Author Topic: CGI Lighting Research  (Read 9411 times)

0 Members and 1 Guest are viewing this topic.

Offline tomi

  • Hero Dronie #2
  • ********
  • Posts: 668
  • Karma: +37/-26
CGI Lighting Research
« on: August 11, 2008, 03:08:24 am »
I began research with lighting engineers at two companies; Autodesk-3DS Max and Newtek-Lightwave.  They produce leading software available for CGI work used by the reseachers. 

My letter had to be benign of any possible legal, hence very mundane describing everyone  8)
Kris, thank you for your encouragement in this research and suggestions when this began.  Cheers :)

Here is the letter I sent to both companies.  After the 17th of August I will have a chance to communicate with Newtec engineers:

begin -

Thank you for taking the time regarding this issue.  I and a couple of other people, have been researching, as a serious hobby, an event that occured outside in daylight, afternoon sun and was captured in several photographs by one camera. 
There is a small group of people on an internet forum that takes an interest in this matter we are researching.  A few of them are computer graphic artists and they have created CGI studies of these photographs with your product and several other CGI programs available.   Their work has been commendable and would make your company proud. 
We are not sure if the EXIF data is accurate about time, but studies show that it is showing approximately the correct time according to cgi re-created studies of the objects based on the shadows in one of the original photographs.  However, there is still a dispute within the group of cgi artists about the exact angle of the sun.
More to the point of this letter, is a debate arising where some CGI artists are claiming shadow inconsistencies between the two objects in the photographs, at a very small detail level, within a relatively slight variance of the suns actual position.  This would indicate that the picture is actually a composite of the two objects, with sun angle not identical on both objects.  Other CGI artists are not so sure how viable this variance is because it is dependent on the exact replication in CGI of the objects positions relative to the camera as well as other possible factors. 
Because of this ensuing debate, it is important to assess the viability of using these CGI programs in such a forensic manner. 
Please allow me a little bit of your time to discus this matter further in order to gain some insight into the limits of use regarding the finer factors of recreating precisely the ambient conditions and effects of an outdoor environment in a photograph.
Yours truly,

Offline tomi

  • Hero Dronie #2
  • ********
  • Posts: 668
  • Karma: +37/-26
Re: CGI Lighting Research
« Reply #1 on: August 11, 2008, 03:12:29 am »
Earlier in the week I received a reply from my contact at Autodesk:

I have passed this information on the Max team so that they can comment and/or contact you. If they pass any responses to me I will forward to you as much as I can. I should forewarn you that because this is â??a serious hobbyâ? and you are not a customer of Autodesk I do not expect the developers will contact you directly, I cannot say for sure as itâ??s their decision to make but I suspect they will not.

That being said you do have other channels if you wish to pursue this further. You can visit the link below to obtain consulting information from the developers, while waiting for the final response/answer from the Max team.

As well you can visit the Autodesk forums that are free to all users, to discuss this with other Max users

On a side note, one of our Max techs was able to find a â??relatedâ? customer service request that did ask about the validity of lighting effects done it Max. Though not a direct answer to your question I thought you might find it interesting.
<<3ds max uses approximations for representing light, geometry, color, etc,  which although may appear similar or identical to real world conditions, cannot be guaranteed to be identical. Autodesk cannot support claims that an animation or image created using 3ds max is visually accurate even if the data was extrapolated from real world records. 842122>>>

As I mentioned, I have passed this to the Max Application Engineers so they can decide the best course of action.


Offline tomi

  • Hero Dronie #2
  • ********
  • Posts: 668
  • Karma: +37/-26
Re: CGI Lighting Research
« Reply #2 on: August 11, 2008, 03:15:37 am »
Continuing the dialog, on Friday I received this email from them:

Here is a bit more information from the Application Engineers

In that case, we use an equation close to radiance to position the sun in space based on location and time.  However, slight variations may occur compared to real world under some conditions. We dontâ?? claim that for example, the shadow of an object will be _exactly_ as it may be in reality. 

BTW, our sun angle calculation is exposed in the sdk so someone can spend a lot of time looking at it, debating its accuracy etc... 



  • Guest
Re: CGI Lighting Research
« Reply #3 on: August 11, 2008, 03:21:50 am »
HUGE round of applause for you!!!!!! Great work there, glad to see software like this is in actuality flawed when it comes to reproducing real world lighting and shadows.

Offline spinnewise

  • Founding Dronie
  • *****
  • Posts: 121
  • Karma: +19/-0
Re: CGI Lighting Research
« Reply #4 on: August 12, 2008, 09:16:57 pm »
Thank you, tomi!
A real experts opinion on the validity of CGI experiments versus realworld lighting.
Clear words in foggy times.
Still looking for gorillas

Offline Nemo492

  • Administrator
  • Hero Dronie #2
  • **********
  • Posts: 769
  • Karma: +30/-1
    • Ovnis-USA
Re: CGI Lighting Research
« Reply #5 on: August 12, 2008, 09:29:06 pm »
Isn't strange that the pro-fake CGI people
do not seem to read THIS section of our board ?
The only motivation for the DRT is finding the truth.