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FIAT G91-R (Gina) - JSBSim

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Re: FIAT G91-R (Gina) - JSBSim

Postby J Maverick 16 » Mon May 30, 2016 2:10 pm

THAT "texture" is really sexy! 8)
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Re: FIAT G91-R (Gina) - JSBSim

Postby abassign » Mon May 30, 2016 9:46 pm

J Maverick 16 wrote in Mon May 30, 2016 2:10 pm:THAT "texture" is really sexy! 8)
Regards, Maverick


True, I would say very simple, since I'm just applying the effect of reflection, to see the defects on the surfaces immediately. We are very picky ...

Much better the effect of the lights that I find interesting, I applied the methods that I find Thorsen excellent and I want to focus on this aircraft to work with ALS that I find very interesting, then if someone wants to put great Rembrandt ... so much the XML-code NASAL (being programs) is under the GPL.

Image

The lights are my pride, a 3D model so nice finally deserves as I see the lights of FSX or X-Plane, or that look like the reality and not to be stellar effects like Hollywood! I would like that other programmers do the same for excellent airplanes like the C172P, the DHC6 and many others, the sense of reality comes from small things, from details, so I hope that this ability to see "the beautiful" ( present in the DNA of us Italians ... ;) ) is implemented by others and will become the new standard of FGFS aircraft.

Another small effect is the start cartridge (maximum two ;) as realty...
Jet aircraft of 50-60 years often used a pyrotechnic cartridge to start the engine, the same technique was also used for radial engines. The effect was short of spectacular, and only rarely was filmed, but in this reproduction of the FIAT G91R4 for Flightgear we wanted to include.



Too often the FGFs planes are "ugly" and often fly so far from reality and that I'm sorry. It would be better that a programmer did only a few planes, but well, with care! Such as the group of "X-Plane" working on excellent airplane with freeware license.

Last edited by abassign on Mon May 30, 2016 10:04 pm, edited 1 time in total.
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Re: FIAT G91-R (Gina) - JSBSim

Postby wlbragg » Mon May 30, 2016 9:59 pm

abassign wrote in Mon May 30, 2016 9:46 pm:The lights are my pride, a 3D model so nice finally deserves as I see the lights of FSX or X-Plane, or that look like the reality and not to be stellar effects like Hollywood! I would like that other programmers do the same for excellent airplanes like the C172P

I'm not sure I understand what your saying. Do you like the ALS lights or dislike them? The c172p is using the ALS lights.
But either way, I agree, you have a very nice looking aircraft.
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Re: FIAT G91-R (Gina) - JSBSim

Postby abassign » Mon May 30, 2016 10:40 pm

wlbragg wrote in Mon May 30, 2016 9:59 pm:I'm not sure I understand what your saying. Do you like the ALS lights or dislike them? The c172p is using the ALS lights.
But either way, I agree, you have a very nice looking aircraft.


You know that I really like the C172P and is reading the code you are writing that I learn so many things! Obviously if you learn ... then apply and then you learn other things ... For example Cobe571 (The author of the 3D model) included in the lights, as in reality the bulb, the reflector and the color screen. Inserting for each specific configuration (the reflective screen I make it reflective, colored glass is colored and only the lamp is emitting the color I want ... The effect is very interesting. Then I post a rise / decrease effect brightness according to ambient (I also need to display / hide the exhaust gases) increase / I decrease the brightness. Then in front of all this I put the ALS effect, but very minimal and I need two things, first to give a glare effect and the second to make the lights visible at long distances, as in real life. Thorsen, between a mumble and another, has taught this technique to me. I did various tests until you see on the screen what you see in reality. and I must say that the effect has fascinated me and I would like to apply it to the C172P (but this should be done some 3D elements) at least to try. If you're interested I'll explain how to prepare 3D.

With a lot of outside light is dominant on the glass and is reflected away the glare effect:
Image

Night use of the ALS effect (the focus when there is little external light, it would be better to use the properties inserted in the effect, but it is too small, maybe in the future ...)
Image


At night, at a certain distance, the light is always visible. This is only possible through the ALS effect.
Image

I made a video to help explain it:

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Re: FIAT G91-R (Gina) - JSBSim

Postby wlbragg » Mon May 30, 2016 10:58 pm

@ abassign the video is marked "private", but I think I understand what you were saying. Maybe I can look at your code at some point in the future and see exactly what your doing.
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Re: FIAT G91-R (Gina) - JSBSim

Postby abassign » Tue May 31, 2016 12:10 am

wlbragg wrote in Mon May 30, 2016 10:58 pm:@ abassign the video is marked "private", but I think I understand what you were saying. Maybe I can look at your code at some point in the future and see exactly what your doing.


