A need for a virtual camera thread

[Gary David Bouton]

Hi All--

I received some mail asking to open a thread on virtual cameras here. And I can see the reason why. We've all bootstrapped ourselves into modeling (I sincerely doubt anyone took lessons; I don't know of a school with "virtual cameras and modeling 101" on their curriculum).


Questions to be tossed out:

1.) What are the advantages of using a wide lens over an orthographic (axiometric)?
2.)How do you go about creating depth of field, what IS depth of field, and how does it affect your picture?
3.)Any limitations with current programs' cameras?


Me, myself, tend to use 2 different camera settings: I go wide angle to create dramatic scenes (20mm or so lens) (this is good for taking a boring box shape and making it look hefty), and when I want realism, I use 50mm, 'cause the human eye is around 50-55mm.


Info for our 3D brothers here, please!


Kindest Regards,

Gary David Bouton
Gary@GaryDavidBouton.com
Free education! The Writings Web site
and the updated GaryWorld Gallery is pretty okay, too.

[Gary David Bouton]

Hi All--

I received some mail asking to open a thread on virtual cameras here. And I can see the reason why. We've all bootstrapped ourselves into modeling (I sincerely doubt anyone took lessons; I don't know of a school with "virtual cameras and modeling 101" on their curriculum).


Questions to be tossed out:

1.) What are the advantages of using a wide lens over an orthographic (axiometric)?
2.)How do you go about creating depth of field, what IS depth of field, and how does it affect your picture?
3.)Any limitations with current programs' cameras?


Me, myself, tend to use 2 different camera settings: I go wide angle to create dramatic scenes (20mm or so lens) (this is good for taking a boring box shape and making it look hefty), and when I want realism, I use 50mm, 'cause the human eye is around 50-55mm.


Info for our 3D brothers here, please!


Kindest Regards,

Gary David Bouton
Gary@GaryDavidBouton.com
Free education! The Writings Web site
and the updated GaryWorld Gallery is pretty okay, too.

[Earl]

Hi Gary. I couldn't tell if you were looking for someone to answer these questions, or if you were just generally trying to bring the ideas up.

But regardless, here's an explaination of Depth of Field (I'm not a photographer, so it's my way of viewing it).

Depth of Field is a term used to describe the distance, both forward and backwards, from the focal point in which the image appears sharp or in focus. In the real world, the depth of field is controlled by the f-stop. The f-stop sets the diameter of the lens aperature, and thus affects both the brightness and the sharpness of the image. However, in most 3d programs, the f-stop only affects the sharpness.

Each 3d program is different, but most will give you two controls for Depth of Field. Focal Distance and F-Stop. The focal distance refers to the distance from your camera that appears in focus. If there is an object there, it will appear in focus. The lens focal length (a value set elsewhere in your camera properties) is then divided by the f-stop value to get the simulated aperature diameter. Therefore, higher f-stop values will results in great depths of field, while smaller f-stop values will result in smaller ranges for the area of focus.

Some 3d programs may not use realworld values and terms to control the depth of field, which could make it easier to adjust. However, for matching true camera lens settings, the real world values are a life saver.

So, in the end, Depth of Field basically means that there is a focus point to the image and anything before or after that begins to become out of focus - just like a real camera.

[jens g.r. benthien]

Gary,

the human eye has a viewing angle of approx. 58 mm for color, and between 20 and 35 (don't ask me about the hughe variation here) in b&w - in 'normal' situations.

When concentrating, the humans ** can ** expand the angle for the color a bit, but the outmost areas are kind of 'color aliased', that means the brain adds the colors to the b&w area, based on the overall color scheme in the scene.

Limitations? Not in Cinema 4D XL 7... even a few mm focal length works great, but it doesn't produce the 'real' fish eye effect.

About depth of field: Earl said it all and posted a great sample. What I might add is that the focal length - at least in real photography - is not symmetrical: let's assume the focus is at 3m, then the depth of field would range from (with a wide open aperture) from 2.5m to 4m - that means 1/3 extending to the camera and 2/3 extending to the background (physics of the optical rules).

That's my tiny contribution... I wish I had the time to browse my archive, but it's Saturday and one of the last beautiful summerdays up north...

