For several years now, I’ve been using Esri’s ChangeMatters site to help students get an early taste of the power of remote sensing. They get excited about the ways in which we can use the long history of satellite imagery to do science, and, let’s face it, look at cool pictures of the earth.
For those who haven’t tried it, it looks like this:
You simply choose a date range, and an image type (IR, true color, etc.), and watch the magic happen. The third pane displays vegetation change. You can move the map in any of the panels, and the other two update. My students are tasked with finding a place of interest to them, noting the changes, and then doing a little digging to find out what event(s) caused the change they see.
So this week, I trot out my trusty assignment, and students immediately let me know that the site is redirecting them to something else that doesn’t seem to do what I’m asking them to do.
The original link, changematters.esri.com, now redirects to a page with some beautiful imagery and a swanky new interface. Visitors are encouraged to “Try it live”, and that button takes you to a page with four options, Landsat Viewer, Landsat Explorer, Arctic Landsat Viewer and Antarctic Landsat Viewer, which are bewildering to the geospatial novice.
For my purposes, since I wanted students to look at images side by side, I chose the Landsat Explorer option. It features the Swipe interface, which I didn’t see in the Viewer (if I missed it, apologies, but I was trying to quickly push out new instructions for my class). Here’s the quick and dirty update I cobbled together for my students; hopefully it will help some of you who have suddenly discovered you need to update your assignments as well.
If you are using the old link, and get redirected, click Try it live, then select Landsat Explorer.
The new link is http://landsatexplorer.esri.com/. (If it takes you to a story map, scroll all the way to the end until the toolbar pops up on the left.)
- Enter a place you’d like to view in the upper left.
- On the tools on the left, select the wrench. Set the rendering to Color Infrared.
- Next, click the clock to set a timeline. Set the date you want for the first image, then click the little blue arrow in the upper right of that box. Set the date for the second image.
- Right below the clock button is the Swipe tool (looks a bit like the elevator door symbol). Click that and you’ll get a divider in the middle of the screen that you can swipe back and forth and look at the changes – you’ll see the first image you picked
- If you want to look at different bands, set the renderer (wrench tool) to the bands you’d like to see, then reset the timeline.
Unfortunately, this site seems to have a less complete image set, so you may have to do a little exploring to find a place that has imagery for multiple dates. If you’re not finding stuff, try setting the cloud filter a little higher (not too high, or you’ll get nothing but clouds!).
Spend some time exploring, then continue on with the activity prompt.