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Photoscenery?

Questions and discussion about enhancing and populating the FlightGear world.

Re: Photoscenery?

Postby Hooray » Fri Mar 26, 2021 6:20 pm

Keep in mind that, depending on your perspective, FlightGear has a very liberal license (GPL) and that the nature of the GPL also means that recipient of GPL'ed contents must also follow the GPL - which is basically a no-go for any commercial/proprietary entity. And furthermore, while public domain imagery/contents would obviously be fine, continually fetching GBs of identical images over and over again by FlightGear clients would almost certainly be an annoyance, if not even a service violation. Which is to say, even just a handful of FlightGear clients connected over MP, participating in a virtual MP event, could bring down most public services to their knees.

In other words, other service users (free or paid) would almost certainly be affected by a handful of fgfs clients fetching imagery for hours.

Thus, it's generally not a safe assumption that people/companies will gladly provide such services, even if the underlying data/tiles/imagery is available free of cost, that does not mean that serving/distributing such data can be offered for free.

So you have the license of the data itself, but also the service cost associated with making the data available.
Note that this also is the issue that affects FlightGear scenery as a whole (terrasync hosting), but also fgdata hosting (git specifically).

So people really need to work out a solution that addresses both issues, even if these are currently not yet perceived to be real issues, they are likely to become very relevant over time, especially the very instant you start providing a solution that's of interest to the MP/terrasync community.

That is one of the reasons why I mentioned the scenario, where standard reverse proxies would be set up by volunteers in the FlightGear community, there also also proxy server implementations specifically for WMTS/WMS - the corresponding URLs could be pre-configured in fgdata space, so that we'd host our own network of GIS "mirrors" without actually violating any TOS, while ensuring that the actual services would only ever get to see requests that have not been previously made.

Besides, this is also a scheme that's basically in use with other tools/services, including other flight simulators. And such a scheme could also be sufficiently generic in nature, so that it might actually be of interest to the parties providing the actual geoservice - so that such FlightGear proxies/geoserver mirrors could also be used by other projects.

Simply expecting that they're going to tolerate possibly hundreds of GBs of requests per week, is unlikely to be viable in the mid-term.
The other issue being one of adding an implicit dependency, i.e. requiring 3rd party services for a more or less vital component of the sim.

Thus, even if you could get a written statement to approve such use, that would not necessarily solve all potential problems magically.
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Re: Photoscenery?

Postby vnts » Sat Mar 27, 2021 1:11 pm

oracle wrote in Thu Mar 25, 2021 6:14 pm:I'm trying to understand this discussion but I'm missing a lot. This is a multi-year project, so I'm not sure what is still relevant and what's outdated.

How is the current scenery (v 2.01) built? What is the source of the terrain images?For example, I'm looking at a big city which in FG looks nothing like what it appears on Google Earth but the mountains around are relatively similar to reality.

Then there are roads and railways etc. which appear almost exactly where they are, just in unrealistic colours (like they are drawn from a model on top of the terrain).

Is none of this photographic data?

On the topic of free satellite scenery: I understand there are sources of free images but the images are not free to redistribute. So they cannot be used to create tiles like the ones currently available (e000n10, e000n20, etc)?

There aren't 'images' as such for terrain. Photos don't do what people would intuitively expect or hope for - see to the end of this earlier discussion for surrounding issues with different approaches: link .

The World Scenery 2.x (WS2) system has a mesh broken up into blobs of landclasses. Shaders then 'paint' the mesh with what would be seen at that time and season, weather, etc. As Thorsten said FG has a lot of advanced tech even without WS3, and is at 10% of it's potential awaiting data/art contributions. See procedural texturing: link. WS3 (link) fixes the limitations/quirks with WS2.

The current 'photoscenery' layers a photo as the base texture, and does the procedural texturing over it, including seasons/snow/rain/etc. It's more like a combination of FG's ALS techniques with photoscenery - i.e. not what you see in other sims . Some steep surfaces like rock are left untouched since putting a photo over them doesn't work well (photoscenery could do this for other landtypes based on the steepness/normal). Water is a tradeoff, it has nice gradual transition using phtoscenery which is a limitation of WS2, but is like a painted road with one colour in all conditions, and doesn't have wave cues AIUI(?) (i.e. bad for landings).

