Author Topic: A missing shadow ?  (Read 54057 times)

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Offline HPO

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Re: A missing shadow ?
« Reply #15 on: August 14, 2008, 09:33:52 pm »
To some extend I agree with you, you would need a very very fast computer to calculate everything what is out there in nature, the pure chaos out there with all it's reflections etc.
And it is always been my opinion that a human being can spot chaos over calculated things, specialy things we have been seeing since human kind exist, like predators and other human beings, I have not seen one convinsing CG human or lion yet.

But there are things in CG that can't go wrong in my opinion, one of them are cast shadows from the brightest light source, when they are going wrong in a scene the program must have bend them, cast shadows are really a straight forward calculation. Ambient light is totally different story.

Offline tomi

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Re: A missing shadow ?
« Reply #16 on: August 15, 2008, 12:04:05 pm »
My responses so far from Autodesk said the same thing. 

 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... 

And I will continue to get more insight as well.

Offline tomi

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Re: A missing shadow ?
« Reply #17 on: August 15, 2008, 12:22:33 pm »
Although I don't have the depth of knowledge that some have here when it comes to science, I just wanted to point something out that correlates to how deep this issue of light, shadows and the what are the drones might have to be considered.

Last night nemo posted an article about nonlocal entanglement.  It bothered me because the headline was misleading.  What bothered me more was reading the comments ppl wrote underneath the article.

Paired photons don't "communicate", this hasn't been a considered factor in nonlocality for a very long time.  Experiments like this been done many times previously and this phenomenon is well known already.  Nobody understands how they are connected over vast distances, that is the point. 

Nobody understand quantum theory.  Richard Feynman makes that abundantly clear, although he has been dead for these many years, it is still the same problem.  How does nonlocality work?  This as well as other factors such as the wave pattern of light, has suggested to physicists that we live in a multi-dimensional universe of which we are able to understand or perceive only 3 of those dimensions:
http://en.wikipedia.org/wiki/Branes
« Last Edit: August 15, 2008, 12:29:51 pm by tomi »

Offline elevenaugust

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Re: A missing shadow ?
« Reply #18 on: August 31, 2008, 06:32:09 pm »
Reading again the whole "California Drones" board on OMF, I noticed something very interesting in the thread created on April 2008 by onthefence.
It's about a discuss that took place between onthefence and spf in this thread.

Please everyone take a second look at this and see if what Sean said is consistent with the alleged "missing shadow" found by 1111 and Cie.

Extract:
"so i don't think i am ready to declare both incorrect exif data and a tilted main arm.

but what i am noticing is that if i move the time forward almost 2 hours to about an 8 degree sun angle the drone by itself only needs to be slightly angled to catch the sun angle near parallel while still keeping all the pole shadows correct.

still need to test the drone shadows at this angle though, so no graphic yet.

anyone have a clue how much daylight is in the sky at around 7:30pm around the end of may?

Capitola, Santa Cruz County, California (longitude W122.0, latitude N37.0):
Wednesday 16 May 2007 Pacific Daylight Time
Sunset 8:10 p.m.
End civil twilight 8:39 p.m.
"


Original thread here

Edit to add: We also must be aware that the large fin on the Chad photo is not on the same plane as the craft:


Moreover onthefence Is HPO aware of the work you've done on your real cardboard model? It could be a good idea to show him.
The lightning of both the pole and the drone are consistent with those of Raj's picture.

So, is it possible that Raj's camera date/hour was improperly set and that the hour could be most likely 7:30PM?? Could the pole shadows be correct at this hour?
« Last Edit: December 01, 2008, 10:21:06 pm by onthefence »
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Offline Nemo492

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Re: A missing shadow ?
« Reply #19 on: August 31, 2008, 06:36:24 pm »
I always had a difficult time to figure that
the family was "having dinner" so early in the afternoon,
like 5:50 pm..
http://ovnis-usa.com
The only motivation for the DRT is finding the truth.

