Showing posts with label aerial photography. Show all posts
Showing posts with label aerial photography. Show all posts

Thursday, June 7, 2018

Perspective of a facade from above

One of the systematic issues that nighttime imagery has to deal with is the fact the orientation of lights and their position relative to buildings and other objects affects whether they can be seen from above. Take for example, these two images of the area near Berlin's Zoologischer Garten station.

This work by Alejandro Sanchez de Miguel, Christopher Kyba, and Freie Universität Berlin
is licensed under a Creative Commons Attribution 4.0 International License.

When our aircraft was north of the area, it was able to see north facing facades that were illuminated. These illuminated facades are invisible, however, when viewed from the South. This means that when satellites take images of the Earth at night, the "answer" for how bright a city is depends to some extent on where the satellite was when it took the image.

Update (August 5, 2019)

My student Jacqueline Coesfeld wrote a paper that uses these images, and considers how this effect (and others) result in variations in how much light is seen by satellites from night to night. The paper is Open Access, so check it out!

Sunday, November 1, 2015

Photos of Berlin at night

On Saturday I flew over Berlin and took a number of photos. I posted them to twitter, and all of them are collected below:






























If you liked the photos, please share your favorites along with this post on twitter and facebook!

Check out these 15 photos of Berlin at night from 9,500 feet up! http://lossofthenight.blogspot.de/2015/11/photos-of-berlin-at-night.html

Posted by Verlust der Nacht - Loss of the Night on Sunday, November 1, 2015


Sunday, October 26, 2014

Photos from our light over Linz, Austria

Tonight we did a measurement flight over the cities of Linz and Wels in Austria. The goal is to make a mosaic image of these ares of Land Oberöstereich, in order to understand the region's waste light emission. We have done something very similar for Berlin.

I wanted to share a few photos from tonight's flight:













The project is a research collaboration between Freie Universität Berlin, Universität Wien, and Land Oberöstereich. The flight costs were paid for by Land Oberöstereich.

Thursday, October 9, 2014

Last night's lunar eclipse, viewed from space

Each night, an instrument called VIIRS DNB takes visible band images of the entire Earth. When the moon is up, it's really easy to see the patterns of the clouds, and when the moon is set you can basically only see the artificial light from cities. But what happens when you have a lunar eclipse? This:

2014/10/08 lunar eclipse viewed by VIIRS DNB by Christopher Kyba & NOAA
is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at http://ngdc.noaa.gov/eog/viirs/download_ut_mos.html.
Image and Data processing by NOAA's National Geophysical Data Center.

As the Earth's shadow darkened the face of the moon, there was progressively less light for DNB to be able to see land, clouds, and sea. As a result, with each pass of the satellite the image gets darker. The satellite takes about an hour and a half to go around the Earth, so the effect lasts over 2-3 passes. Since we don't have a geostationary satellite capable of imaging the Earth in moonlight, it's not yet possible to produce an video, like this one of a solar eclipse.

For the next several days, you can access the full (giant) resolution image from NOAA. You can get an in-between resolution image from my personal webpage.

If you'd like to see images of hurricanes imaged by VIIRS DNB with moonlight, follow @DanLindsey77 on twitter:

Note for new visitors: This blog is about the Loss of the Night citizen science app, which lets regular people measure how bright the sky is by looking at stars. The goal of the app is to track how the brightness of the sky changes as LED lighting is implemented worldwide. The app is free, and can be downloaded for Android phones. An iPhone version is in development and will come out soon.

Saturday, December 21, 2013

View from your app - architectural lighting in Berlin

If you've ever taken a bus past Alexanderplatz in Berlin at night, you probably wondered what the blindingly bright lights along the side of the train station were for:

Bad lighting at Alexanderplatz 1 by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.
Bad lighting at Alexanderplatz 2 by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The lights are bright enough to hurt your eyes, and as you can see in the two photos above, their glare makes it much more difficult to see the people who are approaching you. From the side, it looks painful and awful, and unless you get off the bus and stand directly perpendicular to the lights you'll never figure out what the lights are for. Here it is:

Bad lighting at Alexanderplatz 3 by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

It's pretty! Unfortunately, almost no one ever appreciates this view, because there is literally no reason to go to the place I was standing other than to take that photo. Take a look at the map below. Nearly everyone experiencing these lights walks between the "Berlin Alexanderplatz" marker to the "S+U Alexanderplatz..." marker, and only sees the bad view shown above. To see the nice view, you've got to cozy up with the construction site:



This is architectural lighting at its very worst! It painfully unpleasant to look at from the most common viewing angle of passers-by, and is directly subverting the goal of nearby public lighting: to improve visibility at night.

As a counter-example, check out this building on Friedrichstraße:

Helios Klinik lights by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Very cool! Different, distinctive, attractive, and with relatively low luminance. Unfortunately, it seems like there wasn't a single lighting plan for the building... A blindingly bright white Marquee at the base of the building entirely spoils the effect that the lighting designer was going for:

Terrible Marquee ruins view by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.


