Q: Field of Vision for Modeling?

[gnarlycranium]

I'm eager to hear the answer on this one, too. Being able to look at my model without distortion is a GOOD thing. Of course, when I put in perspective photos for reference, and try to match the FOV on those, that's a whole new barrel of monkeys... but having at least a default neutral human-eyeball-view would be nice.

The default in MAX is 45 degrees, I think.

[ceql]

Heya Gnarly Cranium, I'm glad I'm not the only one wondering about this ;)

hmmm, I've found the quote I was looking for...

Ok!! The quote from syomka is:


Just an advice: The human eye sees the picture with no
distortion within the limits of 36 degrees so check your model in camera view with no more than 36 degrees.


He also posts an orthographic view of his model, Anna, in the following post... thread is found @ http://www.cgtalk.com/showthread.php?threadid=14912&perpage=15&pagenumber=13

hmm... no more than 36 degrees!

However, it should be noted that too little Angle of View will make it become more orthographic, so what should the lowest number be? imho I've think 22 degrees is a little too orthographic, anywaz....


hrmmm I've been investigating this thing a little, and on my sister's Microsoft Dogs CD (funny where u find things! ;) ) there's a feature where they compare human vision to dog's vision and it had an interesting diagram...

http://users.bigpond.net.au/sequel/MSDogs.jpg [edit: Hey! my IMG tags don't work!]

Hmm, and that suggests that we have 45 degrees of [clear] vision...

Which, as Gnarly Cranium said, is the Max default... I've also noticed that the MAX viewport perspective feels more accurate than the Maya one.


You know what would be really kewl? If you could just model without perspective distortion / orthographically, and someone made a script that can distort the model to match any given distance / Angle of View. All it'd have to do is create a lattice box and calculate how far to move each point... altho I'm not good enough @ maths to work out how to do it :p


Anywayz, comments and ideas are more than welcome!

[cerreto]

actualy i find this to be a great post as it was a question i myself had a ways back i use lw the majority of the time and all i have is a slider rather than degrees which pisses me off anyway normaly i had it set to about half now it is in the lwer 3rd which to me seemed more natuaral strange that your research found it to be similar to what i must be using it at

[ceql]

I've actually got a similar thread in the Maya forum, asking about focal length (adjusting this will change the angle of view)

http://www.cgtalk.com/showthread.php?s=&threadid=40603
(hmm Sorry for effectively double-posting!)

quote from beaker:

Your eye is around a focal length of 65-70. I have no idea why maya's default camera is set to such a wide angle of 35.

focal length of 65-70 = angle of view between 30.96 - 28.84
(note that these are no greater than 36 degrees, either ;)

Thanks for the info beaker!

[ceql]

Hmmm, Note that when I make a conversion between Focal Length, and Angle of View, I am simply typing in one of the values inside of MAya, and Maya works out what the other value is...

So, if I type in Focal Length 50, Maya works out a 39.6 Angle of View.

Also, I'm gonna round off all the numbers as to make it easier to read... so, I'll assume Focal Length 50mm to be about a 40 deg Angle of View

--------

HowStuffWorks says:

50 focal length (40 degrees Angle of View) is closest to normal vision...

[it also recommends 105 focal length (19.5 degrees Angle of View) for Telephoto /zoomed-in closeups.]

src: http://www.howstuffworks.com/digital-camera8.htm

---------

Also, this page from dPreview.com I found off google

http://www.dpreview.com/learn/Glossary/Optical/Focal_length_01.htm says the same thing about the 50mm...

It says that our eyes see 46 degrees...

However!! The page says that 50mm gives an Angle of View of 46 degrees, which is incorrect if I do the consersion in Maya... 50mm is 40 degrees, not 46 degrees! afaik.

but I'll assume they recommend both 40 Degrees AND 46 degrees as normal.

---------

about.com says:


Camera Lens #1: Normal

The focal length of this camera lens is measured in millimeters and determines the lens's viewing angle. Camera lenses with a 35mm - 65mm viewing angle are called normal lenses. The most common normal lens is the 50mm. These camera lenses have a wide range of uses and are very popular. If you had to choose only one lens for your camera, a 50mm lens would serve you fairly well in most situations.



http://cameras.about.com/library/weekly/aabyb011502a.htm

So, in otherwords, anything from the ranges 54 degrees Angle of View (This is a max limit as this lens is also in the Wide Angle lens catagory) to 31 degrees Angle of View is considered normal, with around 40 degrees being closest to the eye.

