"Viewsheds" of any location can be calculated and matched with photographs using "GeoImageViewer", an application I wrote a couple of years ago. Any feature in the image can be interactively identified in a mapview and vice versa, including the boundary of the viewshed. As has been mentioned in the comments, it is essential to include atmospheric refraction in the calculation, at least for distances above ~100km.
I'm the author of the post. Do you have any knowledge about how refraction can vary? I was wondering about calculating the world twice, once with a lower refraction bound and then again with an upper.
Atmospheric refraction is due to the vertical gradients of atmospheric pressure, temperature, and composition of the atmosphere, all of which are usually not precisely known, and which vary with time, so one gets larger lines of sights at certain times. For my application I used the standard formulas for astronomical refraction (-> many weblinks) with constant medium gradients. If I recall correctly this results in ~100m height correction for features in 100km distance and ~400m in 200km distance (features appear higher than without atmospheric refraction). For your application it would make sense to use two extreme values for the gradients to get maximum and minimum, as you suggested.
Right, yes variance over time is what I was referring to. I did a bit of research and indeed there seems to be some evidence backed minimum and maximum values I can plug in. But it's quite a variance! Now I'm thinking I should do min, max and average.
This looks amazing! I recently moved to an apartment with a good view out the window, so I was excited to try this to identify some of the more distant hills I can see. Alas, it seems to have developed some bugs in the 4 years since the last commit… when I tried clicking in ‘Edit Mode’ to select a location, nothing happened and I couldn’t continue. Any chance you could look into updating this application?
I’ve been using such tools already (in particular https://www.udeuschle.de/panoramas/makepanoramas_en.htm). But for smaller or more distant features, I’ve found it can be difficult to correlate their physical appearance with their appearance on the diagram. A calibration tool like hdersch’s would make this much easier!
What is definitely wrong in this article is the claim, that only bears eat living prey. Also wolves do that. There are many cases where wolves attacked animals (cows, sheep, deer), and as soon as those are immobilized, start feeding. Sometimes these animals survive with horrible wounds. Many images and videos can be found via google.
Nature is brutal, we should all be really thankful that we get to die in a bed being made as comfortable as possible. For every other animal in history death was almost guaranteed to be something scary and painful.
I doubt that statement was meant to be some kind of absolute rule, big cats will definitely eat you alive if they feel like it. But at least you are perhaps more likely to get a quick death..
The advice I grew up with (in swedish bear country) is to do these things, in order:
1. Make noise while in the woods, bears will generally avoid you if they know you are there. You don’t want to startle a bear.
2. If charged, stay calm, make yourself big and talk to the bear, move slowly.
3. If attacked, play dead.
With luck, the bear will lose interest once it doesn’t perceive you as a threat. If it’s hungry, well, bad luck. There have been cases of people scaring bears off by punching them in the nose, so as a final resort I guess that’s something to try.
In the hierarchy of fucking with things and getting fucked with ,think of yourself as one of the first.
If your solution to problems is sentences that start with so, you are food. What can help is a warmup to kill display. Means,you show a little magic show of dexterity while moving forward. Throw a knife up and down,raise internal doubts.Suprises kill the predator mood.The predator being used to your presence is thus bad.
I think it is extremely common in the animal world, if not the default. Thinking of other biomes Fish and reptiles almost always do it. I suspect anything which a substantial size difference does it and it is only avoided when you have pretty that is very dangerous to the predator.
Yep. That keeps happening e.g. in the mountains in northern italy. Cows with huge wounds stumble back from the field, it's horrific. And when the farmers kill a wolf it's an outpour of indignation from animal welfare :/
Mastiff dogs are the real culprits in more cases that people would expect. Had been videotaped doing exactly this. A wolf pack will kill the prey, two mastiffs just bite, sit and wait watching the cow die. They can't kill the cow efficiently.
They will respect animals in their "family" herd, but don't have this restriction against cattle from other herds or species that are not defending, specially when not feed accurately by the owners (If they guard sheep they can still see young cows as fair game).
The main difference between wolves and shepherd dogs is that dogs aren't neither afraid to cows or men.
Combined cycle power plants take heat at 2000°C using a combination of gas and steam turbines. Their conversion efficiency to electric power is 52%, see Wikipedia. This is proven technology, at least 30 years old, and quite a few of those exist out there.
Steam turbines alone can be operated at higher temperatures by using mercury instead of water. Some plants using this approach were built in the 1920/30s.
I mentioned GeoImageViewer in a reply above. It contains several algorithms to determine the location of a landscape photo given some control points selected on a map. It is also able to determine lens parameters (fov, distortions,...).
https://hdersch.github.io/
GeoImageViewer, not an overlay but side-by-side view of photograph and maps. Clicking the image anywhere (not just precalculated pois) shows corresponding location in map and vice-versa.
https://hdersch.github.io/
Nernst sold the patent in 1902 for 1 Million Mark to AEG, which corresponds to roughly 10 Million EUR today. It was one of the highest valued patents at the time, and is still quite impressive today.
A comparison with one of the many SIMD-mathlibraries would have been fairer than with plain libm. Long time ago I wrote such a dual-platform library for the PS3 (cell-processor) and x86 architecture (outdated, but still available here [1]). Depending on how standard libm implements atan2f, a speedup of 3x to 15x is achieved, without sacrifying accuracy.
There are many projects displaying georeferenced photographs using Leaflet, which usually work via precalculated hotspots in image- and mapview. Here's a project that uses photogrammetry to link not just some but all points. Clicking the photograph zooms into the corresponding position in the Leaflet-view and vice-versa.
[1] https://hdersch.github.io/Viewing.html