# Topology research

#981

The problem is the focal length. When you look at the image using the orthographic views, in this case the front view, the focal length is infinite. This doesn’t exist in reality because it would mean a scene where the perspective lines never converge. Imagine a pair of train tracks. If they are seen in a orthographic view, the tracks would never converge.
The shorter the focal length, the faster the tracks come to a point in the distance.
That is why when using a macro lens, everything looks distorted and objects in the distance seem way smaller and farther away than the foreground objects. If you use a telephoto lens, like the ones photographers use at sporting events, the objects in the distance look a lot larger than in real life and closer as compared to objects in the foreground.

If we apply this knowledge to your image, it’s easy to see part of the problem you are having. (The other part has to do with anatomical issues, but I won’t deal with that here.)

When you look at your work through the perspective view, the ears which are farther back seem to get smaller and the seem to disappear behind the zygomatic arches. The sides of the head converge to rapidly as if looking through a fish-eye lens. On the other hand, the nose feels enlarged because the heightened perspective makes it disproportionately bigger as it comes closer to the lens. The shorter you make the focal length, the larger the nose will be in relation and the smaller the ears will be.

When you look at your image through an orthographic view, There is no perspective (this doesn’t exist in reality), the focal length is infinite. So as a result, the ears aren’t affected by perspective and as a result they look larger than they would appear in real life. The nose is affected by feeling smaller than it would in real life. You can test this by opening the image in a program like maya and sliding the focal length of the camera back and forth while maintaining the image at screen size. This is what Alfred Hitchcock used to do to create a scary uncertainty in some of his shots. They called it a Hitchcock Zoom. He would zoom out while dollying the camera in and closer to the figure. This would create that crazy horror movie effect where the person’s face remains the same size while the room seems to get larger as all the background elements seem to get smaller. Check out the movie “Vertigo” to see this effect in full bloom!

The human eye has a focal length that is somewhere between 50 and 75. A professional portrait photographer, who is worth his salt, will use this knowledge to make the people in his portraits look better. Many will use a telephoto lens in the studio and place the camera farther away in order to do close ups. This makes the people look beautiful because it makes the nose look smaller than in real life. Usually any focal length above the human eye’s focal length will generally cast the close-up of the human face in a favorable light.

Because you are using reference that has perspective, while working in a view that has no perspective, You are not getting accurate results. Since there is no foreshortening on the ears and nose in your mesh, you are fooled into thinking that the ears are smaller than they are. But in actuality you are making the ears too small. The reverse is true of the nose and it results in the nose being too big on your mesh. Thus the distortion that you are getting. The perspective view of you model is a more accurate representation of what your mesh looks like in reality.

In order to work around this problem you need to do one of two things. First of all, you must not work in orthopedic views. You should lock your cameras in perspective views. Do this for all your views, front, back, side, top, and all the 3quarter views. If you are working from image planes, you must do your best to match the focal length used in the reference shot. This provides most accuracy. If you aren’t working from image planes, you should set your camera focal length to somewhere between 50 and 75. Even if you are not using reference, it’s a rare occasion where it is better to work on a portrait while looking through orthographic views. Imo, I suggest you don’t do it at all when working with heads.

The best 3d portraitists, usually only use image planes set up on and looking through perspective views. This is usually for the blocking in stage and to double check proportions. They mainly use the image plane (in locked perspective views) to capture the primary forms of the head. Then they open up as many reference pics of the model that their monitor will allow and eyeball it from there as if they were working from life. This way of working allows for the most accuracy.

I suggest you take your reference shot and attach it to a locked perspective camera in front, side, and 3quarter views. Then get the main shapes that way. And if you are going to resolve the portrait from the image plane reference, then at least stop using the orthographic view to work from, at least when you are doing faces.

(Btw, the lack of a decent perspective camera and the lack of a focal length setting in earlier versions of z-brush is partly why the skymatter guys created mudbox when they were at WETA.