---------



********************************************

Anywayz, a quick summary of the numbers I've gathered:

********************************************


AOV = Angle of View (Approx)
FL = Focal Length (Approx)



Angle of View | source:

Long / Telephoto (Zoomed-in) Lens:
10 | The usual Telephoto / Zoom Lens Limit. Typically angles lower than this isn't often used.
...|
18 |
19 |
20 | (FL = 105) Recommended for Close up/ Telephoto from HowStuffWorks
21 |
22 |
23 | (FL = 90) What I've been using previously
24 |
25 |
26 |
27 |
28 |
29 | (FL = 70) Beaker
30 | (FL = 67) Beaker
Normal Lens:
31 | (FL = 65) Beaker / About.com Minimum Limit for Normal Lens AOV (anything lower is a telephoto lens)
32 |
33 |
34 |
35 |
36 | (FL= 55.4) Syomya 's Maximum recommended limit
37 |
38 |
39 |
40 | (FL = 50) HowStuffWorks / dpreview.com / Loads of net sites about cameras
41 |
42 |
43 |
44 |
45 | (FL = 43.5) MS Dogs's :p approximation of the AOV of the eye
46 | (FL = 42.4 adjusted) dpreview.com's approximation of the AOV of the eye
...|
56 | About.com Maximum Limit for Normal Lens AOV
(This is pretty wide... anything higher is classified a Wide angle lens, used for large scenes, groups of people, etc.)



conclusion:

So, I guess, modeling in any AOV in the normal range is fine and if you're going to be zooming in alot to get extreme close ups of features of the face, then 10 - 30 AOV seems to be a good bet (as long as it still looks good in the normal lens AOV limits too)...

also, plz correct me if I have made any errors!

[Lunatique]

If you have it set at the highest possible, does that mean you get zero distortion? I have mine set on the highest possible right now.

[gnarlycranium]

Whoa... so.... um.... eh? I don't get it. What's the view angle of the human eye? Why do people seem to be giving it a whole range (from apparently 20 or so to 40)... does it change or something?

[ceql]

Hmm, according to most camera sites, around 50mm focal length (40 degrees AOV) is considered the most similar to the human eye.

However, at the same time, any AOV between the extremes of 31 degrees to 56 degrees, is what is produced by "normal" lenses.
When they call these lenses normal, I'm assuming that anything between those ranges will look fairly natural, and have enough perspective to them to make them look convincing (So, they aren't too fish-eye and not too orthographic looking)... and so, using anything between these extremes must be a-okay?

If anyone is a photography expert, plz fill me in! ;)




Also, my last conclusion was a bit vague...



***********************
Real Conclusion:
[EDIT: This conclusion is outdated... please Read the continuing posts!]

So, here is what I'm thinking... (I've spent all day yesterday and today thinking about this now :p)

First of all :


the higher the Angle of Vision, the more fish-eye-effect there will be when you get closer to the model. As you get further away from the model, the distortion becomes less noticiable.

The lower the Angle of Vision, the less Fish-eye-effect there will be when looking at things closely. The object won't change much in distortion whether you are close to, or far away from it...
Too low a Angle of Vision, will create an unrealistic no-perspective orthographic effect, however... so we can't turn it down too low.

Distortion:


the fish-eye perspective distiortion effect is natural, and does actually happen when you look really, really close at someone's face for instance. like, if u get so close enough to someone's face that you almost look like you're about to kiss them... and it's easier to notice if you do it with only one eye open.

40 (or 39.6) degrees is the most similar to human vision apperantly... and having played around with it, it does seems to do the natural fish-eyes at about the right proximity (however, this is hard to tell for sure).


Modeling:

- However, this fish-eye effect is a pain to model heads with, as our photo references are photographed with minimal distortion (as this distortion typically don't look too flattering :p).

(note: this all depends on how close you model... if you like to zoom right up so the head fills up the whole screen, then the fish-eye is a pain!!)

