U-Boot Periscope Telemeters

[diego_gut]

Originally Posted by Nikdunaev

Sorry, I am not sure I understand what you are saying

The optical magnification in telescopes is increasing the apparent angular size of an object by a certain factor, compared to what would be seen by the naked eye.
The decrease in field of view, looking through the same eyepiece, is a direct consequence of that, right?

So, it seems that zoom and field of view are proportionally linked to each other by definition.
If not, than the magnification power number is just meaningless.

In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.


In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.


To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.


What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.


Regards

[derstosstrupp]

Originally Posted by diego_gut

In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.


In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.


To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.


What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.


Regards

This makes sense. To be sure I rechecked the C/2 manual I have and it indeed only recommends using the graticle at 1.5x.

[John Pancoast]

Originally Posted by diego_gut

In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.


In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.


To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.


What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.


Regards

Many times, adding the "historical" figures into a game for most anything causes more problems than it solves.

[Efshapo]

Originally Posted by diego_gut

In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.

Hi, sorry to dig up the past but I'm doing some research about periscope fidelity in games.

If the magnification ratio is exactly 4 indeed, I think it's actually possible to get a graticle calibrated for both zoom levels. The field of view wouldn't interfere with the graticle use (it would just mask some ticks that are on the border).

The ratio between fields of view can be different from the ratio between magnification factors. It just means the vignette effect will be different.

Here is an illustration of what I think the observer would see:

Notice that the image disc diameter is smaller at 6x.

What do you guys think?

EDIT:

Originally Posted by diego_gut

What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.

What you say is that you used the 6x 2D layout for the 1.5x mode? That would mean the in-game vignette is exaggerated for the 1.5x mode. Did I get this right?

[Efshapo]

Here are my findings so far:

[John Pancoast]

Originally Posted by Efshapo

Here are my findings so far:

Interesting info. to be sure. But I'm not sure a "wrong" this or that is strictly correct.
Real world vs. computer screen, etc.
I'm more of a fan of does something work in the game to simulate it's subject vs. strictly historical specs, etc.
To often, plugging in historical performance specs of equipment, weapons, etc. (which many times are inaccurate anyway, being based on lab specs vs. real world use) causes more problems than it solves in a computer simulation of such. Many times, putting in historical specs for x, breaks function y of some other system, weapon, etc. in a game that was designed to work with the original specs of x.
What is more important is how does it perform in the sim, especially in the "big picture" of the entire sim.
I.e., iirc, GWX's attack scope had a mag of 10x. Historically correct ? No. But a good idea for the limited view of a computer game ? I think so.
Another example is the "pinpoint accuracy" of depth charges originally found in SH3. Historically correct ? No. But it helps make up for the dumb as bricks AI escorts and poor damage modeling. I like it myself, even with the sensor/damage model work since done to the original game, and it's actually not difficult to escape from anyway.

[Efshapo]

Here's how Wolfpack could be corrected to get a historically accurate field of view (current game state on the left, my correction on the right):

[Efshapo]

And here's how I would correct the reticle (images on the right):


I added a row to my table to check that all fidelity criteria were met:

[propbeanie]

I don't see SH4's Fall of the Rising Sun Ultimate (FotRSU) listed there... - Sure, they're US submarines, but the periscopes were done by CapnScurvy, based upon his "optical" investigations, and are basically what he did for his Optical Targeting Correction mod for SH4, but without the "Centered" conning tower. He did quite a bit of research work on his mod... and posted it all in a thread... which I cannot find. If I can find the thread, I'll link you to it. It is full of all of his findings, and how he tested...

[ybar]

Originally Posted by John Pancoast

Real world vs. computer screen, etc.
I'm more of a fan of does something work in the game to simulate it's subject vs. strictly historical specs, etc.

It's a shame if we have to move away from reality to adapt a simulator to a computer game ...
Out of curiosity, I can't wait to see how "Crush Depth" will handle this.

I don't know which eyepieces were placed on the Uboote.
But I am almost convinced that the engineers of ZEISS, have placed "wide angle".
I use a terrestrial telescope to watch the birds, and I use an eyepiece of this type (for the same zoom level, the panorama can be seen better)
On our French forum, a member with a refracting telescope has also just confirmed his change from the inexpensive eyepiece to a wide-angle eyepiece.

[John Pancoast]

Originally Posted by ybar

It's a shame if we have to move away from reality to adapt a simulator to a computer game ...
Out of curiosity, I can't wait to see how "Crush Depth" will handle this.

I don't know which eyepieces were placed on the Uboote.
But I am almost convinced that the engineers of ZEISS, have placed "wide angle".
I use a terrestrial telescope to watch the birds, and I use an eyepiece of this type (for the same zoom level, the panorama can be seen better)
On our French forum, a member with a refracting telescope has also just confirmed his change from the inexpensive eyepiece to a wide-angle eyepiece.