As for the appearance of cities, they will be replaced with 3d objects from an OSM2City world build in FG 2020.3.8+ . This is available on sourceforge right now as a soft release, and will be likely announced within a few days. See this page: link. That includes roads and railways which will be 3d objects on top of terrain - their appearance is place holder and can be improved/regionalised. Since you are using next branch for photoscenery (or not installed it yet?) you should be able to see OSM2City output.

See https://wiki.flightgear.org/Howto:Impro ... f_interest for where the appearance of things you see in sim comes from and is configured/improved.

As for mountains and other areas outside cities looking realistic, there's a lot of simulated weather and environment to configure - to tweak/enable see link to check if you are seeing everything as it should look like.

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Re: Photoscenery?

Postby abassign » Mon Mar 29, 2021 12:19 am

Hooray wrote in Fri Mar 26, 2021 5:05 pm:Another idea was using the Canvas system to fetch images automatically by setting URLs via Nasal scripting.


If canvas continues to use the same thread of system and NASAL .. I see this solution really difficult with only one task... At this point it is better to use a completely independent program that performs the download according to the position of the plane by TCP or ODP protocol using the point of view and the images not loaded in area. In Python it works fine and doesn't load the FGFS thread.
Developer of the program https://wiki.flightgear.org/Julia_photoscenery_generator
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Re: Photoscenery?

Postby Hooray » Tue Mar 30, 2021 10:09 am

Please look at any of the canvas image examples to see for yourself that raster images loaded viathe canvas are indeed loaded asynchronously using the OSG ReaderWriter machinery and HTTPClient for URLs.

This is why you don't see FG blocking while it is fetching images over HTTP. And that was indeed the motivation for considering the canvas here.

However there are other issues due to how the tile cache/tile manager work.

Basically you need an IPC mechanism to link both systems and communicate updates properly.

As usual, it's a good idea to look at the docs/examples before speaking up :wink:
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Re: Photoscenery?

Postby oracle » Tue Mar 30, 2021 10:28 am

The rationale behind my interest in photoscenery is this:
1) The scope of the sim is the world and the world is big. So modeling the whole terrain is a hell of a task.
2) The variety of colours and shades on the globe is huge.
No reasonable amount of painting and texturing can be expected to come close to representing accurately such richness on such a massive scale.

So I thought if we could have actual images instead of textures as background, that would save a lot of work and the scenery would look like what it really is.
I see now there's a lot more complexity to it:
1) Problems with image ownership and usage permissions;
2) Problems with hosting and handling the download traffic;
3) Problems with memory and processing power usage;
4) Problems with (dis)continuity.
I haven't actually seen a source who offers seamless imagery. The photos have "stitch" boundaries and what we usually see on the boundary is a little misalignment, difference in the angle the shots were taken from, difference in colours, even objects which appear cut because of the different time of capturing (like a road with traffic on one side which wasn't built when the neighbouring shot was taken and seems to end into a field), etc... So there goes my hope of smooth view.
5) Effects of light and seasons. Things don't look the same at sunrise, noon, sunset (not to mention night) and clearly we'd like different appearance between summer and winter. It will be weird to have green nature all year round (most images tend to be from the summer).
6) Images are flat but from a little closer things are 3D. Even with very hi-res photos we'd still be missing the height dimension of everything. That is, in order to get better realism, we'd still need buildings and other objects overlaid on top of the photos. And there will be a conflict of shadows as well (which hopefully won't be too annoying).

With all that said, if I take a free sat image, pre-process it as required, put it on my server and make it available to FG users, would I be violating anyone's rights?
Is it possible to have the scenery displayed in layers and apply effects on them? Like lay surface photos over a global elevation model to achieve the overall shape of the terrain, then paint 3D objects and roads, rails, etc and airport models? And finally, apply light and weather effects? Seems possible based on the post above by vnts.
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Re: Photoscenery?