- So, in order to minimise the distortion, we should lower the Angle of View to an acceptable level...


An Angle of Vision that is low, but not too low:


- AOV level has to have enough perspective to work like a real-life model, too... it can't be too low or it'll be like working in orthographic [and then it won't look right when there's a realistic amount of perspective thrown in.]

-So, the best way, imho is it to use the *Lowest* possible AOV that is within the acceptable, "normal" range of 31-56 degrees... which is 31 degrees!


Conclusion:



So, if all my assumptions are correct... then 31 degrees is the best for modeling... There is still some distortion if you zoom in too much; but there's enough perspective in the camera for it to not look wrong when u see if with a natura eyel 40 degree AOV or higher (unlike if you were to model in orthgraphic).

It's the AOV with the lowest distortion in the "normal" lens catagory. It works with what syomka said (no higher than 36 degrees). It's a number that beaker quoted too.

In fact, 31 degrees is the limit for smallest "normal" camera AOV, so you could turn it up a few degrees... 31-36 degrees sounds good!




Anwyayz, I hope I'm not going around in circles and making wrong assumptions!
I'd love to hear what you think of my reasoning... is it logical, or am I jumping to conclusions too quickly?

Thanks!!

[ceql]

lol I just realised that this is the exact same thing Lunatique said in the other thread! (I think!) :D

Hooray!

http://www.cgtalk.com/showthread.php?postid=379103#post379103

[JDex]

I believe the main reason that you see such variant in the AOV listings on photography sites is because the manufacturing of lenses (and mirrors "all precision glass") is still an imperfect science...

Remember the hubble fiasco... they were only off by like a 100th of a human hair and the telescope was rendered useless.

I believe that 36 is correct... the closer that a camera lense is to 36 the higher the price seems to be... :)

[gnarlycranium]

Ahhhhh, I get it now! Smart stuff! I'm taking notes....

[Lunatique]

You guys have to remember something:

The camera setting in 3D apps are for when you actually work on your shots--virtual cinematography. It shouldn't have anything to do with your modelling view.

In photography, to avoid distortion when closeup, you use a telephoto lense and then zoom in. The same thing should be done in your modelling port if you want to work on your model without fisheye distortion. I don't see any harm in having your focal length set at highest possible and angle at the lowest(this is what I'm doing).

Some people are saying that having no distortion is "too orthographic." I don't see how that can be a bad thing. Having no distortion means 100% accuracy in your proportions when modelling.

When it's time to animate and render your shots, THEN you can get fancy with the camera settings and create any kind of weird/interesting/cool visual styling, but when modelling, I'd say just leave it at zero distortion.

[ceql]

thnx for ur insights!

Hey Lunatique... hmm I guess you weren't saying the same thing after all :p You have definetely have a good point though!!


Most closeup photos of faces (and thus good reference material) would have been taken from a telephoto lens... and thus not have much perspective... so modeling in more orthographical perspectives to match the photos makes sense, too.



Working in a lower Angle of View without distortion feels alot more comfortable for me... and I was happy with that for a while... however I'm a little worried...

And this was my real concern....

because, sometimes you see people's orthographic views (say, with the front orthographic view of syomka's head) that looks very different to what the front view looks like in perspective...

Compare:
http://www.cgtalk.com/attachment.php?&postid=219933
to
http://www.cgtalk.com/attachment.php?&postid=142900

Especially how in the orthographic view, from corner of the eye to the edge of the side of the head is about an eye length's distance... and in the perspective it's less than an eye's length (almost like 2/3's of an eye's length, which is approximately how it is in real life)

And so, it looks like he definetely didn't finalise the model using an orthographic view.... and often you hear people saying that heads will always look a fair bit different in the front orthographic than from a front perspective view?

It's because of these things that I've started to wonder which way to go?


There's points that support orthographic-like modeling too....

one argument that supports working in orthographic is, that eventually, if you zoom out enough, your model will begin to look orthographic (but smaller and less noticiable, or course). BUT when you see people from really, really, far away, and thus orthagraphically, you don't suddently say, "hey! they look so diffferent!" Also, the same thing with telephoto lens, people's heads don't look funny with those, at all!