Personally, it used to drive me crazy when I would send a z-brush v2 sculpt in for 3D printing and the result would look nothing like what I saw on my screen. This problem was cleared with mudbox and in z-brush 3 and above.)

Good luck, and I hope that helps and I hope that I am clear. I apologize to the rest of the community for rambling on. I always mean to write one sentence and then it turns into a novel

Btw, here is a link that talks about the Dolly Shot
http://en.wikipedia.org/wiki/Dolly_zoom

#982

wow that’s a lot to take in, but not to worry, I was able to understand it, and I learned a lot out of that. Thank you anyway I do hope my anatomy is better on this one now. I did what you said about setting up camera’s for the front and side and there was a big difference from the ortho views:

After looking at several female head models, I have to make the head rounder and bigger above the eye. One of my references for anatomy:

#983

@razeversious
I’m glad you understood what I was saying.
I’m hesitant to post anatomy crits on this thread because this is more of a technical thread. But you should post the head on one of the anatomy threads on this forum. There are some seriously knowledgeable people in this community.

In any case, just one word of advice, I think you should hone your anatomy skills from reality instead of other people’s models. Use photos to work from when you are practicing and and look at other great artists to see how they apply reality and how they solve the different problems involving the translation from reality to a piece of art.
In other words if you want to learn how to sculpt a nose, look and copy real noses, but look at the old masters and the modern masters to see how they do it.

#984

thanks mookiemu unfortunately I’ve posted in the wrong forum then at the wip or 3d stills. I don’t wanna make a new post somewhere else since it’ll look like I’m trolling :shrug:

I’ve retopologized her face to something similar to the ones i see here :). Thanks for the advice, will do further research

#985

Hi,

I just put up the first of twenty or so Articulation videos on Vimeo. These will be part of a new section on my web page. This section will cover Articulating the face but I have not launch the web Part yet.

This is just a sample that tries to explain the way that I go about working on the design of a character mesh. It’s all done on the wipe board and on the web it will be explained in greater detail, with more example of this type of mesh.

All these video will be more on the art side and not the technical rigging part.

Cheers,

HD

#986

Mookiemu! That was a great explanation about focal length!
I knew the effect you explained from my experience trying to make heads. So I was wondering wow to work around it, for I used a lot to put my references on ortho views and do a lot of the work there. I had came up with the possible solution of making photos of heads from a very far distance and a very closed FOV so I would get a less perspective-distorted picture that would suit best my orthos… I thought it was genial.
…until I read your advice:

And then it was like: :banghead:. I must say yours is a lot better idea. I will try it out right away!
Anyway, maybe some one would like to sometime use my long-focal-length-reference idea, as you are able to pan the ortho view and yet being able to work model on top of your reference picture, what cannot be achieved if using perspective views… (and what might be not really necessary most of the times, I admit)…

#987

Hmm! Interesting, I’ll try your long focal length idea. I like it, it’s always interesting to hear how other artists solve common problems

What I’ve been doing lately is to note the focal length that I’m shooting at and then use the same focal length in Maya. I’ve been trying to shoot at mostly 50 for more realism and at 75 for more idealism since it makes the nose look smaller and generally makes the models look more attractive. I try to stay within those parameters since 50-75 is supposed to be the basic focal range of the human eye. When I use other people’s reference I’ve been trying to guess what the focal length is and trying to match it.

I don’t know, I may be getting too anal about this but it does seem to net better, more accurate results. In any case, I’ve been mostly doing this for the blocking in stage and for speed checking proportions. Once I have the primary forms blocked in, I like to work more by eye with photo reference scattered all around my monitors than by image planes. Even so, I still like to have the perspective camera match the focal distance of my reference, even if I’m not working from photo reference.

#988

Yo, guys, check my topo here.
It is intended for the face of a very cartoonish girl with non-realistic shaders I plan to use for my next short film. Eyelids are not there yet, but I feel good with the rest of the topo.
When you look at the ears (and some other parts), please mind that she is a female cartoon with very simple shapes.
Coments and critics, please, please!

:buttrock:

#989

where is it?