Offline onthefence

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Re: A missing shadow ?
« Reply #20 on: August 31, 2008, 06:42:00 pm »
I always had a difficult time to figure that
the family was "having dinner" so early in the afternoon,
like 5:50 pm..

Just some opinions:
  • It does seem early, many gatherings of people in North America usually eat supper at 7PM.
  • I always had the impression that the accepted standard time in a house is 6PM.
  • My wife and I have often visited restaurants as early as 4:30PM to avoid the long line-ups.

Offline elevenaugust

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Re: A missing shadow ?
« Reply #21 on: August 31, 2008, 06:44:09 pm »
I always had a difficult time to figure that
the family was "having dinner" so early in the afternoon,
like 5:50 pm..
Oh, yes; I forgot this and I agree too. :D

Do you think onthefence that you can make matching the shadows of your cardboard model with those of Raj16 with a later hour?
« Last Edit: December 01, 2008, 10:19:11 pm by onthefence »
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Offline onthefence

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Re: A missing shadow ?
« Reply #22 on: August 31, 2008, 06:59:52 pm »
Do you think onthefence that you can make matching the shadows of your cardboard model with those of Raj16 with a later hour?

None of my model was based on time-of-day, I simply tried to match the shadow shown in the photo. All shadow anomalies on the Raj drone craft where explained to my satisfaction with my cardboard model. I did not do the work to get the pole shadows matched as that effort requires much more work and many variables.

To answer your question, no, I don't think I can do that since I cannot assume that the drone was laying horizontal to the Earth's surface, and I cannot assume that the pole is perfectly vertical against the Earth's surface. Someone will have to play with all those variables separately.

I believe that HPO has seen my work on that subject already. It proved that one small fin must have been angled off the plane of the other small fins.

Maybe HPO wants to make a 3D pole model as well ;)
« Last Edit: December 01, 2008, 10:19:32 pm by onthefence »

Offline HPO

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Re: A missing shadow ?
« Reply #23 on: August 31, 2008, 09:54:12 pm »

I believe that HPO has seen my work on that subject already. It proved that one small fin must have been angled off the plane of the other small fins.

Maybe HPO wants to make a 3D pole model as well ;)


Yes I have seen your work on that subject, the angle of that arm can easaly be adjusted on the model. The angle of the main arm is  difficult to adjust.

By making a 3D pole model you mean a real physical object I presume  ;), I have to look into that, a lot of parts from the pole can be made of real wood of course.
I don't nesseseraly have to use expensive Objet parts for that, but I can use some advice for measurements for that telephone pole in relation to my drone model.
The outer diameter of the main ring on my drone model is 15 cm for comparison, so about 1:30 scale.

Offline onthefence

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Re: A missing shadow ?
« Reply #24 on: August 31, 2008, 10:07:20 pm »
The angle of the main arm is  difficult to adjust.
That is too bad, because the Chad photos appear to show a definite difference in plane of at least a few degrees.



Quote
By making a 3D pole model you mean a real physical object I presume  ;), I have to look into that, a lot of parts from the pole can be made of real wood of course.
I don't nesseseraly have to use expensive Objet parts for that, but I can use some advice for measurements for that telephone pole in relation to my drone model.
The outer diameter of the main ring on my drone model is 15 cm for comparison, so about 1:30 scale.

Wood would be fine.

While I did my experiment, I found it pretty easy to move one object around in my hands to get the shadows correct. Combining the pole into the scene might require another person, or more patience. You could try it all outside, but the moving Sun might be too frustrating to work with. I saw that you had a manipulator vice/arm in one photo, that should come in quite handy for experimenting with both pole and craft using a fixed indoor spot light source.

Offline HPO

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Re: A missing shadow ?
« Reply #25 on: August 31, 2008, 10:29:09 pm »
That is too bad, because the Chad photos appear to show a definite difference in plane of at least a few degrees.