Also, as Lunqtique pointed out, there's alot of options you can have with the AOV and perspective when you're making your final render... for full body shots, the camera is too far from the model to notice perspective distortion there. Plus, for closeup shots of the head, Telephoto lens ( low AOV lens, which don't have much perspective) would be used, in real life.

So, then, if working in orthographic is correct, why do so many people seemingly avoid it? and why do some orthagraphic front views look off from their perspective front views?


Also, as a sidenote... 30-31 degrees AOV lens is, afaik about a borderline between perspective and telescopic? best of both worlds maybe?



Hmm... So, now I'm kinda as confused as I was when I started out :p ahhh what to do?

- Work in normal perspective, putting up with super annoying fish-eye distortion?

- Work in "normal" perspective, at an AOV with slightyly minimized fish-eye, (some distortion will still be there though)?

-Work completely in Telephoto and thus close to orthographic?

-Work in Telephoto, but switch frequently to perspective and make sure it looks good there, too?

-Work in in Telephoto first, and switch to perspective then edit your model to accomodate?



And most of all, I hope I'm not misleading anyone by presenting possibly wrong info!! I'm honestly still confused as there's seemingly contrasting info coming from both sides of the coin (Ortho vs perps modeling). Or is it that there's no real right or wrong answer... is it just a whatever-works-for-you thing?

uhh, I dunno... my brain is broken now! mmm need sleeeeep! ;)


But anywayz, more insight is always interesting!

[Lunatique]

Well, think about this:

When you frame shots in animation, how often would you actually go up close to the point that your character's face actually distorts? Not often. The times you do it are probably in shots from psychological thrillers, comedies, action, horror films..etc, and those are very unique shots to show a certain psychological state of your character, or a unique mood.

So, if you frame your shots 90% of the time in telephoto and zoomed in for zero distortion, why should you be concerned about modelling in the same focal length/angle?

If there's a pitfall to modelling in high focal length and low angle, someone please enlighten us. I'd be curious to find out too if there are any problems. So far, I can't think of any.

[Crapstick]

This has been bugging me for ages. In theory, you'd think that'd be the way to do it - pull back and zoom in - same as portrait photographers do. But I've found that this usually doesn't suit the rest of the scene/animation and when you readjust the camera, the head can look quite different - long before you're into wide angle psycho-drama territory. Unless you widen the angle, you've got to pan and tilt a lot to get everything in and that looks very amateurish.

I generally do as Lunatique suggests, but usually have to widen the angle and go back and tweak the head.

I dunno what the solution is...maybe it's just my crappy modeling:shrug:

[ceql]

Hmmm, Ok, I'm starting to think that TelePhoto IS indeed the way to go!

Considering...
+ With perpective Cameras, Heads look orthographic if you move out enough from them enough... and if you are making torso/ full body shots [even shoulder shots] and using a normal, realistyic focal length, then you know they're going to look like how you intended
+ For closeups just use telesphoto cams like the pro's do... and since you've modeled in telephoto, it should look good too :D [edit: sentence fixed... was typing and forgot the time and had to rush out, didn't get to proof read over this part :p]


Even with a within-"normal"-range 31 AOV, there's still a fair amount of perspective distortion when you zoom right in (still very noticiable if you zoom in close enough so that the head takes up more than the whole screen height)... It's still a huge improvement over modeling in 54.4 degrees (MAYA default), anywayz :)

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

Very interestingly however... I found another site that says that 25 AOV is meant to a realistic human AOV, and that 50mm (which works out to be about 40 AOV in Maya) is just for cameras?

Also, 25 degrees is considered, in terms of cameras, in the Telephoto range if it were an AOV for a lens... There's still some perspective distortion if you zoom in, but dramatically less than the Maya fish-eye default.



when it comes to human behavior, psychologists have been debating this question for decades. With lenses, what's normal in terms of a "normal focal length" is comparatively easy to determine.

The human eye has a focal length of about 25mm and covers a horizontal area of about 25 degrees. Since we are used to seeing the world in this perspective, this 25-degree angle represents a normal perspective for film and TV cameras. However, in the latter case, "normal" depends on the focal length of the camera lens, which in turn depends on the area of the film or target. (The bigger the film or target area, the greater the normal focal length of a lens needs to be to cover that area.)

