How I ended up searching for 3D satellite images covering Maratona dles Dolomites
Join my virtual ride in EO Browser
It all started when I ran into my friend the other day, whom I hadn’t seen in a while. After we talked, he told me about his future plans for the upcoming summer. I knew he cycled a lot, so it was no surprise when he mentioned that on July 4 he will be participating in the Maratona dles Dolomites — the world famous road bike amateur marathon in the Dolomites starting and finishing in Alta Badia, Italy. Yes, that’s the one with a length of 138 km and an elevation gain of 4230 m! As a recreational cyclist, this sounded fantastic to me. And I thought, if I can’t go on such an adventure myself, why not ride the route virtually. And while I’m at it, why not do it in EO Browser, which just got richer with this incredible 3D feature.
Why the Maratona dles Dolomites?
The biggest road cycling event in the Dolomites attracts with breathtaking views and impressive landscapes. Every year more riders want to take part than the marathon can hold. And to give you an idea of how desired it is among amateur cyclists, let me tell you a little about the history of participation.
The first edition took place in 1987 with 166 participants from Italy, Germany and Austria. The number increased from year to year and by the mid-1990s, more than 6,000 passionate cyclists were registered. In 2005, a pre-registration system with an entry draw had to be introduced allowing only 9,000 cyclists to participate in the marathon. Since 2014, there have been over 30,000 applications each year from would-be participants from all over the world hoping to be drawn. As last year’s event was canceled due to Covid-19 pandemic, this year everyone drawn from 2020 is invited to participate in the 34th edition on July 4, 2021.
Intrigued yet? Let’s dive in.
Exploring the Course in EO Browser
Searching for the location in EO Browser is super easy. Just type “Arabba” into the search, and voila. The area is immediately displayed. You can even import the marathon course. The GPX file provided on the official marathon web page just needs a little customization, which you can do in QGIS. If you want to try it out in EO Browser for yourself, I’ll share mine here. Import the kml file by using the “Polygon/Upload data” icon from the menu on the right.
Now all we have to do is find the most recent Sentinel-2 image, preferably without clouds. Open the calendar in the panel on the left and click through the images on the available dates. I usually use this little trick to find the best image — when the area of interest (AOI) is displayed, select the “Create timelapse animation” icon from the menu on the right. Set the search to last month and one image per day. This way you will see the available images already visualised on the left side. By scrolling down, you can easily decide which image fits best. The May 28, 2021 image seems to be cloudless, so let’s go with that one (image below, right).
To create a really nice impression, we should choose the appropriate visualisation. I used a simple but powerful script — the Highlight Optimized Natural Color script — that visualises the Earth in beautiful, natural colors, without burnt-out spots due to overexposure.
Inspecting the Snow Cover
What interests me most about the marathon are the parts of the course that might still have snow cover. That’s easy to see in Sentinel-2 images as displayed below.
On the image from May 28, 2021, it is obvious that the course is passing through snow covered areas. However, with the start of the marathon in two weeks, snow conditions can change quickly due to the current heat wave. To get an idea of what to expect, we can also look at the images from July 2020 when the snow was apparently completely gone (image below, right).
To visualize the snow cover (image above, left), I used the Snow Classifier visualization, which is available in EO Browser under the Snow and Glaciers theme. Its algorithm detects snow by classifying pixels based on different brightness and Normalized Difference Snow Index (NDSI) thresholds. Values that are classified as snow are displayed in bright, vivid blue. Test it yourself here.
Using the Terrain Viewer for Insight into the Climbs
The other interesting thing would be to see the hardest climbs that cyclists have to face. I would imagine that enjoying the view during the real ride would make the climb easier. But as much as it’s cool to ride virtually on the map and see the images almost in real time, seeing the mountains in a third dimension really makes it outstanding. And now just think of 3D views of satellite imagery in near real time, with applied different visualisations, that’s something.
For demonstration purposes, I’ll stick with the May 28, 2021 images. Clicking on the “3D Cube” icon in the menu to the right takes us to Terrain Viewer. Using the navigation tools on the left, we can already create beautiful visualisations. Although you don’t have to log in to EO Browser to use the 3D feature, I still recommend creating an account. It’s free for non-commercial use and allows you to use various features like saving your pins, creating time-lapses, etc.
The Famous Passo Giau
One of the toughest climbs in the marathon is the conquest of Passo Giau with 922m of elevation gain and the steepest gradient of 15 %.
“Sometimes referred to as the beauty and the beast, the Passo Giau is an extremely harsh and difficult test but is considered by many to be the most picturesque mountain pass in the Dolomites range. Standing at 2,236 metres above sea level the Giau boasts no fewer than 29 hairpin bends and is a relentless challenge of around 9% gradient over 10 kilometres.” — Epic Road Rides
My rides usually include some climbing, but it’s hard to imagine what this one would be like in reality. One can only hope the view is worth the effort and it helps participants get through it.
In EO Browser you can inspect all the available collections in 3D. So far I have used the free Sentinel-2 images because of their 10m resolution. But we don’t have to stop here. Let’s take a look at some high-resolution commercial data, such as Airbus SPOT.
Another neat trick that can be done seamlessly in Terrain Viewer is inspecting mountain shadows. You can simulate a position of the Sun to visualize shadow and light for any time of the year. Of course, I needed to check it out on the day of the marathon (simulation below).
There are many more features in EO Browser, but I’ll leave it to you to discover them yourself. The recommended links below will get you started easily. For individual features of Terrain Viewer, read Terrain Viewer in EO Browser: A Play of Light and Shadow blog post.
I hope you’ll enjoy your virtual journey as much as I enjoyed mine. As I sat in my chair behind the laptop, I got a slightly different insight into this amateur gran fondo event. It expands my imagination of what it might look like in real life. To get those real-life feelings, I still plan to do it myself someday — well, not the whole way at once, but maybe in a week or two. 🙂
Recommended links:
- Watch the EO Browser webinar to learn about other functionalities and how to use them.
- If you are interested in high-resolution data yourself, I recommend watching the Commercial Data in Sentinel Hub webinar.
- To highlight different events and phenomena on the Earth’s surface, choose from the available custom scripts or create your own. More about custom scripts is nicely explained here and here.
