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Could this be the a new goal of FGFS ?

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Re: Could this be the a new goal of FGFS ?

Postby gsagostinho » Sat Mar 12, 2016 6:26 pm

Thorsten wrote in Sat Mar 12, 2016 1:12 pm:It's all available and documented, I've just not seen anyone use it.


Actually, I started working on it on the regions I created but so far I think I only created a custom one for the Arctic and Antarctic regions:

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Re: Could this be the a new goal of FGFS ?

Postby geed » Sat Mar 12, 2016 6:29 pm

Thorsten wrote in Sat Mar 12, 2016 5:33 pm:I don't know about the rest of you, but I spend 95-99% of my flights in the air looking at things from the cockpit view, and shadows of buildings or other aircraft are so rarely prominently visible from there that I don't consider losing 20 fps a good tradeoff. On the other hand, haze you see all the time during a flight. So ALS implements expensive effects only if you get to see them so often that it matters.


Hmm.. yeah I see where you're coming from. I could actually try what Hamza was doing at EGOD. With aircraft shadows, internal shadows and selected building shadows it could actually be enough.
Sure, the rest of the workload is at the maintainers but that would put the work load into the hands of the right people.

The mapping tech you used in the deferred rendering pipeline is PCF soft shadows?

Let's see. Maybe I get the time to try it out at EGOD and can check the performance impact.
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Re: Could this be the a new goal of FGFS ?

Postby abassign » Sat Mar 12, 2016 10:33 pm

Thorsten wrote in Sat Mar 12, 2016 5:33 pm:ALs has intentionally no shadow mapping because I consider the pain (framerate cost) to gain (shadows mostly) not worth doing it - I prefer burning the GPU performance for other things.


In X-Plane is the possibility to modify the level of detail according to the system performance. In FGFS unfortunately it is missing a single command that would affect the level of detail (The level of detail of X-Plane is not only the LOD ...). It would take a menu item that allows you to choose this important function. Already in older versions of X-Plane there is a function that automatically reduces the level of detail in relation to the minimum frame rate.
I think this solution could solve many problems rightly claimed by Thorsten.

Thorsten wrote in Sat Mar 12, 2016 5:33 pm:I don't know about the rest of you, but I spend 95-99% of my flights in the air looking at things from the cockpit view, and shadows of buildings or other aircraft are so rarely prominently visible from there that I don't consider losing 20 fps a good tradeoff. On the other hand, haze you see all the time during a flight. So ALS implements expensive effects only if you get to see them so often that it matters.


Surely, with the modern CPU, the workload for the dynamic simulation management is very low, 20-30% with my PC (i7-2,5 GHz). Then the rest is all to the user disposal :) I do not think this is bad, rather they are happy to make the 100% CPU and Fgfs if a day will use more than 2 CPU, I will be even happier to see my all 4 cores at 100% load. I bought them and I honestly would not mind to see them work to the best ;) Rightly so if we want to have at least 20 fps is correct to take a limitation (what I have called "level of detail") that can be set either automatically or by user's express wish.

... So I do not see the problem if ALS also manages the shadows like Rembrandt :) ...
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Re: Could this be the a new goal of FGFS ?

Postby abassign » Sat Mar 12, 2016 10:46 pm

gsagostinho wrote in Sat Mar 12, 2016 6:26 pm:Actually, I started working on it on the regions I created but so far I think I only created a custom one for the Arctic and Antarctic regions ...


I always have the impression that one of the reasons why there are few who have faced the editing of effects and the lack of documentation. For example when I wanted to understand how you change a landing strip I went for the file modification evidence "dirt-runway.eff" ... but nothing happened, but if I remove files the track turns gray, or however, that file is used ... Obviously, in this case I suffer from a lack of documentation or rather a lack of know where the documentation that explains how it is organized.
The Wiki would be the right place, but I do not find anything useful, I was unlucky? I have been Incompetent? I hope someone show me the right way ... And at this point, I am sure, I will write an article in wiki that explains it better.
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Re: Could this be the a new goal of FGFS ?

Postby gsagostinho » Sat Mar 12, 2016 11:07 pm

Well, I think the article on procedural texturing is quite complete: http://wiki.flightgear.org/Procedural_Texturing
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Re: Could this be the a new goal of FGFS ?

