Tracers

[choctaw111]

This is not a troll or meant to start some heated debate.

I also posted this in the weapons forum but thought that it should go here instead.

I run this sim at a steady 60 fps with v-sync on and the tracer visuals are not correct.

At 60 fps, a projectile moving at 2,700 fps will travel 45 feet in 1/60 of a second.  The tracer should have the appearance of being 45 feet long but in game is only 6 feet long.

 

Cliffs of Dover had this correct.  It even changed the tracer appearance (meaning the apparent length of the tracer) depending on game speed, running at 1/2 speed, 1/4 speed, 1/16 speed, etc and even showed the tracers as "dots" when the game was paused.  It even showed the individual propeller blades! That was a very well done feature and is missing in BoS.

 

The colors of some of the tracers are not correct either.  Why are the ShKAS tracers orange in color?  They should be green.

 

The rest of the sims visuals are brilliant to include the nice muzzle flashes and I love the overall feeling of flying around is BoS but firing the guns is a disappointment.

[Lensman]

I'm not clued up enough to comment on the validity of your claim (but it seems very plausible) however you might be interested in this thread.

[Manfromx]

I was under the impression that what we see in photos and film isn't how tracers would look in person due to exposure times giving that distinctive long tail. Nothing I can confirm myself however.

 

Any gun aficionados or service persons that can comment on that? Genuinely curious even outside the context of the game

[dkoor]

Lasers! 

[Lensman]

I'll just mention this and then depart:

 

Sparkler's trail effect

--------------------------

The sparkler's trail effect occurs when one waves around a lit sparkler, creating a trail of light. Although it appears that this trail is created by the light left from the sparkler as it is waved through the air, there is, in fact, no light along this trail. The lighted trail is a creation of the mind, which retains a perception of the sparkler's light for a fraction of a second in sensory memory.

Edited October 30, 2014 by Lensman

[choctaw111]

I was under the impression that what we see in photos and film isn't how tracers would look in person due to exposure times giving that distinctive long tail. Nothing I can confirm myself however.

 

Any gun aficionados or service persons that can comment on that? Genuinely curious even outside the context of the game

I AM a service member from the 82nd Airborne Division.  Tracers do look like lasers.  When you speak of exposure time, the exposure time for a typical PC display is 60 frames per second.  At 60 frames per second, a tracer that travels at 2,700 feet per second would travel 45 feet for each frame rendered at 60 frames per second.  The tracer will appear as a line 45 feet long, not 6 feet as we have in game.

There are some very good videos on youtube that accurately show what a tracer looks like in flight but there are also some low quality vids as well that do NOT show its appearance very well.

I'll just mention this and then depart:

 

Sparkler's trail effect

--------------------------

The sparkler's trail effect occurs when one waves around a lit sparkler, creating a trail of light. Although it appears that this trail is created by the light left from the sparkler as it is waved through the air, there is, in fact, no light along this trail. The lighted trail is a creation of the mind, which retains a perception of the sparkler's light for a fraction of a second in sensory memory.

This is one of the reasons why tracers look like lasers and not just a spot.  Our eyes cannot detect a bright, fast moving spot as just a spot, but rather a streak.

[39bn_pavig]

Your eye isn't a camera, so tracer length isn't a product of fps.

[steppenwolf]

[BraveSirRobin]

I don't think they're trying to simulate what you see at 60 fps.  

[choctaw111]

Your eye isn't a camera, so tracer length isn't a product of fps.

If you have seen tracers in real life then comment away.  Cliffs of Dover got it right.  BoS is wrong. 

[=AVG=Zombie]

[choctaw111]

I don't think they're trying to simulate what you see at 60 fps.  

Then what are they trying to simulate?  Seeing a tracer from a perpendicular angle will have an appearance of more than 6 feet in length.  This is something that almost every game or sim gets wrong.  Then CoD comes along and they finally get it right only to its successor go back to being wrong again.

[BraveSirRobin]

Then what are they trying to simulate?  Seeing a tracer from a perpendicular angle will have an appearance of more than 6 feet in length.  This is something that almost every game or sim gets wrong.  Then CoD comes along and they finally get it right only to its successor go back to being wrong again.

 

How long does it appear?  And is that length the same no matter how far away you are and the velocity of the tracer?

[choctaw111]

How long does it appear?  And is that length the same no matter how far away you are and the velocity of the tracer?

This is a good question.  The apparent tracer length is dependent on speed.  It doesn't matter how far away you are this effect will always apply but will change with the angle at which the tracer is being viewed.  Directly from behind will appear as a glowing dot.  A tracer travelling perpendicular to your view will appear as a laser like line.  Imagine a bright, glowing rod that is approximately 45 feet long (based on what our eyes would see for a tracer traveling at 2,700 feet per second) but only a 1/4 inch in diameter.  Directly from behind it will appear as only a small circle but the more you view this "rod" or tracer from the side, the longer it appears to be.  This is how the tracers in game should be rendered.