Now the video is ok :) sorry for the inconvenient
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Re: FIAT G91-R (Gina) - JSBSim

Postby Thorsten » Tue May 31, 2016 4:52 am

Then I post a rise / decrease effect brightness according to ambient (I also need to display / hide the exhaust gases) increase / I decrease the brightness.


For the record - I think this is an artistic technique and not reflecting reality (it may reflect photography which works different from the eye at low lighting).

The true emitted light intensity of objects does not change with ambient light, if the mapping between true intensity and rgb value is done with a consistent model, your eye should take care of that based on scene illumination - to change the rgb value introduces a double counting.

See Richard's comparison of the F-15 exhaust at day and night posted in the ALS technical notes.

So while I may have taught you the technicalities of it, I actually advise anyone against doing it in that way - the ALS philosophy is more physics and less artistry. But it's your aircraft of course.
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Re: FIAT G91-R (Gina) - JSBSim

Postby abassign » Fri Jun 03, 2016 8:39 pm

The G91R4 going to have more fine landing gear, there is still a lot of work because the facts are the internal compartments and then configured the movements of the different axes. Our desired is to do, such as quality, a landing gear similar to that of the A10.

Image

However, a good 3D model requires hundreds of hours of work!
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Re: FIAT G91-R (Gina) - JSBSim

Postby abassign » Sun Jun 05, 2016 6:22 pm

The FIAT G91R has had several prototypes, all in aluminum color, so, given the quality of the 3D I decided to make a version without livery. This also allows to better see any defects on the surface, especially in areas of the fittings.
The problem is that the reflective surfaces are very dark in the shadow areas:

Image

I do not know if there are better ways to solve the problem of what I had adopted (if any would be very grateful that I was reported), now here I describe the technique:

Code: Select all
  <animation>
    <type>material</type>
    <object-name>Fuselage</object-name>
    ...
    <property-base>sim/model/livery</property-base>
    <texture-prop>G91R4-texture</texture-prop>
    <texture>Liveries/G91R4.png</texture>
    <emission>   
      <red>1</red>   
      <green>1</green>   
      <blue>1</blue>
      <factor-prop>/rendering/scene/ambient/red</factor-prop>
    </emission>
    <shininess>127</shininess>
  </animation>


As can be seen it was introduced an emission parameter proportional to the ambient light:

Code: Select all
    <emission>   
      <red>1</red>   
      <green>1</green>   
      <blue>1</blue>
      <factor-prop>/rendering/scene/ambient/red</factor-prop>
    </emission>


The "<factor-prop>/rendering/scene/ambient/red</factor-prop>" it reduces the emission value at a fraction of the value, so that the night the plane is not visible! The result is very good and avoid the presence of overly harsh shadows, giving the aircraft a very realistic look.

Image

This is another example in flight, in a shaded area:

Image

This is a picture, of the aircraft aluminum version ...

Image
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Re: FIAT G91-R (Gina) - JSBSim

Postby Thorsten » Mon Jun 06, 2016 5:00 am

The problem is that the reflective surfaces are very dark in the shadow areas:


That'd be because there is not much light reaching these surfaces.

If you look without an atmosphere, surfaces with a normal pointing away from the sun look near pitch black:

Image

If you're in the atmosphere, light scattered by the atmosphere lights up the surfaces which are not directly illuminated - the amount of light you get randomly scattered around relative to the directional light depends on haze and cloud coverage - on a clear day, you get hard shadows, on a hazy day you get very soft shadows.

The difference in illuminance between direct sunlight and shaded surface is easily a factor 100 on a clear day - that's significant even under the perception log. You visually very easily see the difference between hard and soft shadows dependent on weather.

The renderer knows all of that and consequently gives you dark surfaces when there is little ambient light - so the first screenshot is correct, the others are plainly not and much work has gone into avoiding such unrealistic lighting.

As can be seen it was introduced an emission parameter proportional to the ambient light:


This basically guarantees your next complaint that the renderer shows your plane far too bright in overcast skies and haze. But you're on your own with this - if you don't understand how lighting works and what an ambient light channel is to the degree that you introduce emissive animations of non-emissive surfaces during the day, you break ALS to a degree that just can't be supported any more.

Not to mention the breakage for the classic renderer and Rembrandt...
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Re: FIAT G91-R (Gina) - JSBSim

Postby erik » Mon Jun 06, 2016 7:25 am

Thorsten is right, if you look at this picture you will see that the original color was not far off:
Image

I think you would be better off by tweaking the models ambient color value a bit.

