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Poser F.A.Q (Updated: 2016 Nov 29 4:50 pm)


 Subject: Minitut - Dramatic light and shadows for portraits - NO NOSTRIL GLOW

bagginsbill opened this issue on Feb 09, 2006 · 68 posts

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  bagginsbill    ( ) ( posted at 11:52AM Thu, 09 February 2006 · edited on 1:38PM Mon, 13 February 2006

Attached Link: http://www.renderosity.com/messages.ez?ForumID=12356&Form.ShowMessage=2573899

Over the last few days there was a discussion (see link) around getting rid of nostril glow. Since I was asked for more information on how to do it, I am posting here a mini-tutorial. Step by step I'll show you how to get really good shadows on a closeup portrait and get rid of nostril glow forever!!

I'm posting again at top level because I bet some people missed it, so this will get it noticed.

There are nine more steps, so please try to wait for the next nine posts before asking questions, which I will be delighted to answer.

This tut will focus on infinite lights. Similar techniques will be needed for spots. IBL and point lights will not be covered here.


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  bagginsbill    ( ) ( posted at 11:54AM Thu, 09 February 2006  · @2577133


Add your figure.
Select and use the face camera.
Orient the camera - I've chosen this perspective.

Tip: Check your Focal length. Too small and it distorts the figure. I like 150 mm.

Now delete all your lights.


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  bagginsbill    ( ) ( posted at 11:57AM Thu, 09 February 2006  · @2577136


Add a light.
Select the light properties.
Check the "Infinite" option.
Edit the Shadow Min Bias: set it to .1


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  bagginsbill    ( ) ( posted at 12:00PM Thu, 09 February 2006  · @2577142


Switch to the light parameters.
Set the shadow map size to 1000.
Set the xrotate to -20
yrotate to 10
zrotate to 0

You can use other orientations, but try this for now.

The light should be red,green,blue all at 1.0
Intensity 100%

Render.

Look!!! No nostril glow. But the shadows are fuzzy and indistinct. We'll fix that next.


Renderosity forum reply notifications have been wonky in the past. I'm testing the waters to see if it's working now. If you ask me something and I don't come back, it probably isn't. (Updated January 17, 2017)

  bagginsbill    ( ) ( posted at 12:04PM Thu, 09 February 2006  · @2577145


The thing poser does wierd is that it sets up the generation of shadows by using an extra camera called a "shadow cam". Before rendering your image, it pre-renders from the point of view of this camera, marking all the spots in the scene where light falls or doesn't fall. Because the camera is looking at so much more than the face, it is wasting information that isn't needed. We want it to focus on the face and neck.

So for now, right click on the camera selector in the preview window and choose the shadow cam. Don't worry about what number it is. I don't know why poser starts numbering from how many were in when you started poser. For me, there were three lights in the beginning, which I deleted. Anyways look through that camera.

Also, select the camera in the parameters window.

You should see something like my image. If your figure is not in the center of world space it may look different.

IMPORTANT: There is a wierd bug regarding shadow cams. After inserting a light, they do NOT show what they are actually looking at until you do at least one render. That's important!!! Whenever you add a light, before trying to work with the shadow cam, do a quick render. Even if you render nothing, it will "set" the camera properly.


Renderosity forum reply notifications have been wonky in the past. I'm testing the waters to see if it's working now. If you ask me something and I don't come back, it probably isn't. (Updated January 17, 2017)

  bagginsbill    ( ) ( posted at 12:08PM Thu, 09 February 2006  · @2577149


Now comes the non-intuitive magic. We need to scale down the camera!

For my picture of V3 in default pose, scale=12% works good for the head and neck.

Now as soon as you set the 12%, the camera will show a closeup of her feet. I don't know why, but the camera zoom always moves the camera to point at global coordinates 0,0,0. We need to adjust that.

For my figure, a yTran=510 works well. Sometimes you move xTran a little. Just get the portrait part of your figure completely in the image.

We want to make sure the area of interest is as big as possible, without leaving anything out. If you zoom too far and render, you will see the shadow mysteriously cut off at an arbitrary point. That means that your face camera can see something the shadow camera doesn't see. If that happens, scale up a bit and recenter the shadow cam.


