Digital humans the art of the digital double
Ever wanted to know how digital doubles are created in the movie industry? This course will give you an insight into how it's done.
# 1 05-02-2003 , 07:03 AM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135

HDRI

Well, I'll go make a very simple model in the next hours and I have decided that I want to use mental ray to illuminate the scene with a hdri image. And use a HDRI for reflections.

I have no idea if this works for me, but I want to try. I'm figuring that the results will be top notch. user added image

Stay tuned.

# 2 05-02-2003 , 08:28 AM
kbrown's Avatar
Moderator
Join Date: Sep 2002
Location: London, UK
Posts: 3,198
There are some hdri images at www.debevec.org if you want to take a look.


Kari
- My Website
- My IMDB

Do a lot, Fail a lot and Learn a lot!
# 3 05-02-2003 , 09:35 AM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135

Step 1

Yup user added image been there.
Actually there are few free HDR images around, it seems.

But I'll use the ones I found on one of those sites.

The model is done. It is a 100% nurbs pen.

Here's the wireframe.

# 4 05-02-2003 , 03:05 PM
ragecgi's Avatar
Registered User
Join Date: Sep 2002
Location: Minnesota, USA
Posts: 3,709
Can't wait!

Can you post your results including settings, and rendertime?

Cool, thanks!


Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com
# 5 05-02-2003 , 03:53 PM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135

Preliminary pictures

First Picture:
Maya raytrace renderer; Bumpmap is here, "going outwards". One dir-light which has a 1.5 deg light angle for smooth shadow-border. And three spotlights with diffuse and specular only, without shadow-casting.

Second Picture;
Mental ray; with no enabled lights. There are lights which are hidden, but that's just to get rid of the default lights. The light source is a surrounding nurbs-surface with hdri map as incandescence. The bumpmap is here "going inwards".

Default Production mode
With 10 000 Final Gather rays
Minrad = 0 (auto)
Maxrad = 0 (auto)

Min/Max Sampling = 2 and 2

Rendering time = around two hours with PIII, 600 Mhz, 384 MB SDRAM

Third picture; A mental ray, raytrace. It looks a little different than the "maya render", but I admit to having altering it. This rendering is not "optimal in any major way", its just a simple mental ray rendering.


Last edited by undseth; 05-02-2003 at 08:28 PM.
# 6 05-02-2003 , 04:06 PM
brian_ellebracht's Avatar
Registered User
Join Date: Oct 2002
Location: St. louis Mo
Posts: 1,580
looks nice!! Gotta love color Bleeding. user added image user added image user added image
Brian


Please check
My (old) website!
# 7 05-02-2003 , 05:35 PM
ragecgi's Avatar
Registered User
Join Date: Sep 2002
Location: Minnesota, USA
Posts: 3,709
NICE!

Keep it going! hehe! I love it!

Thanks for the info!

Can't wait for more.....


Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com
# 8 05-02-2003 , 05:42 PM
sdch1000's Avatar
Subscriber
Join Date: Jun 2002
Location: Miami, FL. USA
Posts: 110
Looking great undseth. Not to sound like an idiot but what is a hdri image? I know nothing about this.


Steven C.
# 9 05-02-2003 , 05:55 PM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135
Well, it is an image which has a higer dynamic range of color values (i think), in contrast to other formats which has only 0-255 steps (I think). Any manipulation with HDR images will keep some or all of the HDRI's "contrast value", as the image gets lighter or darker. I think it has something to do with floating points, but I know nothing about it yet user added image

oh, and the HDR image in my experiments, doesnt seem to be really neccessary after all I think. But I guess it is theoretically "better/more accurate", than a tif or a jpeg image to illuminate the scene.


I do not support Bush! Nor Saddam! Long live UN!
# 10 05-02-2003 , 06:29 PM
sdch1000's Avatar
Subscriber
Join Date: Jun 2002
Location: Miami, FL. USA
Posts: 110
Thanks, I think I have an idea. I'll do some more research.


Steven C.
# 11 05-02-2003 , 06:56 PM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135

Some results of Final Gathering

yup, based on these I'll render out a final, with an directional light.
And I might as well add an "ordinary/non FG or GI" mental ray raytrace rendering.

# 12 05-02-2003 , 08:29 PM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135

aargh

Having trouble updating pictures, here is the missing pic.

# 13 05-02-2003 , 11:46 PM
ragecgi's Avatar
Registered User
Join Date: Sep 2002
Location: Minnesota, USA
Posts: 3,709
Have to say that I still think MR FG is the best out of the three you have there, but I wish there was a way to get MR to render faster......


Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com
# 14 07-02-2003 , 02:02 PM
undseth's Avatar
Subscriber
Join Date: Aug 2002
Posts: 1,135

Final post

Well, I got to try and use a true HDR image to light my scene, and it was easier than I had though.

I wondered for some time as to how, I could lower the HDRI's brightness, and although I'm not sure this is the way to do it, I simply lowered the "color gain" in the attribute editor for the image node (the materials incandescence attribute)

I tried making the hdri file darker with the freeware HDRShop, but the tools there seemed only to produce low dynamic images like jpeg, tiff and the like.

So the "color gain" was the only attribute that gave me any results. Please correct me if I'm wrong here, or If there is any other way to darken you hdr image, to lower the light in your scene.

I am satisfied with the final rendering, but although I previously stated that this rendering would be done on the basis of my earlier tests, I did not follow up, and unneccesarily set the minmax value too low, causing the rendering time to drag out to over 18 hours. I guess the rendering time could have been shortened by skipping the directional light in my scene (with special shadow attributes (1.5 deg light angle and 15 shadow rays for smooth shadow-borders)

Next time I have to figure out how to combine FG and GI.

# 15 19-02-2003 , 03:00 AM
astroboii's Avatar
Registered User
Join Date: Feb 2003
Location: Perth, Australia
Posts: 7
So HDRI is a type of lighting for Maya like global illumination ?

Posting Rules Forum Rules
You may not post new threads | You may not post replies | You may not post attachments | You may not edit your posts | BB code is On | Smilies are On | [IMG] code is On | HTML code is Off

Similar Threads