Postby ludomotico » Tue Mar 30, 2021 10:49 am

oracle wrote in Tue Mar 30, 2021 10:28 am:With all that said, if I take a free sat image, pre-process it as required, put it on my server and make it available to FG users, would I be violating anyone's rights?


Probably. You must ask this question to that "free" sat image creator.

Is it possible to have the scenery displayed in layers and apply effects on them? Like lay surface photos over a global elevation model to achieve the overall shape of the terrain, then paint 3D objects and roads, rails, etc and airport models? And finally, apply light and weather effects? Seems possible based on the post above by vnts.


Yes, to all of this, by default, no need of any action from your part. But these answers are obvious if you have run FligtGear just once, so I guess you mean something different: viewtopic.php?f=5&t=37866&start=180#p377969
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Re: Photoscenery?

Postby vnts » Tue Mar 30, 2021 1:55 pm

oracle wrote in Tue Mar 30, 2021 10:28 am:The rationale behind my interest in photoscenery is this:
1) The scope of the sim is the world and the world is big. So modeling the whole terrain is a hell of a task.
2) The variety of colours and shades on the globe is huge.
No reasonable amount of painting and texturing can be expected to come close to representing accurately such richness on such a massive scale.

With procedural texturing the entire globe doesn't need to be painted, as such. It is possible to define variation over the entire Earth though math, and define that variation at different scales - from kilometers to blades of grass. This math can be used to create textures and effects that don't repeat - but can be recognised as the same type of surface to the eye. Sort of like how you can recognise surfaces with gravel, beach, grass, patchy grass, mud, etc. without the exact bits of gravel, sand, or grass blades having the same position/size. The way it's setup is the terrain is split up into landclasses, and each type of landclass in each region can have its own look that doesn't repeat https://wiki.flightgear.org/Category:Sc ... h_settings .

One of the ways existing WS2 textures are developed is to take clear bits of aerial photos and process it in GIMP so it's suitable to be used as an input texture to procedural texturing - and so the colours don't conflict. Erik did a further texture match for 2020.3 LTS.

If you have a look at the scenery using UFO, with ALS on, and with shaders maxed at one of the airports in developed areas here https://wiki.flightgear.org/Suggested_airports like ENBR, you can see what I mean.
oracle wrote in Tue Mar 30, 2021 10:28 am:2) Problems with hosting and handling the download traffic;
3) Problems with memory and processing power usage;

High resolution photoscenery can improve smaller regions that haven't been developed/updated in FG. But it won't improve the experience for other people unless a source with a good license is found - a source that doesn't have terrible consistency or quality. As you say it's hard to make it practically available as default scenery due to size. If an area is made available as custom scenery, it will only improve that area for a handful of power users that know of it.

It's also the case that with a similar effort clear and crisp parts of the high quality photo-scenery could be made into regular WS2 scenery - with the result that the overall look is crisper after tweaking, and object placement maps line up with textures (like trees and edges of fields). Improving WS2 will also improve WS3 - as the regional definition system is compatible with both. The procedural system is designed to allow people have a huge impact by text-file changes, and by creating input textures from photos to cover large regions.

USGS images are likely under a GPL compatible license, and a publicly share-able example custom photo-scenery would be useful for testing (including making sure the feature doesn't break in future builds on some systems) even if the quality is not that good .

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Re: Photoscenery?

Postby oracle » Tue Mar 30, 2021 5:48 pm

I appreciate all the work done with the procedural texturing. Now that I know more about it, I appreciate it even more.

At the same time, it has its limitations. Consider 3 examples:
1. London. I took a screenshot, just don't know where to upload it.
What I see is a few very rough, out of proportion 3d buildings and stripes of repetitive city image tiles. Central London appears like some remote neighbourhood.
2. JFK Canarsie approach. Scenery is so inaccurate that the Belt highway appears to be floating in the water. Like roads are misaligned with the shore.
3. How about natural wonders such as the Grand Canyon? The real thing is incredible, with complex shapes, terraces of rocks of different colours and the river at the bottom and what have you. How could you possibly model that without good images of the actual place?