Renderosity forum reply notifications have been wonky in the past. I'm testing the waters to see if it's working now. If you ask me something and I don't come back, it probably isn't. (Updated January 17, 2017)

  bagginsbill    ( ) ( posted at 12:09PM Thu, 09 February 2006  · @2577152


Now switch back to your face cam view and render.

This is what I get. Nice clean sharp shadows. No light in nostrils. Teeth get some light but have a nice shadow. Good shadow under the upper eyelid onto the eyes.


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  bagginsbill    ( ) ( posted at 12:11PM Thu, 09 February 2006  · @2577155


Let's add another light for a dramatic backlit effect.

Add your light. Set it to infinite. Set min bias as before to .1.

Set the map size to 1000.

RGB 1.0,1.0,1.0
Intensity 100%

The orientation should be close to opposite the camera. Here I set yRotate to -160.


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  bagginsbill    ( ) ( posted at 12:13PM Thu, 09 February 2006  · @2577156


Now we want to adjust the shadow cam for this light.

Remember: DO A QUICK RENDER FIRST. Otherwise you will be wasting your time.

Here I'm looking through my shadow cam lite 5 (actually the cam for light 2 - still with me??)

Adjust scale and ytran as needed. For me, the backlight worked at 13%, ytran=510.


Renderosity forum reply notifications have been wonky in the past. I'm testing the waters to see if it's working now. If you ask me something and I don't come back, it probably isn't. (Updated January 17, 2017)

  bagginsbill    ( ) ( posted at 12:14PM Thu, 09 February 2006  · @2577161


Now render. Notice the nice ear shadow. If you have a blinn node in your skin material like me, then you'll also get this nice shine on the side of the head and neck.

This concludes the tutorial.

I DON'T WANT TO SEE NOSTRIL GLOW IN THE GALLERY AGAIN, OKAY!!!!?!?!?


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  KarenJ    ( ) ( posted at 12:39PM Thu, 09 February 2006  · @2577186

Great stuff, thanks for posting. What kind of render time did you experience with the above shot?


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  spedler    ( ) ( posted at 12:40PM Thu, 09 February 2006  · @2577188

Great tutorial, thank you. One question: what are the pros and cons of using your technique with depth-mapped shadows vs. ray-traced shadows? I've tried your test set-up with both and seem to get better results with eyelashes using ray tracing, although the shadows on the eye itself and the teeth seem better with the depth-mapped version.

Steve

  bagginsbill    ( ) ( posted at 12:43PM Thu, 09 February 2006  · @2577189

1 minute


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  bagginsbill    ( ) ( posted at 12:54PM Thu, 09 February 2006  · @2577199


Spedler - there are situations where the raytraced shadows may work better, but I rarely find it to be so. This image, which could probably be fixed by tweaking parameters, shows an improvement of detail on the eyelash shadow, but does a bad job on the eyelid crease and the teeth. Plus, this render took almost 5 minutes.

The neat thing about depth mapped shadows is that you can calculate them once and just reuse. So my workflow is much improved by them. Position my character, props, and lights. I turn on the "Reuse Shadow Maps" option in the render menu. Once created, the shadow maps get reused in subsequent renders so it saves a lot of time. I can then change materials, light strengths and colors, and camera position, without having to recalculate the shadows. If I'm using the raytraced shadows, I experience the extra calculation time associated with the shadows on every test render. Of course, you could turn them off, but if you are trying to get the lighting/mat/camera angle just right, it slows you down.

So given the somewhat bad results and the increased times, I choose depth-mapped 99% of the time.


Renderosity forum reply notifications have been wonky in the past. I'm testing the waters to see if it's working now. If you ask me something and I don't come back, it probably isn't. (Updated January 17, 2017)

  Bobasaur    ( ) ( posted at 1:04PM Thu, 09 February 2006  · @2577213

Does the "Reuse Shadow Maps" option work when rendering an Animation? If the subject is moving then the shadow would change as well.

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  bagginsbill    ( ) ( posted at 1:08PM Thu, 09 February 2006  · @2577215

Correct - you can't reuse shadow maps for animations. I don't animate so I'm unclear on whether it even pays attention to that option. It shouldn't. By definition, animated figures will require a new shadow map each frame.


Renderosity forum reply notifications have been wonky in the past. I'm testing the waters to see if it's working now. If you ask me something and I don't come back, it probably isn't. (Updated January 17, 2017)

  spedler    ( ) ( posted at 1:53PM Thu, 09 February 2006  · @2577256

Thanks, that's useful.