Here's an example of boring, 20th century architectural lighting: Berlin's TV tower

Berliner Fernsehturm with moon by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

One thing I think is interesting about this photo is you can see just how brightly the tower is lit - the full moon appears very modest in comparison. The TV tower is always far more interestingly lit during Berlin's festival of lights, and I have the feeling that it's also far more modestly lit during the festival.

Here's an example of what I call "shine a floodlamp approximately in the direction of the building", the Kirche am Sudstern:

Kirche am Sudstern by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The photo was taken from our research aircraft, and shows what a large fraction of light is wasted when architectural lighting is not done carefully. The ironic thing about badly floodlit churches is that in rural Europe the village church is often the most important source of skyglow for a large region. So the poorly designed lighting actually prevents people from seeing the Godly splendor of the night sky! European churches usually have stained glass windows, and every time I see a badly floodlit church I imagine how much more attractive it would be if the church was completely unlit other than a colorful glow from behind the stained glass.

Of course, it is possible to direct floodlights carefully, as this photo of the Berlin Cathedral shows:

Berliner Dom from air by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

From the air, Berlin Cathedral doesn't look like much, but from the ground it's spectacular:

Berliner Dom from ground by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The difference between the Cathedral and the Kirche am Sudstern above is that instead of just floodlighting the entire building, the lighting designer for the Cathedral chose to highlight certain elements by using a large number of smaller, more focused floodlights. The lighting is still not ideal, however, both because it's quite a bit brighter than necessary and because from the ground level a significant amount of light blinds you when you are looking away from the Cathedral (towards the flood lights:

Glare from the floodlamps of Berliner Dom.

Right next to Berlin Cathedral is another more attractively lit building, the Altes Museum:

Altes Museum at night by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

Unfortunately, I didn't have a tripod, so my photo doesn't do it justice. The great thing about the Altes Museum is that the lamps are totally invisible to the public. There's no glare, and the amount of light emitted to the sky is very reduced compared to many designs.

Finally, we come to the Brandenburg Gate:

The Brandenburg Gate. Photo copyright 2011 C. Kyba.

The Brandenburg Gate does shine quite a bit of light directly up into the sky, but it is a single building in the capital of the country. More than that, the Brandenburg Gate is THE symbol of Berlin, as well as a symbol of all of Germany. As a light pollution researcher and dark sky advocate, I have no problem with the Brandenburg Gate being relatively brightly lit. But not every building is the Brandenburg Gate, and not every church and monument ought to be lit!

Now to be fair, in big cities architectural lighting is way down on the list of sources of light pollution. Nevertheless, I think that people interested in lighting their buildings have a social responsibility to ensure that their installations do not affect public safety by reducing visibility, that they make a serious effort to limit stray light, and that they light the building modestly in order to avoid wasting energy.

If you want to reduce light pollution, the most important thing to get right is street lighting. By coincidence, while I was out taking some of the photos above I snapped these examples of some truly awful "decorative" street lamps (filled with dead bugs) on Unter den Linden:

Bug filled decorative streetlamp by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.
Click to embuggen.

Bug filled decorative streetlamps by Christopher Kyba is licensed
under a Creative Commons Attribution 4.0 International License.

The moon makes an appearance again in the 2nd photo. For comparison, check out these examples of recently installed excellent decorative street lighting from Spain.

Wednesday, September 25, 2013

The view from your app - birds eye view of a searchlight at night

Update: Welcome visitors from EPOD! After you look at this blog post, try out our app! You can read what the app is for here.

I was browsing through some photos from one of our night flights from last year when I came across this image (click to emblinden):

Birds eye view of a searchlight by Christopher Kyba is licensed
under a Creative Commons Attribution 3.0 Unported License.
It's a "birds eye view" of what it looks like when you pass close to the beam of a searchlight. The city appears dark (other than the blinding spot) because I was trying to minimize motion blur. I've enhanced the image below to give you a bit more of a feel for how bright these things look when you view them with your naked eye.


To help give a scale of how insanely bright the spot is, to the bottom left of the big dark park is Potsdamer Platz, and at the bottom right of the photo is Alexanderplatz, two of the brightest areas in the entire city of Berlin. When we fly over a city at night, I occasionally see points of light that are actually painful to look at, even from 10,000 feet up, and in most cases my best guess is that they are floodlights, not searchlights. I can only wonder how migrating birds react to these kinds of lights. Are they blinded? Do they fly towards them?

I am pretty sure that we didn't pass into the exact beam of the searchlight, both because that is statistically very unlikely and because the view looked similar for several seconds (several hundred meters). But you can actually see the beam coming from a long way away, here is a photo from 72 seconds earlier (~3.5 km away), you can still see that the spot is far brighter than anything else in the city:

Distant Searchlight by Christopher Kyba is licensed
under a Creative Commons Attribution 3.0 Unported License.
It's possible that the searchlight was sweeping across the sky, in which case I had a better chance of getting an image just when it was pointed roughly towards me. But of course for a bird flying slowly over the city at night, that will happen over and over and over again!

Note for new visitors: "The view from your app"is a regular feature on this blog, and is intended to highlight good and bad outdoor lighting. The main purpose of the blog is discussing the Loss of the Night citizen science app for android phones.