Hurricane Harvey gif 8/21-8/31

Uh, this is awesome

Hurricane Harvey stirring up the Gulf of Mexico

Here's an interesting image of Hurricane Harvey framed by the coast of the Gulf of Mexico. Harvey is supposed to make landfall tomorrow and will be the strongest storm to hit Texas in 12 years. This image was taken from the satellite Terra, which together with sister satellite Aqua collects daily imagery of the earth at 250m resolution using MODIS sensors.

Hurricane Harvey 8/24/2017

Eclipse 2017

Hope you enjoyed the eclipse!
Here's my shot during totality-

Here's the traffic across the US after the eclipse, notice any patterns?

Disneyland Star Wars Land

I went to Disneyland earlier this year and Tomorrowland was packed the entire time. Star Tours is my favorite ride and I haven't been on the new one yet, but I never got to see it since the line was so long. All the other rides had low times when you could sneak in and not wait too long, but Star Tours was 2 hour wait every time we checked (By the way, the Disneyland app is amazing, wait times for each ride, maps for bathrooms and food, it's a game changer). I was dissapointed I didn't get to see Star Tours, but I am looking forward to the new Star Wars land being developed on the NW side. Here is some aerial imagery from 2016 to show you what they are up to:

Disneyland Feb 2016 - Google Earth

Disneyland October 2016 - Google Earth

Clearly a lot of resources are being put into the new Star Wars Land, which is great, because all those fans will have somewhere to wait in line besides Tomorrowland and maybe I can finally see Star Tours!

Since this is a remote sensing blog let's do some imagery analysis on these images and talk about it. There is obviously a lot of change going on between these images, let's try and get an idea of how much and where. There are many methods for change detection, but the most simple (and probably my favorite) is an image calculator function that subtracts each image from each other.  Each pixel has a numerical value that represents each color. Similar values will show similar colors. If we subtract each pixel value from each image our resulting image will show where these images differ and by how much. 

The result:

Disneyland Change Detection Image

Now we can quantify where there is change. Black and white show areas with major change while grey shows areas that are mostly the same. Quickly we can see that cars on the streets were not in the same spot on both images, which we would expect. Also we can see outlines of buildings being highlighted, and when you look closely you'll be able to see those outlines come from different amounts of shadows on each image since the imagery was taken during different times of day with different sun angles. One fun remote sensing exercise would be to identify the time of year and day by measuring the shadows.
Obviously the most change comes from the large black area in the NW, which is where Star Wars Land is being put in. Here is another image that colors the values differently and helps to bring out the change:

Disneyland Change Detection Raster. Blue=little change Red=major change

We can see that buildings and vegetation were removed, which are shown as red. If we wanted to get really detailed we could summarize the exact area that has changed, something that mines and construction companies find to be useful. 

Pretty fun stuff, looking forward to Star Wars land in 2019!

Here is a parting google image with some buildings on Disneyland rendered in 3D you may enjoy (I guess they still need to get some Revit interns on creating the rest of the park...)