Still photographers have a good rule of thumb. With a 35mm still camera, a 50mm lens is considered normal because this is approximately the diagonal distance from one corner of the film to the other.



more info, some interestesting tidbits too: http://www.cybercollege.com/tvp011.htm




Or is it just that cameras and eyes are completely different and I'm getting myself mixed up? :p

--------


hmmmmmm I might just stick to using Telephoto 22 AOV cuz that's what I've been modeling in (I originally set 22 AOV/90 FC as a random adjustment due to being too frustrated with the default Maya fish-eye distortion).

---------


quote From Lunatique:
If there's a pitfall to modelling in high focal length and low angle, someone please enlighten us. I'd be curious to find out too if there are any problems. So far, I can't think of any.

I'm dying to find out too! if anyone comes up one, plz write in!! :D


Thanks!!

[gnarlycranium]

Ahah! I feel much enlightened now-- this will even help me with using perspective photos for reference! I wasn't sure how to adjust the angle to get the view of my model to match that of a photo-- now I know what range to try, it's a much lower angle than I was thinking. This might finally fix the distortion problem I've been having with my Hayden Christensen model-- the back of his skull would keep getting really huge when I tried to line it up to the photos, and his ear was sticking way out to one side. Ahhhhh, it is good to figure out useful things!

So far I'd been modeling at an angle of about 30-40... now I'll try 20 and see how that works.

[ceql]

Good Luck with your head :D :)

[ceql]

I have to thank every1 again for their replys, ahhhh I can model in peace now :D

[beaker]

My only issue is I want to see an object exactly as I would see it through my own eyes holding an object in front of me, not how the camera sees it or how I would see it in a photograph. Thats why I go with 65-70.

[ceql]

I think I like to zoom in too much (I maya, I move in closer than I would if I was working on a sculpture in real life) and so, I have to cut down on the distortion from all the extreme close-ups I seem to automatically keep doing :p

I guess, In the end... a properly modeled head should look good in both strong telephoto and normal perspectives :) And if not... there's always camera tweeking to cover it up :D :D

[Lunatique]

Originally posted by ceql
I have to thank every1 again for their replys, ahhhh I can model in peace now :D

I see the point in that, but I have a concern:

You models are like your actors. In real life, you don't alter people's heads/bodies with plastic surgery so they fit whatever lense you are shooting your movie with. You use camera techniques to make the people look good in your shots.

So, I tend to think along the same lines in 3D. You models are your actors, and they need to look good without any kind of angle/field--as people do in real life. Then, you make them look good with your virtual camera.

Does that make sense?

[ceql]

Yup! :)

New GamePlan for modeling: I'm going to model in telephoto, and then once that's done, I'm gonna check to see if it looks good in a normal eye-matching Angle of View... if not, I'll try and figure out why, and then go back and edit it in telephoto... rinse and repeat, until I get a model that works well in *both* real-world perspective and strong telephoto... :D :) :)

[tonygib]

Ok, well I read all this and now my head hurts :)

I know what everyone is getting at but still not sure what the bottom line is.

So, can someone give me a simple conclusion? I model in max, its default perspective viewport has a FOV of 45.

Hence, who is saying what that should be set to and why?

And then what effect will that setting have to the final rendered image if it is rendered from a "standard" 35-50mm camera (which has a FOV of 54-40).

thanks

[Lunatique]

tonygib- That's what everyone is waiting to find out. No one's given the "bottomline" answer yet.

Seasoned big studio pros? Anyone?

[tonygib]

Lunatique: ahh OK so I didn't just miss something then.

Well, in that case, how about a quick survey of sorts. Lets assume for just a very very brief moment of time that the people who make these apps know what they are doing.

Hence, max's perspective viewport has a FOV of 45 by default.

What is the same setting for Maya, XSI, Lightwave, etc, etc?

I only have max, so don't know about any of the rest.

[Matt-Clark]

Lets not forget that the brain 'corrects' the distortion from our eyes. Our brains wont correct the distortion from a camera mimicking the fov of our eyes.

[ceql]

Originally posted by Matt Clark
Lets not forget that the brain 'corrects' the distortion from our eyes. Our brains wont correct the distortion from a camera mimicking the fov of our eyes.