[Matt]

The explanation is correct, but i guess since all these "looks like lasers!" comments came up on the CloD forums (and now even here), they are gonna keep it this way. Maybe it can be modded somehow and then people will actually see it in action.

 

What everyone can agree on i hope, is that the tracer of the ShKas is incorrect (same for MG151, MG17, UB) and should be fixed eventually.

[39bn_pavig]

Persistence of vision tracer length is not a product purely of how fast it is traveling and the angle of view, it is also a product of how far away it is, and thus the angle across your field of view. If you see tracers from far away they are covering only a small distance across your field of view in the same time, so will have shorter tails due to persistence of vision. They will of course cover the same distance in the same time, but have shorter tails as they appear to be moving slower. Given that view distances are so long - in the hundreds if not thousands of meters - it is reasonable that most of the time when we are seeing tracer fire they would not appear like lasers. At least not on an individual frame - persistence of vision fills in the line by interpolating frames in sequence. This is not the "sparkler effect" which is due to overloading cells in the eye to produce an after image.

[Manfromx]

Sounds like a good solution requires simulating a lot of different interactions, a simple long texture wouldn't be accurate either then.

[39bn_pavig]

At closer ranges the apparent speed of tracer fire would be much longer as it would be moving rapidly enough to invoke iconic memory in the eye - this has been measured at about 150ms response time, so from very close looking at tracer fire passing at 90 degrees it may look up to 400 ft long. So that's pretty much a laser. With distance and angle however, the trace would shorten considerably (and non-linearly) as it passed between direct stimulation of the retina (first order iconic memory) and interpretation by the visual cortex (2nd order). Add to that the complexity of how we perceive persistent images on a monitor and it gets complicated pretty quick.

[Heliocon]

Persistence of vision tracer length is not a product purely of how fast it is traveling and the angle of view, it is also a product of how far away it is, and thus the angle across your field of view. If you see tracers from far away they are covering only a small distance across your field of view in the same time, so will have shorter tails due to persistence of vision. They will of course cover the same distance in the same time, but have shorter tails as they appear to be moving slower. Given that view distances are so long - in the hundreds if not thousands of meters - it is reasonable that most of the time when we are seeing tracer fire they would not appear like lasers. At least not on an individual frame - persistence of vision fills in the line by interpolating frames in sequence. This is not the "sparkler effect" which is due to overloading cells in the eye to produce an after image.

Nailed it, and this was the one thing clod messed up with the tracers.

[Lensman]

Persistence of vision tracer length is not a product purely of how fast it is traveling and the angle of view, it is also a product of how far away it is, and thus the angle across your field of view. If you see tracers from far away they are covering only a small distance across your field of view in the same time, so will have shorter tails due to persistence of vision. They will of course cover the same distance in the same time, but have shorter tails as they appear to be moving slower. Given that view distances are so long - in the hundreds if not thousands of meters - it is reasonable that most of the time when we are seeing tracer fire they would not appear like lasers. At least not on an individual frame - persistence of vision fills in the line by interpolating frames in sequence. This is not the "sparkler effect" which is due to overloading cells in the eye to produce an after image.

 

That sounds entirely plausible.

[39bn_pavig]

Yup. From what i've seen the distance falloff for tracer length in CloD was underdone, but also I think the tracer length of some distant fire in BoS is underdone as well. When you see ground fire which is far enough away that the shells appear to be travelling slowly their tails are too long. Not as bad as CloD but still a bit too hollywood. Given the inverse square law they shouldn't be bright enough to burn your retinas to produce a trail, and they're certainly moving slower across the visual field than the tail length (via iconic memory) justifies.

 

Though I'm speaking purely about human visual processing here. I don't know if those shells actually do let out a trail of phosphors behind them or something. Maybe it's an actual thing we're seeing rather than an optical illusion.

Edited October 30, 2014 by 39bn_pavig

[choctaw111]

Yup. From what i've seen the distance falloff for tracer length in CloD was underdone, but also I think the tracer length of some distant fire in BoS is underdone as well. When you see ground fire which is far enough away that the shells appear to be travelling slowly their tails are too long. Not as bad as CloD but still a bit too hollywood. Given the inverse square law they shouldn't be bright enough to burn your retinas to produce a trail, and they're certainly moving slower across the visual field than the tail length (via iconic memory) justifies.

 

Though I'm speaking purely about human visual processing here. I don't know if those shells actually do let out a trail of phosphors behind them or something. Maybe it's an actual thing we're seeing rather than an optical illusion.

There is some smoke in the tracer trail and that is modeled fairly well in BoS.  Tracers, even when viewed at 90 degrees from very far away, are only dots with no trails.  It's the close up tracers having the longer trails that BoS does not do well at all.  That is what I was trying to illustrate in the photos in my original post.