Postby gsagostinho » Sat Mar 12, 2016 11:40 pm

ludomotico wrote in Thu Mar 10, 2016 2:36 pm:Also, notice the snapshot seems post-processed to add local-contrast (http://www.cambridgeincolour.com/tutori ... cement.htm). I believe this is the only effect FlighGear does not currently provide. In any case, local-contrast is a not realistic effect, it is just an eye-candy effect we are now used to after years of seeing it in "artistic" photographs and many videogames.


I am not sure that image from X-Plane is post processed for contrast. There are plugins in X-Plane which allow the users to control contrast as far as I can remember. And while I do agree that shot has too much contrast and that these sort of effects come rather from a "videogame" aesthetics, I still think that a bit more of contrast in FlightGear wouldn't do any harm. I really find our world a bit too bland regarding illumination.
Last edited by gsagostinho on Sun Mar 13, 2016 11:40 am, edited 1 time in total.
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Re: Could this be the a new goal of FGFS ?

Postby Thorsten » Sun Mar 13, 2016 7:27 am

... So I do not see the problem if ALS also manages the shadows like Rembrandt


It's clear from your description that you don't see the problem - which in reality is not a LOD or detail level issue but a question of the complete design of the rendering pipeline workflow.

And I assure you that shadow mapping in ALS will drive even your machine into low framerates because the graphics card on which to run this hasn't been invented yet, and since if I would do this all complaints about abysmally low performance (yours including) would end at my doorstep and not yours it's sufficient for me to see the problem to stay away from this.


For example when I wanted to understand how you change a landing strip I went for the file modification evidence "dirt-runway.eff" ... but nothing happened, but if I remove files the track turns gray, or however, that file is used ...


Yes, one wonders why you tried to change dirt-runway.eff in spite of the wiki documentation instructing you to do something else, namely

Using a dedicated ALS effect, it is possible to generate a wide variety of visuals for non-paved runways. The effect is used to texture a runway as
Code: Select all
<effect>Effects/dirt-runway</effect>

and the textures and parameters to configure it must be specified in the <parameters> section of the landclass used for the runway.


If you're not doing what the documentation says and it doesn't work your way, there's really no need to be surprised. Just follow the instructions and existing examples, and it will work.

I still think that a big more of contrast in FlightGear wouldn't harm. I really find our world a bit too bland regarding illumination.


Reality is frequently more bland than selected photographs on Wikipedia or airliners.net ... Days with *really* clear skies are rare. In those conditions FG gives you extremely hard shadows and strong contrast - but even a small haze layer softens the lighting pretty efficiently.

We do modify the balance between ambient and diffuse channels according to weather...
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Re: Could this be the a new goal of FGFS ?

Postby ludomotico » Sun Mar 13, 2016 8:19 am

Thorsten wrote in Sat Mar 12, 2016 1:12 pm:I doubt the X-plane things are shadow maps, they look like simple quads. Neither the volumetric shadow technique nor the flat shadow technique in ALS are limited to your own aircraft - they can be added to any object you like (and will in fact work much more reliable on the ground). I think Hamza added them to part of his airport work. Like many things, someone just has to do it.


Checking the X-Plane snapshot in the first post, I'm not sure if the buildings cast any shadow. The jetways and the baggage vehicles do.

Maybe, some artist could define the ALS shadow techniques in some of the most used shared objects: animated jetways, vehicles, lamposts... This will enhance the visuals of all the airports using these shared objects and I guess it is something relatively "cheap" from the point of view of performance.

Anyway, please, check the aircraft shadows in that snapshot. They are double shadows as if there are two suns, and this is definitely not right. It shows shadows is a complex issue and hints that X-Plane is also using some "cheap" trick to fake them, just like ALS does.

(posting again the original shapshot for reference)

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Re: Could this be the a new goal of FGFS ?

Postby pommesschranke » Sun Mar 13, 2016 9:34 am

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Re: Could this be the a new goal of FGFS ?

Postby gsagostinho » Sun Mar 13, 2016 11:46 am

ludomotico wrote in Sun Mar 13, 2016 8:19 am:Checking the X-Plane snapshot in the first post, I'm not sure if the buildings cast any shadow. The jetways and the baggage vehicles do.


In that shot, the sun is almost perfectly perpendicular to the ground, so it's difficult to tell it, but I am pretty sure all objects in X-Plane cast shadows, including airport buildings. E.g.:

Image

I believe that this feature is part of their engine, and so any object in that world will cast shadows.
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Re: Could this be the a new goal of FGFS ?

