Widescreen Gaming Forum

Hey everyone, this has been something that I have been struggling to get my head around for years, and its gotten to the point where I figured eh, I might as well ask. And since im getting 3x1080p soon, I know if I dont figure this out I'm going to go mad =]
Essentially, I'd like to know a few differences between terms. Im going to write what I believe to be the right thing, and If possible I'd like it if anyone could correct me where I'm wrong. I've bolded all the main terms, mainly for my own benefit so I can make sure I'm being as clear as possible. I don't know if these are the right terms, but I will be consistent in their use.

One of the biggest I always hear about is the Angle of View. Now, I know this is the number of degrees that can be seen from the cameras current position. For example, 90 means the left hand side to the right hand side is a cone of 90 degrees from the current camera.
I know this applies to horizontal, but also vertical. When changing the FoV in the source engine, I notice that you can see more on the top and bottom of the screen, making changing the FoV, (not the angle,) act as if you are zooming in or out. Therefore, in this case, changing the FoV changes both the Hor and Vert Angle of View.
Now, with most 3D games, since the camera is viewing the game in a human eye like perspective, the edges of the larger angle of view get "fisheyed", in the sense that they display less relative space over the same area the further towards the edges you go. My best example of this is World of Warcraft. Adding more monitors changes the angle of view on the horizontal, but not on the vertical, resulting in more of the game being shown. However, on the left and right monitors, the game looks stretched due to this. Am I right in believing that this fisheye like effect is a type of perspective?
Am I also right in believing that the less horizontal screen space, with the same angle of view, the less severe the stretching, but the more severe the compression? Would anyone be able to give me an example of something with a fixed vertical and horizontal Angle of View, with an aspect ratio of 48:9 and also with a ratio of 16:9? I'm guessing that while you will be able to see exactly the same amount of stuff on the screen, the 16:9 one will look a lot more compressed relative to the 48:9 one. (Actually, come to think of it, is it the same as displaying a 4:3 resolution on a 16:9 monitor? as in, everything gets stretched relative when you go onto the 16:9 even though you can see the same amount of the game)
Also related to that; Does increasing the Vert Angle change how fisheyed the sides are horizontally, or does it just sort add more vision to the top and bottom? If someone could give me some comparison pics like that, I'd really appreciate it. I'm guessing not, but It's hard to visualize with no reference.

Now, another line of confusion has arisen from Diablo 3 and Torchlight 2. With these games, there is no fisheye effect at all, and effectively in my mind the camera is really long. Rather than the camera being a point, it extends along the horizontal so that everything is viewed with the same perspective. Am I right in believing that this is an isometric perspective? and am I right in thinking that an isometric perspective does not have an angle of view, only a vewing angle? (as in, the angle you are at relative to the scene, not the angle of the things you can see relative to you)
Am I right with this; an example of both of these, three boxes. One on each screen. The camera is sitting on the floor, looking at the middle box dead on. only the front face is viewable.
In the fisheye perspective, you see the front face of the middle box on the centre monitor, the right and front faces on the left hand monitor, and the left and front faces on the right hand monitor. On the two side monitors, the view is distorted.
In the Isometric perspective, all three boxes are displayed exactly the same, only being able to see the front faces.

I know that there are different types of isometric, such as side on, top down, top down and angled, side on and angled, etc.
Am I right in believing that the Isometric perspective does not have a vanishing point, and that that is the key difference? For example, in a top down 45 degree isometric game, (my example would be rollercoaster tycoon,) you can essentially follow the grid lines on the ground forever. if I was to put myself in that world with the standard fisheye camera and stand in one of the squares, the lines would eventually meet at a vanishing point in the distance, much like train tracks.
Am I right in thinking this can also be applied to all old 2D platform games? since they are side on with no distortion, if you were to pull the sides of your monitor out you would see more of the level, but it would not be distorted at all. (This is a good example of what I mean, http://ian-albert.com/games/super_mario_bros_maps/mario-1-1.gif)
My only example of a game that includes both that I can think of is Super Paper Mario. In 2D, you have the side on isometric perspective since there is no vanishing point, and in 3D, you can clearly see a vanishing point. Am I right in thinking that If you were to use the 3d camera for the side on view, you would be able to see the sides of blocks on the right and left hand sides of the screen, since it's fisheyed? e.g, when you look into a tunnel in real life you can see both walls of the tunnel.

Going back to D3/TL2, is this an isometric camera perspective? if you think about it, it's the same as say rollercoaster tycoon. the more you add to the size of your screen, the more of the world on the left or right hand side you can see. If you move the camera to the side in RCT, nothing gets distorted when it gets to the edges, if you move yourself to the side on D3, nothing gets distorted at the edges.

My last few questions;
What is the correct term for what I am referring to as fisheyed?
What is the correct term for what I am referring to as Isometric?
When you zoom in on a game (with ironsights) Does that change the FoV to be something lower, therefore reducing your Hor and Vert Angle of view, resulting in a zoomed in effect?
In contrast, When you zoom in on something like World of Warcraft, does that move the physical location of the camera while not changing the Hor/Vert Angle of View at all?
Are RTS games the main genre that always use an isometric camera?
What is the reccomended angle of view for 4:3, 16:10, 16:9, and 48:9? (where 48:9 is three 16:9 monitors)
Am I mostly right with what I am saying or have I understood this completely wrong?

I know that was horribly rambly, but I don't know an easier way to put everything and this has driven me insane for years.
If anyone can help me understand the correct terms and correct me where I am wrong, I will massively, massively appreciate it.

Thank you!

Allow me to further confuse by making some shit up.