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Re: FIAT G91-R (Gina) - JSBSim

Postby abassign » Mon Jun 06, 2016 9:12 am

@Thorsten
@erik

Image
Albert Einstein had his Nobel prize for the photoelectric effect, or for a theory that would explain why so physically correct a metal body (conductive) re-emits photons (https://en.wikipedia.org/wiki/Photoelectric_effect), unlike the non-conductive bodies which color is due to absorption of photons, the conductive bodies re-emit them at a percentage which is depending on the efficiency of the process.
This means that the use of the re-emission of the simulation method is from the point of view exactly what happens in reality. The parameter 1 used is certainly high (normally is 0.85 to 0.95), but it is simply linked to the parameter used for the diffused light.
If you were in space, where the scattered light is small and only in the vicinity of a celestial body (albedo), I agree with you ... and I think that the shuttle reproduces quite well the reality.
The fact that the plane's shadow is too dark without the fix I've done is due to a problem of perception of the eye-brain system.
On this subject @Thorsten still do not understand, and I think it's a big problem that severely limits the quality of work. The eye-brain system is NOT a camera! As I have explained many times, the brain sees reality in a very different manner, and compensates the contrasts exalting the shadows and reducing the high-lights. The reason is born by biological evolution and the need to live in high-contrast environments such as tropical forests (by which we come) and still live our closest cousins (the primates).
In a simulator must build the reality which sees a camera or the eye sees the pilot ?
Personally I prefer the pilot eye not the camera eye ;)
And therefore I can assure you, at least you do not suffer from particular eye disease, that in reality the eye "flattens" the image through a complex scanning mechanism and local assessment taking advantage of the fact that the high-resolution vision is only a few square degree, compared to hundreds of square degrees that we think we see through a subsequent reworking.
I would not like to return to after burning discussion a few months ago ... Which it was linked to my perplexity to see what he sees a camera and not the eye of a human being who does not see the infrared!
Here, thank God, there is Albert Einstein who gives me reason ... and I think more and more that not always what is believed is the truth ...
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Re: FIAT G91-R (Gina) - JSBSim

Postby erik » Mon Jun 06, 2016 9:29 am

What happens to the ambient part of a reflective fuselage is that it reflects highly reflective surfaces which face the reflective fuselage. For example, a white sheet of paper facing the sun will get reflected by the ambient part of the reflective fuselage. But nothing else.

Without ray-tracing techniques it is impossible to know about such surfaces which would be reflected in the fuselage. By adding an emissive value you basically assumes it will reflect everything equally bright. Which isn't the case. In fact, most surfaces in the ambient side will not reflect anything because they are not reflective enough, or just to far away (which happens a lot when you are flying around).

If the reflective shader-effect works the way I think it works then increasing the ambient color slightly would be enough.

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Re: FIAT G91-R (Gina) - JSBSim

Postby Thorsten » Mon Jun 06, 2016 10:34 am

Albert Einstein had his Nobel prize for the photoelectric effect, or for a theory that would explain why so physically correct a metal body (conductive) re-emits photon


He'd be a bit depressed reading this... The article you linked clearly says it:

The photoelectric effect or photoemission is the production of electrons or other free carriers when light shines upon a material.

Electrons - not photons.

the conductive bodies re-emit them at a percentage which is depending on the efficiency of the process.


Yes, light can be reflected.

This means that the use of the re-emission of the simulation method is from the point of view exactly what happens in reality.


No, because re-emission of incoming light (reflection) is encoded in the ambient, diffuse and specular light channels. Only genuine emission of light independent of incident light goes into the emissive channel.

The eye-brain system is NOT a camera!


It's nice that you finally acknowledge that. A handful of people including myself has been trying to tell you that a few times after you kept posting screenshots of afterburner flames in low light that they do not represent correctly what the eye sees. We've known this all along, just you insisted differently.

And therefore I can assure you, at least you do not suffer from particular eye disease, that in reality the eye "flattens" the image through a complex scanning mechanism


Yes - which is why ALS passes light intensities through a perception filter and you don't see shadows a hundred times darker than lit surfaces (which is how the measured the light intensity differs) but a lot less.
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Re: FIAT G91-R (Gina) - JSBSim

Postby Thorsten » Mon Jun 06, 2016 10:38 am

In case you're interested in ambient light in reality vs rendering, may I recommend the section

Lighting beyond Blinn-Phong in my GLSL tutorial?
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