Often I see a picture of earth taken from space and North is not at the top. Recently some pictures of the Rim Fire were on Slate. Some have north at the top but one has East at the top. Bad Astronomy - Aug 27
Do we know why North is not always at the top? Do websites have some problem rotating pictures? Do they not care?
There is no “top” in space, so why would they care?
Geeze! There is no “top” on earth either. It is a map-making convention. We care? Why does Slate not care? Why does Slate not rotate the picture?
Not only do we not care about rotating pictures of earth in space, we also don’t care about rotating deed maps and public works project plan maps to put north at the top of the page. We orient the image to show it to best or easiest advantage and then we put a north arrow on it, pointing the right way. That’s usually an arrow with a capital N that looks like it’s pole dancing on, or has been skewered by, the shaft.
As a for instance, in this plan the length of the street is oriented to match the long dimension of the paper and the north arrow (looks like a less-than sign in a circle in the lower right) is pointing almost straight left.
Better link for Bad Astronomy. (The article will be bumped off of the front page in a day or two.)
And all I’m seeing there are N^. Maybe Slate had an E^, but it’s not at that link now.
If they were really oriented, east would be at the top.
If it’s a satellite image, prior to release it will have almost certainly been rectifiedto it’s correct orientation and (depending on the format) will have it’s coordinates encoded somewhere in the file header information. A lot of the information used for rectification will be known: date/time, orbital position, camera/sensor azimuth, altitude etc. This is all for use with mapping/GIS software.
A snapshot taken with a regular camera, by an astronaut on the ISS for instance, won’t have any of that information with it (at least not precise information) and it’s not really important for a story like the *Slate *one. Often there will be a text note indicating North or another direction and that’s all you need for a story.
Some of it will also be for simple formatting reasons. The BA article has a mosaic of four images which make a nice rectangle shape and fit with the page. Taking a snapshot or other image and rotating it can shift the image in all sorts of odd ways and it looks pretty bad for a web-article. You see that kind of thing a lot in scientific publications (especially geological ones - which I used to work on) but for the most part it’s just adding another unneeded step to the process.
But we’re not talking about maps, we are talking about photographs. Do you rotate the photos in your family album so that north always points up?
Generally photographs are oriented so that the sky is up, even where the sky is not visible. If the camera were pointed straight down it wouldn’t matter much, but otherwise photographs have a correct up and down, and should not be rotated.
The BA article with the time-sequence mosaic is from NASA’s Suomi NPP earth observation satellite. The “natural” orientation of images from that spacecraft is a rectangular swath approximately 3,000 km wide (approximately east-to-west) x 550 km long (approximately north-to-south). This swath represents the full width of the field of view of the VIIRS instrument and 30 seconds along the spacecraft’s orbit. I say “approximately” with respect to compass orientation because the true orientation of the images is along the spacecraft’s ground track, based on its near-polar orbit… its circular orbit is oriented approximately 9 degrees off true north-south, so the centerline of the baseline image is tilted 9 degrees from true north-south.
For more information than you may ever need on how to understand Suomi NPP VIIRS imagery, here’s a nifty doc from the Colorado State University’s CIRA team.
Anyways, none of the images from the Suomi NPP (or from Terra MODIS, the source of one of the other images in the BA article) are in their “true” or “native” orientation, because ground processing provides precise geolocation for each and every pixel in the image (at least in the case of VIIRS… I guess probably true also about MODIS), so it’s easy to splice and reorient images in post-processing to meet the typical “north is up” expectation, and to precisely align images from subsequent orbital passes.
But the “mis-oriented” image is from a hand-held camera stuck in a downward-facing porthole of the ISS, so there’s no real possibility of automatic post-processing of the image to rectify its geolocation.
The problem is not with the creation of the image. The problem is with the publication of the image.
WAG - Editors today take what is given to them and they do nothing more. Unless an effort is made during the publication process to orient images according to the map convention (e.g., north at the top) we get what we get. In days of yore people actually cared about doing the job well. Apparently Slate editors today do not.
It’s a map-making convention, but you’re not talking about maps, you’re talking about photos. Photos represent themselves as presenting the angle of view of the person who took the photo. So the convention that applies here wouldn’t be to put north at the top, but to present the view entailed by the orientation of the human that took the photo.
I would say the editor is doing their job and should not alter the photo in any way.
No one is asking to alter the image. Looking at the OP’s link they have an image showing wildland fire smoke from a California fire. For some strange reason they took the portrait mode image and published it landscape mode. It appears just so it fits within the layout of the web page. It’s a poor design choice.
Assume for a moment that the convention is that pictures from space should always have North at the top.
Now:
If the picture is taken directly down on Earth over the North Pole, how would you orient the picture?
Let me guess: Put East on the top? I mean, when you are at the North Pole, every direction is south…