Thursday, December 7, 2017

Image of the Day November 22

I thought this was an interesting image. At first I assumed this was a village that may have been flooded. At first glance there appears to be buildings underwater to me. However, when I looked into it, it turns out this is a fishing village built on stilts. This is the Ko Panyi Village in Thailand. It was originally built by Indonesian fisherman back in the 18th century. You can see white spots on the water which I assume are boats creating wakes as there is little other way to move from place to place in an area like this other than boat. This is a very old village that has withstood the test of time. It makes me wonder why it was built. There is land surrounding this village that it may have been able to build on way back when. There even appears to be a building on the right side of the river on the shore as well as one above the village. What could have happened that the idea of building a village on stilts was better than building on the land?

Monday, December 4, 2017

Image of the Day: December 5th, 2017

This image is of waterfowl, mostly ducks, along the Mississippi River in western Wisconsin. The Wisconsin Department of Natural Resources uses aerial surveys to estimate population numbers for many species, including wolves and deer. In 2013, the Wisconsin DNR turned to aerial imaging and surveying to estimate deer populations in the Chronic Wasting Disease Management Zone, a section of southwestern and south-central Wisconsin where the disease had been found. CWD is a deer prion disease, much like Mad Cow Disease, that is highly infectious in regions with high deer populations. To prevent the spread of the disease, the DNR sought to drastically reduce the number of deer in the afflicted areas by issuing more hunting licenses and hiring sharpshooters. Before setting harvest quotas, an accurate assessment of the deer population was needed, Normally, game managers use roadside surveys and demographic information from deer harvests to create life tables that can be used to estimate herd size. However, these data sources have implicit bias, Using aerial surveys allowed game managers to create a more detailed and accurate assessment of deer populations. Surveys had to be conducted when the ground was entirely covered with snow, otherwise the dark-colored deer would be nearly impossible to spot. Predetermined survey tracts were chosen, and flown by both fixed-wing aircraft and helicopters. In other studies, drones have been used. Unfortunately, the CWD containment was largely ineffective, and CWD remains a threat to Wisconsin's deer population. This tactic of aerial sensing for wildlife is used extensively around the world to refine population estimates. I found examples of it being used to survey moose, manatee, ostrich, alligator, elephant, rhinoceros, seals, and nesting shorebirds, as well as waterfowl and deer, of course.

Wednesday, November 29, 2017

Image of the day, November 29, 2017

This image shows an application of active sonar remote sensing to map fish populations and habitat. Sonar involves the active emission of sound pulses, which are reflected by objects that have a different density than the surrounding water. In this application, the sound wave is reflected off of the air-filled swim bladder inside the fish (the white arrow in the center of the image points to a school of fish), and the strength of the echo (represented by color) increases with the size of the fish. The arrow on the right points to the seafloor, which also reflects sonar. This application of sonar is commonly used by researchers and commercial fisheries, and also by members of the public in portable fishfinders, which are used by anglers to locate good fishing spots.

Tuesday, November 28, 2017

A Remote Sensing Imagery Search Engine in the Age of the Remote Sensing Boom

For this image, the significance more so lies in the source of the image than the image itself.  It is a snapshot of the power that this new search engine application for aerial and satellite imagery possesses.  This particular photo is a Landsat satellite photo of pivot irrigation fields.  The photo is pulled from the application itself where the user is able filter between aerial or Landsat imagery and either sift through popular search filters such as pivot irrigation or suburbs or input one of their own by selecting their own sample location.  In choosing their own sample location, the user is supplied with a long list of like features throughout the tileset as determined by a likeness/likelihood algorithm.  The application is becoming increasingly important in a day and age when aerial and satellite imagery is constant and flowing.  Currently my supervisor at the State Cartographer's Office is using the application to attempt to find all baseball fields throughout southern Wisconsin that a potential client could market to based on his findings.  This would be tedious by any other means, but with the application he can select a single baseball field in one area and use the accompanying mini map to find all baseball fields in southern Wisconsin based on likeness.  Linked below is an article that gives context to the importance of the application and also a link to an FAQ provided by the lab behind the application's development that provides insight into how the application functions.

Thursday, November 23, 2017

Image of the Day 11/23

This image is of Bardarbunga Volcano is Iceland. This image specifically is of a lava field of this volcano that is active. There is a pool of magma in the right hand side of the image as well. This was taken using the German satellite TerraSAR-X and the image shows an area of 30km x 50km. This image is especially interesting because this specific volcano has was active in November and was on watch for an eruption. I could not find a photo of the most recent volcanic activity and this image is from 2015.


Sunday, November 19, 2017

Image of the Day 11/21

Landsat Images showing Ice Scours in the Caspian Sea

Image 1: This is a Landsat 8 image of the Caspian sea acquired on April 16th, 2016. The image clearly shows a strange seabed scouring phenomena in the region of Tyuleni Archipelago (the light colored lines that break up the darker green vegetation visible on the seabed). One thing that makes them curious is that groups of scours are often parallel to each other and appear to be formed by objects traveling in the same direction. The initial cause of these features was confusing to analysts, one possible proposal is that they were human in origin - the result of seafloor trawling. It was not until this image was compared to the second image, taken in January, that the origin of the scours was identified as gouging caused by sea ice starting to break up.

Image 2: A Landsat 8 image that shows the same region in winter. In the northeastern portion of the image the ice is starting to break up and it is possible to see the scour marks which occur behind the leading edge of shrinking ice floes. This occurs because the Caspian sea is very shallow and the sea ice that develops there is relatively warm and thin. This means the ice pieces are easily moved by wind and currents and are often pushed together, causing some of them to tilt, forming structures called “hummocks.” In the shallow water, the “keels” of these hummocks can become wedged in the sediment, causing scouring as the ice bed is moved. Once the ice melts, only the scour marks persist in the spring and summer, creating the pattern seen in the first image. The parallel nature of groups of lines in the first image can be explained by several ice pieces all being dragged along a similar path by the same wind/current.