A shame ? Not at all. It's on a pc; by it's very nature it's not realistic.

[Efshapo]

Originally Posted by John Pancoast

I'm not sure a "wrong" this or that is strictly correct.
Real world vs. computer screen, etc.
I'm more of a fan of does something work in the game to simulate it's subject vs. strictly historical specs, etc.
To often, plugging in historical performance specs of equipment, weapons, etc. (which many times are inaccurate anyway, being based on lab specs vs. real world use) causes more problems than it solves in a computer simulation of such. Many times, putting in historical specs for x, breaks function y of some other system, weapon, etc. in a game that was designed to work with the original specs of x.
What is more important is how does it perform in the sim, especially in the "big picture" of the entire sim.
I.e., iirc, GWX's attack scope had a mag of 10x. Historically correct ? No. But a good idea for the limited view of a computer game ? I think so.
Another example is the "pinpoint accuracy" of depth charges originally found in SH3. Historically correct ? No. But it helps make up for the dumb as bricks AI escorts and poor damage modeling. I like it myself, even with the sensor/damage model work since done to the original game, and it's actually not difficult to escape from anyway.

Well, "wrong" is not subjective here since we're talking about a game of the simulation genre. The game is either "right" (historically accurate), or it is not.

The magnification I'm talking about in my table is only related to the field of view (the one restricted by the vignette effect, not the in-game FOV), it is not related to the player screen size. There is no way for the devs to control that (unless they add a slider in the setting screen for a kind of "magnifying glass" effect). About that 10x magnification in GWX, I don't see how it could have been computed given what I just said, but I agree that the bigger the ship on screen the better the gameplay: I did the math and found out that for the magnification to be optically accurate, I had to stand as close as 38 cm from my 27" display! And Wolfpack devs actually did an amazing job at that by having chosen to ditch the upper and lower parts of the image circle so it can appear bigger.

Considering your expressed concerns, I haven't found how those modifications would break any current gameplay mechanics. Did you have something specific in mind?

[diego_gut]

Hello,


Sorry for the late response.


What I did was to make the graticle for 1.5x zoom as in real life but it is calibrated for 6x too. That is, if a ship measures 2 degrees using 1.5x, it will measure 8 degrees using 6x zoom. The same applies for the vertical scale.


The graticle in DGUI uses milliradians but the graticle in DGUI Hardcore uses angular radians (16 per degree instead of 17.45) as in real life. I even included real life tables that you can use to convert to distance.


Regards,
Diego

[Efshapo]

Originally Posted by diego_gut

What I did was to make the graticle for 1.5x zoom as in real life but it is calibrated for 6x too. That is, if a ship measures 2 degrees using 1.5x, it will measure 8 degrees using 6x zoom. The same applies for the vertical scale.

Of course the magnification ratio should be exactly 4, that's the minimum required!
As you can see in my table, the only game that does not respect that is Uboat.

Originally Posted by diego_gut

The graticle in DGUI uses milliradians but the graticle in DGUI Hardcore uses angular radians (16 per degree instead of 17.45) as in real life. I even included real life tables that you can use to convert to distance.

Sure, but my question was about the vignette (the dark circle around the image). If you use the same image displayed at the same scale on screen for the graticle (as you should), a 9° and 36° FOV means you also used the same vignette. To correct for the 1.5x one and make it 38°, you just have to make a dedicated vignette with a slightly bigger diameter. That's what I meant.

[John Pancoast]

Originally Posted by Efshapo

Well, "wrong" is not subjective here since we're talking about a game of the simulation genre. The game is either "right" (historically accurate), or it is not.

The magnification I'm talking about in my table is only related to the field of view (the one restricted by the vignette effect, not the in-game FOV), it is not related to the player screen size. There is no way for the devs to control that (unless they add a slider in the setting screen for a kind of "magnifying glass" effect). About that 10x magnification in GWX, I don't see how it could have been computed given what I just said, but I agree that the bigger the ship on screen the better the gameplay: I did the math and found out that for the magnification to be optically accurate, I had to stand as close as 38 cm from my 27" display! And Wolfpack devs actually did an amazing job at that by having chosen to ditch the upper and lower parts of the image circle so it can appear bigger.

Considering your expressed concerns, I haven't found how those modifications would break any current gameplay mechanics. Did you have something specific in mind?

My comments were general nature, not at your examples. I'm of the opinion that "historically accurate" does not necessarily need, demand, nor require verbatim "historically accurate" figures, specs, etc. to be used, for "historically accurate" and "right" results to occur.

Your mileage may differ.