Postby Thorsten » Sun Mar 13, 2016 11:56 am

I believe that this feature is part of their engine, and so any object in that world will cast shadows.


This seems frankly unlikely, as there's no rendering technique which can deliver this. Shadow mapping is good, but can't handle transparency - so trees or clouds can never cast shadows using mapping. It has also accuracy issues, you need to map large regions into a texture buffer.

Other shadow techniques however are targeted to a specific use case.
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Re: Could this be the a new goal of FGFS ?

Postby psadro_gm » Sun Mar 13, 2016 12:21 pm

Looks like x-plane is also experimenting with deferred rendering. This page contains all the disclaimers :)

http://developer.x-plane.com/2010/08/x- ... umination/
8.50 airport parser, textured roads and streams...
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Re: Could this be the a new goal of FGFS ?

Postby geed » Sun Mar 13, 2016 4:04 pm

X-Plane has something they call Global Shadows and it seems that it is shadow mapping over all objects in the visual range, probably a couple of textures with some LOD behavior and degeneration over distance.

So it might work in terms of performance but it is heavily dependent on the object tree structure. Collecting all objects for the shadow rendering over a distance.

The selective aproach, Thorsten favores, might give better results as it is result oriented on a small scale. If scenery maintainers activate shadow rendering for selected objects, it might be a good trade between performance and visual quality.
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Re: Could this be the a new goal of FGFS ?

Postby abassign » Mon Mar 14, 2016 4:14 am

gsagostinho wrote in Sat Mar 12, 2016 11:07 pm:Well, I think the article on procedural texturing is quite complete: http://wiki.flightgear.org/Procedural_Texturing


I know this story, but unfortunately does not define a clear structure of the files that combine to create the effects. I think it would be useful to include a preamble that clarifies the locations of the files and what parts of them are to be changed to change the effects. Not only that, but it lacks an essential fact, when the change of the effect is displayed? You must restart each time the program? Same goes for other similar articles concerning ALS effects on the aircraft.
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Re: Could this be the a new goal of FGFS ?

Postby abassign » Mon Mar 14, 2016 4:40 am

psadro_gm wrote in Sun Mar 13, 2016 12:21 pm:Looks like x-plane is also experimenting with deferred rendering. This page contains all the disclaimers :)

http://developer.x-plane.com/2010/08/x- ... umination/


Looking at the X-Plane notes can be read:
Global illumination isn’t going to be free. The main cost is an increase in VRAM use and fill-rate. The cost of global illumination is mostly a one-time cost to put X-Plane into a new rendering mode. (Graphics nerds: global illumination is implemented via deferred rendering.) The incremental cost of lights isn’t that high, although a scene with a lot of lights will have impact.

In fact I understand that X-Plane uses a method similar to Rembrandt (which in fact can give very realistic results) trying to optimize it with performance. Indeed, the quality of the "light" Rembrandt is significantly better than ALS in the images to "short range", while in "long-range" ALS is considerably higher. In fact, in this discussion, no one doubts the best quality of FGFS on a great distance placed elements.
I always had the impression that Rembrandt was abandoned too early, when it was still able to show its true potential. Sure it's expensive at this level of CPU and can lower the frame rate (not sure though if with better management of multiple CPUs can improve it by changing, in a proper mode, the code).

At the same time I do not want even to read comments on slowing the frame rate, X-Plane allows you to enable or disable the function of the shadows at any time (as indeed it could be done at the beginning with Rembrandt) in order to allow more realism in flight phases carried out on land, where the frame rate is less important, then, to regain a good frame-rate in flight. However I think be able to combine the two methods, Rembrabdt for near objects, and ALS for distant objects, it would probably be the best solution.

Not only that, but the note of X-Plane, says the approach is "expensive" (quality costs is not free ...), but in anticipation of the improvement in the quality of CPU-GPU, will become more and more usable. What I've always said in various posts, including this .. every user should have the freedom to exploit his system as he wishes with the frame-rate they want. If a user has a CPU-GPU obsolete clearly it tend to not activate the Rembrabdt method, but if it has a sufficient configuration will be happy to activate this feature. I've already said when I pointed out that it would be useful to make a ALS-Rembrandt merge. Obviously then if there are better alternatives ... better yet ... Thorsten spoke that can activate the shadows in ALS, as it knows how to do, it would be very nice he did it and allow us to verify the performance and quality level.
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