Clearly sat pictures won't be enough in these cases either but they would bring a good starting point.
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Re: Photoscenery?

Postby D-ECHO » Tue Mar 30, 2021 6:04 pm

Hi oracle,

1. to upload an image, you have to upload it to an image hosting site (I typically use imgur.com, but there are others such as iirc flickr etc.). Afterwards, you get the direct link to the image (.png or .jpg, but note that jpg images are usually preferred, because they load a lot faster and take up less network bandwith, especially if you want to contribute to image threads in the Media subforum later on). You put this link between
Code: Select all
[img]image url[/img]
tags.

2. This is mostly due to the quality of landcover data available when the current world scenery (WS 2.0) was built. Especially with OpenStreetMap coastlines available, a new scenery build would improve this situation a lot.

3. The Grand Canyon in FG looks pretty spectacular, especially due to procedural texturing that allows to use effects in order to render the rocks probably: See Image for example. When you compare this to photoscenery, e.g. viewtopic.php?f=3&t=37810&p=373661&#p373661 (MSFS 2020) you clearly see the limitations that in turn photoscenery provides, especially that it has a lot of problems with shadows and whenever the surface you render it on is too steep (a simple projection problem, think of it like using a movie projector, but projecting it on the sidewalls instead of the front wall).
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Re: Photoscenery?

Postby erik » Tue Mar 30, 2021 6:59 pm

For FligthGears Grand Canyon see also: viewtopic.php?f=19&t=36401
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Re: Photoscenery?

Postby oracle » Tue Mar 30, 2021 10:21 pm

Thanks for all the info.
Here are my screenshots. I've flown over London multiple times (as a passenger) and it has never looked anything like this. Central London is so densely built up that you'd hardly see any green spaces between the buildings - except for the few parks / gardens.
Then look at New York. The highway that appears to float in the water is actually on land. It has a few bridges but nothing like this here.

Image
London - a few buildings and stripes of repeating tiles

Image
New York - Belt Parkway in the water and stripes of repeating tiles
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Re: Photoscenery?

Postby erik » Wed Mar 31, 2021 7:59 am

As vs already explained, world scenery 2.0 is rather old and except for a few places (noticeably Europe) the (freely) available terrain classification data back then was rather course. Causing those problems like highways running over water. World Scenery 3.0 (ws3) should take car of that.

Luckily OSM2City would hide a lot of the city problems.

Image

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Re: Photoscenery?

Postby erik » Wed Mar 31, 2021 8:15 am

London in next with OSM2City:
Image

Urban UK (west coast):
Image

Image

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Re: Photoscenery?

Postby montagdude » Thu Apr 01, 2021 4:41 pm

erik wrote in Wed Mar 31, 2021 7:59 am:As vs already explained, world scenery 2.0 is rather old and except for a few places (noticeably Europe) the (freely) available terrain classification data back then was rather course. Causing those problems like highways running over water. World Scenery 3.0 (ws3) should take car of that.

Luckily OSM2City would hide a lot of the city problems.

Image

Erik

To be fair, that is not the default WS 2.0 terrain. I happen to know because I created it. :D
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Re: Photoscenery?

Postby oracle » Thu Apr 01, 2021 5:20 pm

I spent some time looking for free, consistent imagery of the world. USGS didn't offer anything interesting for the area I selected.
What I found is that the ESA Copernicus program has a great license and claims to cover EU countries in good detail.
The images I got so far have resolution 10m - sadly worthless for flight simulator scenery. I don't know yet if they offer something other than Sentinel-2 data under this license but there's a lot to explore.

The license says:
EU law grants free access to Copernicus Sentinel Data and Service Information for the purpose of the following use in so far as it is lawful:
(a)reproduction;
(b)distribution;
(c)communication to the public;
(d)adaptation, modification and combination with other data and information;
(e)any combination of points (a) to (d)

https://lta.cr.usgs.gov/sites/default/f ... itions.pdf

What do you think about this?
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