them. But the data are different — the XYZ coordinates. Those should be integrate-able. The images are a separate matter.
• Detecting and mapping cave features with TIR, NIR and VIS imagery. Jeanette didn't integrate the multiple sources of imagery into a single classification so couldn't get a good product. Im not sure why she didn’t do that other than "not enough time." But this would be the way to go.
• Multispectral camera (V1.0) use in mapping vegetation. This would be a project that would have a student work on the existing MS camera to map vegetation in an area of interest (e.g., Palo Verde or somewhere else). The current camera is functional and Im working on it to reduce the weight. This way it could be flown with the quadcopters — which means that students can do their own data collect. They would need to be wiling to:  learn some python to process the data, learn to futz with the electronics, have an area interest. But it would be a good project that builds on what we have already and the work that the Montana State University folks did (as ours is a variant of their camera but with more bands). 
• Multispectral camera (V2.0) The next version of the MS camera is going to be Raspberry Pi based. It will build on the concepts of V1 but have a lot more onboard processing and much higher resolution (and be lighter). What I envision is a camera that has 1 Rpi for each band with a single Rpi acting as controller and data integrator.  The cameras will be the tiny 5.0 megapixel cameras. This would be a great MA project I think. The goal will be to improve on the original  design and make it more modular with better on-board processing (such as automatically producing NDVIs). The student would need to learn python, GDAL, linux and be willing to learn about how the electronics work (but its all fairly simple). 
• Thermal camera image integration with UAVs — We need someone to take on figuring out how to take thermal imagery with the camera and integrate this into a geospatially referenced mosaic. The project would be electronic, programming, UAVs, and could focus on studying groundwater discharge along the coast of PV (or some other handy area). 
• Thermal camera mapping of archaeological features. Measuring differences in temperature due to buried rock features has been shown to be a great way to detect archaeology. No one has done this with a platform as small and mobile as what we have. Someone needs to figure out the best procedure for doing this, design a good test study, map some existing features (could do this in Mississippi, rapa nui, guatemala). 
• Thermal camera detection of artifact composition – Paul Buck (DRI) has demonstrated that long wave sensing can be useful for doing sub pixel mapping of varying density of artifacts. Id like to see if we can use this approach in a micro artifact identification capacity. This would combine image processing (perhaps via ImageJ) and image classification (perhaps via eCognition) to count artifact classes automatically. We would use the thermal camera in a microscope arrangement… 
• Temper identification in prehistoric ceramics: similar to above but examining how TIR can be used to quantify the composition of ceramics from image analysis alone. 
• Image analysis for mapping surface archaeological features with X100 We would fly X100 over landscape to map the surface in terms of topography, archaeology, hydrology. We need someone to work on extracting archaeological distributions from the imagery (would need to figure out best sets of filters/wavelengths, techniques in eCognition and so on).
• Constructing the ideal app for doing aerial photograph connected with photoscan. Someone needs to figure out the timing, georeferencing and processing. This could be a commercial application if done well. The person would need to be willing to learn some programming (well, quite a bit of programming).

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.