m2fkxy

Mad dogs are MD-80s.

That's true. I have a bias of having part of my formal education quite focused on geospatial topics. Seeing non-geospatial folks reinventing wheels taught in GIS 101 both makes me smile and grimace thinking that we have have been doing something wrong with basic tools and aspects of the trade not being wider known.

You can look into TopoJSON here: https://github.com/topojson/topojson And a good general introduction to topology in GIS setting is nicely found in QGIS documentation: https://docs.qgis.org/3.40/en/docs/gentle_gis_introduction/t...

> A side effect of the geometry simplication is that there are some very small gaps between states. Based on your use case, you'll need to handle the case of the point not being within any state borders. In these rare cases, you could fall back to a different method, such as distance checking centroid points, adding an episilon to all state borders, or simply asking the user. (The user may also be in another country or in the ocean...)

This is a common topic and easily dealt with by working with topology-informed geometries; most simplification algorithms support topology handling between different features. For instance, TopoJSON can be used.

it depends on what flavour of English you speak. British English for instance tends to use plural for collective nouns.

This sounds like marshrutki. These are very common in post-Soviet countries to fill the demand left unmet by public transportation service.

the TCAS data would have been displayed. but not on instruments or in any place that you typically pay attention to the most during final visual approach (ie., mostly outside).

TCAS RAs are inhibited at low altitude.

yeah, and then you need to get refreshed orbital elements for those satellites. not good if you are in an airtight environment.

celestial ephemerides don't change nearly as much.

your point being?

...which is obviously designed to be maximally visible from the public space.

it's useless thence I love it.

I lied, in fact I just used it to create a couple Slack emojis.

> Plausibly, there is no real monitoring of co-orbiting bodies in space

[capable] nations operating sensitive satellites and other space assets absolutely are monitoring foreign objects maneuvering in their orbital vicinity.

not at all, I love it too

it's also not the proper scale type for sequential data (red/green is diverging, but there is no central value defined in the linked map).

  For those less obsessed with SAR images

Touché!

Also good point regarding multibounces and multipath. I would expect eg. landing gear returns to be standing out in those cases (cockpit too, although probably the canopy is coated to prevent radar penetrating).

Yes, radar shadow is how you would find it. But your sensor must be performing well enough for it to be able to distinguish a shadow from the surface backscatter (ie. radar signature) the aircraft is sitting on. This is usually not a problem for rough surfaces (eg. grass or dirt, or some types of pavement), but it can be more problematic for surfaces with more specular scattering.

A little nitpick about:

  The number of looks correlates with a higher resolution.

Yes and no. When you task an image, you usually (as is the case with Umbra) specify your desired ground resolution, eg. 25, 50, 100 cm, etc. There are two dimensions in a SAR image: range and azimuth. Range resolution is determined by the SAR system bandwidth. Azimuth resolution is determined by the integration angle (the angle formed between your target and your satellite from start to end of the collection).

Let's assume you want a 50 cm image. Your range resolution will be equal to that and, in a 1-look image, your native azimuth resolution will also be 50 cm. What happens when you request a multi-looked image, is that the satellite will collect data over your target for a longer amount of time (and thus over a greater angle diversity). Range resolution will not change; however, in the natural ("native") image, you get asymmetrical pixels: taking the same target resolution of 50 cm, a 2-looks image will have a 25 cm azimuth resolution. For 3-looks, ~16 cm. And so on.

What then happens during the processing of derived products (eg. GEC) is that the pixels are squared: to do that, you have to average out the pixels in the azimuth dimension. This greatly improves what is called the radiometric resolution (ie. how much information a pixel contains), by cancelling out the speckle and averaging the noise. But for all intents and purposes, on a multi-looked image (which is what the GEC products that you use are), spatial resolution remains the same, square pixel.

[SAR nerds here: I am not mentioning the slant-range-to-ground-range process, and I am also ignoring the resolution vs. sampling distinction for simplicity]

yes, received power is inversely proportional to the distance squared. it's hard to overstate how ridiculously small the amounts of power are at play with spaceborne SAR systems.

most complex and/or commercial aircraft do share the workload between a pilot-flying, and a pilot-non-flying—in addition to the captain & FO hierarchy you are probably aware of.

the conning officer often has tons of other stuff to deal with that require them not to be distracted by having to change course themselves.

wait, that was not a joke?

bad week for upper stage engines!

not sure why you are getting downvoted, that was a funny reference to Ariane 501/V88.

not a single mention of hearing protection?

also, by the physics of synthetic aperture radar, UMBRA (or any other satellite operator for that matter) can only collect 16 centimetres data at an angle equal or greater than ~45 degrees off-nadir (and for UMBRA, less than ~60 degrees off-nadir). this further restricts the footprint of feasible data collection.

I am just a half-educated layman when it comes to SAR, which has a very heavy electrical engineering heritage. I hear that one very good technical resource is this book written by Iain Woodhouse [1], but I would be lucky to understand a tenth of it myself.

There is also a very good SAR vulgarisation book written by Tom Ager [2].

[1] https://www.routledge.com/Introduction-to-Microwave-Remote-S...

[2] https://www.amazon.com/Essentials-SAR-Conceptual-Remarkable-...

Nadir-SAR would look very confusing, full of ambiguities, and probably unexploitable since the ranging part of RADAR would not be able to distinguish the left returns from the right returns -- that's why SAR is side-looking.

even with a strictly side-looking geometry, images collected closer to nadir (steep/low incidence) start exhibiting some artifacts such as nadir returns [1].

[1] https://www.researchgate.net/figure/Example-of-nadir-echo-in...

Calm water surface is a specular scatterer, meaning radar energy will be reflected away, and proportionally so as the incidence angle increases.

Images collected at lower incidence (closer to nadir) might feature very bright surface water if it is calm, as more energy is reflected towards the radar.

Rough water surface is a diffuse scatterer, and will generally appear brighter than calm waters.

It actually does not absorb radar energy, rather it reflects it away (specular reflection). That's why rougher sea surface appears brighter on SAR as it turns from a specular to a diffuse scatterer. Furthermore, in some specific conditions (low incidence angle, closer to nadir), calm water can appear much brighter than other land surfaces.