Have a great weekend,

jens

jens g.r. benthien
designer
http://jens.highspeedweb.net

[Gary David Bouton]

Thanks Earl and all--

My idea originally was to set up a virtual "help desk"...users have a question/problem involving the use of a virtual camera, and one of us answers it.

It seems as though not a lot of people talk about or post images where the camera is the hero. We certainly have enough "model"-oriented people here! [img]/infopop/emoticons/icon_smile.gif[/img]

If you have a moment and did something unusual or beautiful (or both), please post the image and tell us how you did it.


TIA,

Gary David Bouton
Gary@GaryDavidBouton.com
Free education! The Writings Web site
and the updated GaryWorld Gallery is pretty okay, too.

[s.winders]

Thanks Gary/guys [img]/infopop/emoticons/icon_biggrin.gif[/img]


I am really green to virtual cameras and I made what I thought was a good scene with good modelling and lighting,but I wasnt really impressed with the camera result.I used a focus of 85 and dof of front and used the soft filter for rendering in Cnema 4ds render settings.


Oh ya I know the bottles look distorted and I am unsure if this is the camera or if I accidentally changed the round splines shape as I modelled them.

What camera settings would you guys use for a scene like this?

Cheers [img]/infopop/emoticons/icon_biggrin.gif[/img]

Stu.

[s.winders]

Heres the camera settings,also as you can see the splines are indeed still round so it must be an effect due to the camera setting?


Any ideas guys?


Thanks [img]/infopop/emoticons/icon_biggrin.gif[/img]

Stu.

[randyrives]

While I am very green concerning virtual camera's. (as I am still trying to learn to model well, so I could have something nice for the camera [img]/infopop/emoticons/icon_smile.gif[/img] ). I do have some experience with 35mm photography.

I usually use a wide angle for landscapes, and group photos, and interior shots. But wide angle lenes have distoration on objects that are close to the camera. They can also have unwanted effects on people (such as distorted the nose, making it look very large, and long).

For photographing people an 85-105 is a good choice. Of course anything longer 110-up is used only to bring a subject close enough to fill the frame, when the photographer is unalbe to get close enough to the subject himself.

So what setting should we use on our virtual camera? I think 50-85mm is good. A wider angle (28-35mm) can be used if we need to show a wider field of view while still filling the frame with our scene. I do not see a need (always exceptions) for any focal lenght over 105mm since we can get as close to our virtual objects as we want.

---Randy

[s.winders]

I tried a number of other lenses as well whilst rendering the same scene,but the distortion remained.The bottles are definitely round not oval...well this ones got me stumped [img]/infopop/emoticons/icon_rolleyes.gif[/img]

I suppose the distortion would go away if I zoomed in further but I like the depth just the way it is.There must be a way of getting rid of that distortion and keeping the depth.


Stu.

[Erik Heyninck]

I do make photographs, and use several lenses. When I read these entries, I see that 3D software imitates these opticaal lenses.

One of the basic rules of photography is that telelenses tend to flatten (think of Formula1 photos) and wide angle tends to exaggerate depth.

Except for the increasing depth of field with smaller F-values, the aberrations of a lens are also less visible.

These two practical problems (they do not occur in the theoretical model of a point-lens.) can be used to one's advantage.

Use tele's (the longer the better) to flatten your view, and use wide angle (up to 24, 20mm) to increase the feeling of depth. Therefore with a wide angle, you need a real foreground and a background. Example: the sea is the sea, but when you come close to a rock or a tree, and take that as foreground, you get a beautiful dramatic effect. When used in a room, for example, or to make portraits, the exaggeration becomes caricatural. This is the disadvantage.

As for the fish-eye: there are two types, the real fish-eye and the intermediate one.
Just like every tele narrows the width of the view (as compared to "normal" human view), the wide angle broadens it. And the fish-eye is an extreme wide-angle lens. So what happens? It is as if you see everything, left, right, up and down that is before (and a little behind) the perpendicular plane of your eye.
The intermediate fish-eye is created to behave like a normal wide angle lens outside the limits of what normal wide angle lenses can do. This is the fish eye I think one meets in the 3D programs.The circular deformation that is provoked by fish-eye lenses can be imitated with one of the effects in most bitmap programs.