#990

Sorry, I had forgotten to attach it. Ive edited the post, so there it is now.

#991

still nothing

#992

I do not know what could be happening. I can see it right now on the original post.

Anyway,here is the link again…

Sorry so much for the inconveniences.:sad:

#993

Hi,

my web site for face and videos is dwn for the time being.

HD

#994

very nice! except for that n-gon where the top of the ear connects to the face. But if you aren’t gonna take this into zbrush or mudbox, I don’t think that would be a problem.

I love the way you handled the wings of the nose.

#995

Looking forward to seeing it

#996

Thanks! I do not plan to take this to ZB or MB… I can’t work with neither of them. Besides, this is going to be a very simple shaped character. I think I am not going to tweak the face geometry much further than it is right now, except for the eyes…
About the NGon… I decided to leave it there (and not run a new loop from there all the way to the eye ) after watching some wires from Steven Stahlberg that sometimes feature these kind of loops ending abruptly at a NGon (5gon)… so I thought: Hey, the smoothed version of this looks fine to me, and that part of the face will almost not be deforming in animation, so I think I can go with this.
That I thought after reviewing closely this thread:
http://forums.cgsociety.org/showthread.php?f=7&t=108412&page=1&pp=15
where Steven post and talk about such wires.
I have always been told to look out for NGons… but what about if it is located somewhere where the mesh will not deform?
This is just my opinion, and I am not 100% sure about that. Would love to read your opinion and some other’s about that.

(By the way, thanks again. Your words are a great inspiration for me:beer:)

#997

I totally agree with you on that. And Steven is a modern master.

I really think that if the area is not going to deform, and the software can handle the n-gon, why not? Especially since you aren’t taking this mesh into zbrush or mudbox, both of which complain when they come across an n-gon.
I also thought it would be unnecessary to continue add more geometry by extending the loop all the way to the eye.

But I’d be interested in what some of the other guys on this thread think too.

Good luck on your project.

#998

Keep in mind that the post from Steven you link to is about 8 years old. His workflows and ideas have never been set in stone, previously he’s been using the Maya hierarchical subdivision surface implementation, and NURBS before that. I he’s using Zbrush (and why wouldn’t he) I’m willing to bet he’s working with all quads and maybe a few triangles, too.

Then again if you don’t plan to use zbrush, don’t want to animate your model and so on then it’s of no consequence if you use n-gons or too few polygons. But in that case I don’t know why you care about topology at all… If I were to make a still image I wouldn’t even bother that much with modeling, just sculpt in zbrush and export a high res mesh (maybe decimate it a little if it’s too many polygons)

#999

I think he plans to animate it, just not in the ear area.

Even if you do only stills I think it’s still beneficial to have some concerns about topology because it makes posing and tweaking the poses easier, and good topology can considerably lower the weight of your mesh. But that’s changing too as you pointed out. The Decimation master works incredible well.

I agree, with you completely on what you said about Steven. That post was a long time ago and he was doing mostly stills I believe. And he wasn’t using any sculpting tools back then.

#1000

Oh, I do plan to animate this model, and I want to perform facial expressions, but those deformations will not include the area where the 5gon is. But on the other hand will be deforming the whole head, not for facial expressions, but to achieve a squash-and-stretch effect that is so common in traditional animation. But I think this kind of deformation will be ok with the 5gon since it will be more like non-uniformly scaling the head, so the 5gon and the surrounding mesh will only vary on proportions.

And yes… I first noticed that the first post from Steven was years ago, and although it looked pretty fine to me even today, I was never really sure it was a completely correct way. That is why I asked on this thread. To listen what people like Mookiemu and Laa-Yosh (an many more dudes, I hope) had to say about that idea. If I had thought I was completely right, I would not even bother to post.

And, shame on me, I do not know anything about Z-brush or Mudbox. Even in Max, I correct the shapes of my meshes using transform tools (move, rotate, scale). So, when I have to “sculpt” a model like this, I go moving all the verts, which is a very tedious task, but I feel I have more control over the shape than if I use the paint deform tools…