Steve

  operaguy    ( ) ( posted at 2:12PM Thu, 09 February 2006  · @2577270

when animating poser automatically re-renders the shadow map, even if you have "reuse" selected.


  3dvice    ( ) ( posted at 2:27PM Thu, 09 February 2006  · @2577290

Thx, great tutorial, very helpful!

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  spedler    ( ) ( posted at 2:45PM Thu, 09 February 2006  · @2577309

Just a minor point, which is obvious really, but if you alter the light position you will have to realign the shadow cam. For example, changing the light's xRotate to -30 instead of -20 throws the shadow cam right off, and the radioactive nostrils come back. This can be fixed by re-adjusting the shadow cam position.

Steve

  operaguy    ( ) ( posted at 3:01PM Thu, 09 February 2006  · @2577327

for an animation, you'd have to animate the shadowcam. I find that with sufficient bias and map size, under depth map shadows, the nostril glow simply is not a factor; it is taken care of by the tight settings. However, I DO zoom in on the shadowcam for other reasons. ::::: Opera :::::


  odf    ( ) ( posted at 3:04PM Thu, 09 February 2006  · @2577337

Thanks! This is very usefull information.

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  mathman    ( ) ( posted at 3:41PM Thu, 09 February 2006  · @2577389

Thanks for the tute, bagginsbill.


  svdl    ( ) ( posted at 6:03PM Thu, 09 February 2006  · @2577521

Clear, concise and very informative minitutorial. Thanks!

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  visualgirl    ( ) ( posted at 7:13PM Thu, 09 February 2006  · @2577588

Thanks for the tip!


  Indoda    ( ) ( posted at 7:07AM Fri, 10 February 2006  · @2578186

Thank you for another great mini tutorial. Very useful.

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  semidieu    ( ) ( posted at 12:27PM Fri, 10 February 2006  · @2578474

Great ! Thank you !


  mathman    ( ) ( posted at 5:21PM Fri, 10 February 2006  · @2578797

bagginsbill, I was going well with this tutorial until step #6 of this thread, where you scale the shadow cam down to 12% and then move it up to the subject's head. When I tried this with the y-tran value suggested, the subject completely disappeared off the radar - of course she was still there, but the shadow cam had gone off in a different direction I guess. I've got two theories about this : (1) the positioning of the light associated with the cam; or (2) the units of measurement that I was using e.g. maybe I am not using Poser Units ??? Also, looked in the trusty Poser Reference Guide for some further enlightenment about the Shadow Min Bias, and the only description is as follows : "The Shadow Min Bias parameter specifies how far to shift samples towards the light source to prevent self-shadowing of objects." What on earth does that mean ? .... are you able to put this in more plain English ? thanks, Andrew


  operaguy    ( ) ( posted at 7:51PM Fri, 10 February 2006  · @2578940

working with the shadowcams is difficult. There used to be, and sometimes still is, a dial "zoom" that appears. For the life of me, I can not figure out how to make that zoom dial appear, yet once in a while it does! This is a deep mystery. Meanwhile, if it does NOT appear, you have to manipulate the thing with only the x and y axes, plus "scale". It is no fun. About the bias, LOL, I'd love an actual explanation as well. All I know is, the lower the better. I use it, but I don't understand it. ::::: Opera :::::


  face_off    ( ) ( posted at 4:22PM Sun, 12 February 2006 · edited on 4:23PM Sun, 12 February 2006 · @2581076

Attached Link: http://physicalc-software.com/forum/viewtopic.php?t=20

Good tut Baggins.

Not sure if you were aware of this, but spots lights have a much lower less shadow map size requirement than infinites. For removing nostril glow, it's much easier to do if you use spots (you don't need to fiddle the shadow cams). Details above. Also, I totally agree with you - for production renders, depth mapped shadows are better than ray-traced.

Message edited on: 02/12/2006 16:23

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  operaguy    ( ) ( posted at 6:02PM Sun, 12 February 2006  · @2581173

Spotlight fan here echoing the sentiment. I would comment, however, that fiddling with the shadowcams has its own benefits: the closer in you zoom with the shadowcam, the smaller your shadow map can be and still attain similar quality results. This, in turn, leads to faster render times because the map is smaller. ::::: Opera :::::


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