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Air to air in multiplayer aircraft drawing range

Roy Holmes

Roy Holmes

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Anyone know what the furthest range is at which another aircraft is rendered or becomes visible. I'm basically talking about AI in free flight and any aircraft in multiplayer.
One would think it could be a function of aircraft size, visibility light conditions and aircraft lighting. But might it also have something to do with LOD?
Roy
 
You need to set SmallPartRejectRadius = 0 on the cfg.

Then you could see them as far aa they are, but keep in mind the lods.


Enviado desde mi Nexus 5 mediante señales de humo.
 
The AI labels are visible when the AI is within 10nm of the user plane and they seem to always be visible before the plane is.

I wonder if variables like monitor resolution would change what one person sees as compared to another.

cheers,
Lane
 
Model visbility is, to large part, determined by its LODs.
LOD400 = model visible when the object is 400 pixel in size on screen
LOD200 = model visible when the object is 200 pixel in size on screen
LOD30 = model visible when the object is 30 pixel in size on screen

This is one of the reasons why MSFS always scaled well with screen resolution in terms of performance.

Combined with "SmallPartRejectRadius = 1" and appropriate LOD models you might have your objects visible at a considerable distance...or at least until FSX culls the object labels.


I can't remember the exact number, but I think the default player "bubble" for world rendering and AI tracking is 100 nm in radius.
 
Very interesting explanation about the LOD. Thank you.

I am surprised by SmallPartRejectRadius = 1. I have always thought that right value was 0, not 1.
 
Basezaragozavirtual said:
Hi Tisor, we are using smallpartrejectradious, but unable to get a good visual further than 2 nm. Any other idea?
Click to expand...
We just use that. Not sure a exact distance for the visibility we have achieved but for sure is more than 2nm.

Thing is in a 1920*1080 screen you may see only 5x5 pixel on an aircraft far away, so is hard to see, but it is there.

Depends also on the settings I think.
 
I did some multiplayer tests yesterday in P3D V3.2. The target aircraft used was Mirage F-1. Against a good contrast background I could just discern it as a black dot at about 2.75 nautical miles. I was aided by having a HUD target designation box placed around the visual return. I could not see it at 3 miles. Beyond 1.0 miles it was a blob, inside about 0.5 miles I could identify the type.

My monitor is operating at 1920 pixels in azimuth, it is 20 inches across and I sit at 30 inches from it. For this sortie the zoom was at 1.0.
The geometry gives a screen width of 63 degrees with 34 pixels per degree or 0.56 pixels per minute of arc. This means the visual acuity of the screen is equivalent to 20:40 (6:12) or about half normal.
So one would expect to discern aircraft on the screen at half the distance you would in real life. The F-1 is about the same size as a Hunter and I remember discerning those at 10 miles if they were not contrailing and about 15 under ideal conditions when trailing. Now that was back in the early 1960's and I did have good eyesight at the time. However my corrected eyesight is still 20:15 (6:4.5) so it is not an issue.
Note I had the zoom at 1.0. That takes a bit of getting used to and you must have something like Track-IR to do any kind of scan. But you can easily discover that at 0.5 zoom things are half size so their visual range will be half.

I found a Snellen acuity chart and scaled it for the geometry of my monitor
Snellen at 30 inches.jpg

The normal acuity line is number 8. It is not a really accurate test, but by my calculations the screen resolution and viewing geometry are such that line 7 is closer to normal and is about equivalent to 20:40 (6:12)

Ignoring LOD, the results I had are about what would be expected. But, if you operate at 0.5 zoom you should divide the ranges by 2.
Roy
 
I have one more question about LOD
If the external model was built with no LOD declared, what happens?
MCX gives it a LOD100 designation, but it is not made invisible in the sim at a range commensurate with LOD 100.
Does this mean that the sim just draws it increasingly smaller as range increases?
Roy
 
Roy Holmes said:
I have one more question about LOD
If the external model was built with no LOD declared, what happens?
MCX gives it a LOD100 designation, but it is not made invisible in the sim at a range commensurate with LOD 100.
Does this mean that the sim just draws it increasingly smaller as range increases?
Click to expand...

The model is rendered until it reches the pixel size determined by SmallPartRejectRadius (6 px by default or so). After that, it's not rendered anymore.

LODs are just a means of reducing scene complexity and the amount of triangles in the render pipeline. If you want to feel grateful for LOD rendering, give FlightGear a try. You'll need a supercomputer to run it at world detail levels comparable to FSX.
 
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