D3 and Torchlight do have the fisheye effect which happens both vertically and horizontally. It gets more noticeable with higher fovs and certain camera positions/angles. They are using calculated camera views for the vector graphics which is where the fisheye distortion comes from. It is easier to notice in certain games and aspect ratios. The witcher 1 always seemed like a good example of seeing both the horizontal and vertical distortion get worse the farther from camera center you look.

There is no distortion in SMB and the like, the rendering is just displayed art files.

Isometric is kind of an anachronism. Older RPGs used this to give depth and perspective to static art files. Like the first two fallouts. Nowadays it is used more to represent a camera position/angle used in games with vector graphics that look similiar to these older titles (but tend to suck).

Zooming in will lower the fov and vice versa. Games can move the camera position or change the fov or both. Think of changing the fov as using the zoom function on a camcorder. Think of changing the camera position as walking backwards or forwards while holding the same camcorder. Changing the camera position will change the perspective at which you see things. Changing the fov will increase or decrease the amount that you see while keeping the same perspective.

When a games lets you move the camera in and out like a dolly it is changing the camera position. When it uses gun sights and such it is changing the fov.

There is no correct fov, just correct behavior of fov. What may be desired to someone may be unplayable to another. It is game and user dependent. It is considered best for the fov to expand horizontally in unision with wider aspect ratios and vice versa.

I would guess it is a number of things. I think the camera being far away plus the way the it angles across things could make it less noticable. Also different users can be more sensitive to things like this.

The surround pics for Torchlight 2 show it fairly well on the left and right sides of the image.

http://www.wsgf.org/dr/torchlight-ii/en

Thanks for that answer, as you probably could guess I understood all of it except for the first paragraph. Well, the first bit of the first paragraph.
Since you say that D3/TL2 do have the "fisheye" effect, how come the distortion not noticeable, and it looks like there is no.. "point" that the camera is located? Is it just that (if you imagine the scene) the camera is physically reeealy far back, but the FoV is so small its zoomed, reducing the distortion?

EDIT: I figured out how to do this on my monitor, so this:




The second picture is 1438x200, so its stupidly wide.
What I noticed from the image is that diablo is effectively on a convex world, but I always thought all games showed with a concave camera. Now i've given it some thought, everything is convex. A fisheye lens gives a convex image, as everything bends away from the middle. For some reason, I thought everything bended towards, when it bends away.
Not that it really changes anything, just my perception.
Anyway, thankfully that image shows the fisheye effect in diablo 3, and I am just assuming its the FoV combined with the physical location of the camera in the scene combined with the viewing angle that creates the strange effect that looks like it doesn't fisheye. I suppose since the camera is physically so high up, if you were to get a 180 degree viewing angle, you would get a really massive amount of the world displayed.

Well, thankfully im learning! thank you!
I'd still appreciate any more explinations/perspectives (pardon the pun) on this, thanks!

Aah, indeed they do. From what I can figure, I'm guessing that D3 actually has a very low angle of view, but it must be that the camera is pretty far out. when going incredibly widescreen, it looks like the FoV is changed relative to that, so the middle screen stays exactly the same.

Well, that's definatley cleared that up a bit more in my head, thanks =]

I've got another question related to all this, after i've been doing a bit of reading.

What actually causes edge distortion?
I mean, does the human eye technically get edge distortion? is it just a thing due to how a lens works? why is it that things are essentially smaller the closer they are to the middle?

Why is it that panoramas tend to have distored straight lines, when extremely wide videogames do not?
What would happen if you changed how the camera worked so that in a 3d game it was effectively pixel based, and was always looking "forward" no matter how far to the left and right you got?

The problem I'm having is i'm finding it impossible to visualise.. is there any program that has a load of different camera modes that I could switch between so I can understand this better?

EDIT: I believe one of the terms i'm looking for here is rectilinear as opposed to isometric. At least, I think.

EDIT2: Aha! this: http://www.tawbaware.com/projections.htm website gives a good example, showing that a videogame is rectilinear. it shows that when you have a wide angle of view with a rectilinear projection, you get the distortion. Obviously lowering that angle reduces the distortion, but displays less of the content. Rectilinear keeps all straight lines straight, and thats the key point about it all.
Google street view is a good example, in that it is projecting a panorama image in a 360 degree cylindrical fashion, which is then being projected back in a rectilinear fashion. So, if you were to increase the street view angle of view, you would get edge distortion. Rectilinear is a way of displaying a curved image, (a lens is curved, and ultimatley produces a curved image) on a flat plane. Therefore, if you had a 180 degree curved monitor, you would want to use a cylindrical projection with an angle of view of 180 degrees. This would essentially match up the projection of the image with real life, and keeps straight lines straight due to the curve.
An example, take a 180 degree panorama. Most straight lines on it would curve upwards. However, put that image on a 180 degree curved surface, and that line is straight relative to the real world. as it goes off into the distance, it goes further towards the horizon, since that is the vanishing point.
I managed to understand this by printing off this image: http://upload.wikimedia.org/wikipedia/commons/5/5f/Chicago_Downtown_Panorama.jpg
This image has the barrier, which is curved on the image, but obviously would be straight in real life. If you curve the image around your head, as if the image was whats actually in front of you, that would appear straight in the physical plane. If you know what I mean. As I said, my best example is street view, thats all panoramas - yet there are no curved lines. If you were to uncurve that and spread one 360 degree panorama across your floor, everything would bend upwards weirdly.

GOD this is complicated :D

EDIT3: Also, what im calling isometric is an Orthographic camera. I think.
EDIT4: Yes, it is. Using the default game demo that comes with unity, i switched the camera from perspective to Orthographic at will, and it did exactly what I expected. It removed all distortion at the edges, and essentially removed all vanishing points.

Thank god, I've finally worked all this out.
:D