We recently put together a prototype time enabled Web Mapping Service (WMS) with data from MODIS and VIIRS from 2015 to mid July 2016, and as an experiment, generated a short time lapse from it. The data in this video is a false color presentation using VIIRS “I” bands 3,2, and 1, a band combination we call “Landcover”. The video spans January 2015 to July 2016, and has some interesting natural processes in it - check out the ice movement, and the spring snow melt process. The affect the seasons have on the sensor’s coverage is also visible as the visible bands of VIIRS are only active over areas of the earth illuminated by the sun.
The above animation of VIIRS polar satellite imagery over interior Alaska south of the Brooks Range from the afternoon of 15 Jul 2016, shows how quickly
fires can spread in less then 4 hours. The three images used for this
animation were modified versions of the NaturalColor RGB, where the 2.3
um channel was assigned to the red color component (rather than 1.6 um),
0.86 um to green, and 0.64 um to blue. The 2.3 um has
similar ice and snow absorption characteristics as the 1.6 um, but with
more sensitivity to hot spots and fires. In this imagery the
red pixels are the hottest and most active fires with bluish colored
smoke blown eastward by strong west winds.
We recently had a question about getting GINA’s Best Data Layer (BDL) into BackCountry Navigator TOPO GPS
a navigation and topographic map viewing application for Android
smart phones and tablets. Since it is easy to do, and might be of interest to the wider
community, here is how to do it:
First, hit the
“Map Layers” button, then the “MORE MAP SOURCES”, followed by the
“CUSTOM MAP SOURCE”, and finally the “NEW CUSTOM MAP SOURCE” menu items.
This could give you a dialog like this:
Fill it out like above, hit “SAVE”, and it should now show up in the
“Map Sources” list, and should be usable just like any other map source
in Backcountry Navigator, including using its tools for building an
More detailed instructions can be found on Backcountry Navigator’s help site.
Other mapping applications that allow custom map sources work similarly, and this process will work for any of GINA’s other web mapping tile sets.
PS: The “Max Zoom” setting affects resolution of the data - larger zoom levels mean more detail, but that comes at the cost of space. A value of 16 works out to be about 2.4 meters per pixel, 19 to be 1/3 of a meter per pixel.
New elevation color-relief hill shade layers.
Over the past few weeks, fellow GINA GIS analyst Mitch Slife and myself have been busy in the GIS lab cooking up something special. We have been working on creating a new set of shaded color-relief images. Inspired by an old post by Tim Sutton on linfiniti.com, we focused on a fully command line workflow for generating geospatial masterpieces without restrictive obstacles like graphical user interfaces. This fully command line approach will allow us to scale this new hill shading to a variety of other elevation datasets in our archives.
We will be following this post up with links to the new datasets in our Web Mapping Services (WMS) and catalog system so those interested can start using these hill shades in their day-to-day GIS visualization activities.
A plane creates a neat artifact in statewide orthomosaic map.
The 2010-2015 statewide orthomosaic map was created using satellite imagery, SPOT5 satellite specifically. The SPOT5 satellite has two imagery sensors, 10m resolution multispectral sensor that provides color information and a higher 2.5m panchromatic sensor that provides higher resolution detail in greyscale. These two sets of sensor data are combined to create the SDMI orthomosaic map product. Think of the two sensors as two different cameras taking pictures from the satellite in space. The images are not captured close in time but not exactly the same time. This creates a neat effect that can be seen in fast moving objects like airplanes.
The images here show the effect of having a plane being captured first by the high resolution, 2.5m, panchromatic sensor (greyscale) and then being captured by the lower resolution multispectral (color) camera. The plane has flown forward and the spacecraft has orbited farther down it’s earth orbit changing the look angle of the camera.
More details about the statewide orthomosaic map and the Alaska mapping efforts can be found at the following websites:
We have recently added USGS Historical topographic maps for the State of Alaska to our EPSCoR Web Mapping Service (WMS) at http://ogc.gina.alaska.edu/epscor . These maps provide an interesting look at how Alaska has changed over time. Questions or comments? Email us at firstname.lastname@example.org .