Whoa, That's very interesting to know... Good point! :) :)

hmm that's another blow against modeling in an eye-matching Angle Of View.... ;)

[Grugi]

I am modelling a female head right now and was asking the same question to me. Because the reference photos I use ALWAYS have at least "a bit of distortion"

So .. most of us use photos as reference, and the photographer tried to get as less distortion as he could get... but you will never have a photo that has 0 perspective distortion, which means (imo), working in a free ortho view isnt a good idea because you always get differences when you compare your model with your ref.

Trying to fit your cam´s fov to the fov of your reference pic is the way to go?!

I´m very interested how Stahlberg or other guys who modelled human heads for years handle this.


Hmmm.. I´m confused too :rolleyes:

[pauljs75]

Also there's another thing about photography that might be confusing people. Using the same lens focal length with differing film plate sizes will produce different lens angles. So using a 50mm lens on a 35mm film camera gives approximately 46-47° field of view. Using the same lens on another camera using 60mm film (I think that's what some pros use) will produce an wider field of view (I don't remember values off-hand though.)

Usually I just go with the 35mm film equiv. of a 50mm lens and set it the FOV to the 45-47° range. Or if you're wondering how strong the effect is, just bring in a flat plane with a grid texture and adjust lens angle to suit your taste. (That way any barrel effect will be readily visible.)

P.S. If you're interested in a good reference book on Photography, try the Prentice Hall/Pearson Education Photography book 7th edition (ISBN 0-13-028271-5).

Remember, ortho is generally for modeling from flat planar views of stuff such as plans and blueprints. If you're eyeballing something, it's better to stay in perspective mode.

[ceql]

Also there's another thing about photography that might be confusing people. Using the same lens focal length with differing film plate sizes will produce different lens angles. So using a 50mm lens on a 35mm film camera gives approximately 46-47° field of view. Using the same lens on another camera using 60mm film (I think that's what some pros use) will produce an wider field of view (I don't remember values off-hand though.)


Yes, you're right! That's something I've noticed since starting this thread. (hehe Which, now being a year old has run out of stream :)) Changing the Film gate presets in the Maya camera gives totally different FOV values for the same focal length!

Hmm, maybe someone should start a new thread, as all my listings of Focal Length-> FOV values are probably wrong, as I just plugged in focal length values straight into the default camera settings, oops!



One lil thing I've noticed about distortion, is that when I need a quick-fix for how the head looks front-on, I can just apply a 2x2 lattice to it, and then scale the front of the lattice. (With the pivot point in the right place :)) While this does change how the model looks from other angles, it's not overly dramatic, and it can always be retweeked. It's sort of a hacky last resort if you really need to remodel because of using a FOV you're now unhappy with :) Perpective itself seems to have a linear fall-off.


btw, Thanks very much to all who've participated in the discussion here, it's been much appreciated and please continue to post any findings/interesting notes!

[ambient-whisper]

i personally try not to be too correct in this regard. i just go for the camera output that will be used for the shot. so i might go between 40-45 in most cases.

[Psan]

Thanks, I learnt a lot from this discussion.

The most common mistake one does when modelling from a photo is to stick that photo in front ortho view and align vertices with it as closely as possible. This produces not too bad looking models. But...

When such model is seen from a perspective, you get bad results sometimes...because, your model has now a default distortion already applied in it [as you exactly matched a photo], and the perspective view adds its own distortion over it....So a dual distortion sort of.

One way I use to correct it, to scale up the model [say a head] just a bit, so that when perspective foreshortens it, it regains the proportions....but I know its a cheap trick, and I advise you do this for models you already created and dont want to tweak them now.

The eyes have a total 120 deg FOV + 180 deg FOV for peripheral vision, but most of the area remains out of focus !! except say 5 deg for fovea, when you look at a person's head say from 3 feet, you see most of his face, its better than an ortho view.....becuase the brain combines the two views.
Actually we dont see with our eyes, but with our minds...so no lens can match what we see.
The camera never tells truth :twisted: , as opposed to popular belief. People judge differently on same photo about the distances and proportions. So its all subjective.

IMO, model in ortho view and use your own judgement for tweaking it in perspectives.

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.