Well it was my plan to give the metal rods in the main arm some pre "force" or pre "bend" upwards to compensate for it's downwards bending it has now because of it's own weight, I could give it some more to have a more upwards angle.

While I did my experiment, I found it pretty easy to move one object around in my hands to get the shadows correct. Combining the pole into the scene might require another person, or more patience. You could try it all outside, but the moving Sun might be too frustrating to work with. I saw that you had a manipulator vice/arm in one photo, that should come in quite handy for experimenting with both pole and craft using a fixed indoor spot light source.

Yes I also think that would be more easy to do, I can adjust what ever I want in a long time span, but I will be missing a lot of ambient light this way.

(edit): this is a link I found some time ago, but it doesn't mension the total lenght of a typical pole, I can of course total the 10 and 15 feet but I don't think that's accurate.

http://ops.fhwa.dot.gov/publications/telecomm_handbook/chapter8.htm
« Last Edit: August 31, 2008, 11:05:44 pm by HPO »

Offline 10538

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Re: A missing shadow ?
« Reply #26 on: September 01, 2008, 07:20:01 pm »
So, is it possible that Raj's camera date/hour was improperly set and that the hour could be most likely 7:30PM?? Could the pole shadows be correct at this hour?

Yes it is possible the date was not set correctly.  I think the most likely discrepancy would be forgetting to reset for daylight savings time which had initiated two months earlier.
That would have made the actual time 6:42PM.  I can't see a likely way the actual time was 7:30PM though.

Offline HPO

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Re: A missing shadow ?
« Reply #27 on: October 20, 2008, 10:34:50 pm »
Hi,....at first I didn't know if I would post the first test picture, because it is far from perfect.
I had to do this indoors because it was already late.
Immediately I noticed the difference between the sun and this point light, it will not give the same shadows, but maybe it gives a good indication.

The second problem is the scale of the telephone pole, when I want to put the camera close to the pole it gets all blurry because of the pole being to close to the lens, BTW I used an older Sony camera for this shot because it has a tilting lens, so I can look at the display or viewfinder without laying on the ground.

I have to try a lot of different set-ups, but the first test is hopeful, although I couldn't really get the angles exactly right. One of the problems that still exist is the dark spot on the item15, when I move the light so that there is a shadow from the main arm casting on the item15 other shadows are getting out of place, and other parts get highlighted that don't get highlighted in the original.
One thing I already noticed, this is going to take a lot of time, the combinations of tilting and moving the objects seems endless.

The first test pictures, first the photo and second the set-up (don't mind the messy place LOL it's the workshop not the office  ;D )
 


« Last Edit: October 20, 2008, 11:24:59 pm by HPO »

Offline onthefence

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Re: A missing shadow ?
« Reply #28 on: October 20, 2008, 11:19:04 pm »
Thank you for your persistence!!

One thing I already noticed, this is going to take a lot of time, the combinations of tilting and moving the object seems endless.

No kidding! I hope we're all still alive when you have finally exhausted the last possibility :)

I hope you won't have to resize the pole too many times either ;)

Keep up the good work ...
One of your fans.
« Last Edit: December 01, 2008, 10:19:47 pm by onthefence »

Offline HPO

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Re: A missing shadow ?
« Reply #29 on: October 20, 2008, 11:45:22 pm »
Thank you for your persistence!!

One thing I already noticed, this is going to take a lot of time, the combinations of tilting and moving the objects seems endless.

No kidding! I hope we're all still alive when you have finally exhausted the last possibility :)

I hope you won't have to resize the pole too many times either ;)


Keep up the good work ...
One of your fans.

LOL,...yeah I hope I'm alive too after it.

About the resizing of the pole, when the raj drone is about the same size as the Chad drone, this pole has to be about the length it currently has.
Getting the focal length correct without a blurry pole will be the biggest problem I think.
« Last Edit: December 01, 2008, 10:20:12 pm by onthefence »