Author Topic: A missing shadow ?  (Read 54060 times)

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Offline onthefence

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Re: A missing shadow ?
« Reply #30 on: October 21, 2008, 12:00:34 am »
Getting the focal length correct without a blurry pole will be the biggest problem I think.

That might be difficult unless you get the exact same camera as Raj used and the pole and drone are exactly the same and distance as what Raj saw.

Maybe a pinhole camera or one with a small lens would have a longer focus length.

Offline 10538

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Re: A missing shadow ?
« Reply #31 on: October 21, 2008, 05:51:03 pm »
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.

It's probably safe to assume the Raj drone is the same size as the Chad drone.  Remember that Nekitamo and SPF33 both determined the Chad drone to be about 18 meters in length.  Lev made this comparison.


It will be very hard to find the exact combination of variables to accurately duplicate the Raj pict16.  This is the reason imo that many naysayers give up and conveniently proclaim it's impossible.

Can it be done with models?   Can the sun be accurately substituted by a lamp?


Offline HPO

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Re: A missing shadow ?
« Reply #32 on: October 21, 2008, 07:29:05 pm »

Can it be done with models?   Can the sun be accurately substituted by a lamp?


I did a quick test today with the macro setting on the camera on the pole, the pole looked ok this way, so maybe that's the way to do it with models.
I haven't had the time today to test it with the drone yet.

But No,...the lamp can not be an accurate substitute, it can not recreate the parallel light rays of the sun, not even when I place the lamp a long distance away from the set-up.
And of course the light intensity gets to small this way.

« Last Edit: December 04, 2008, 06:45:37 pm by 10538 »

Offline HPO

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Re: A missing shadow ?
« Reply #33 on: October 23, 2008, 07:55:37 pm »
Hi Numbers,

To be honest, I will be surprised if you two find a way to match all the shadows, I couldn't in 3D software.

I made some pictures of the pole in different times of the day to compare the shadows.
It was during working time but the sun was shining at those times of the day in between some rain showers, so I had to do it quickly and without positioning the drone above, that would have taken to long and my Boss wouldn't be very happy.

The first one at 12.45pm and the second at 4.45pm, I adjusted the position of the pole to keep the shadow of the upper crossbar in the same position.
As you can see the shadow of the lower crossbar almost doesn't seem to move but the top shadow shrinks in size.
The shadow in Pict16 is relatively large for the time of the day at that date IMO.
 


« Last Edit: December 04, 2008, 06:47:16 pm by 10538 »

Offline 10538

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Re: A missing shadow ?
« Reply #34 on: October 24, 2008, 12:25:16 am »
For the late afternoon pic, try rotating the pole and camera (with respect to the sun) counter-clockwise (as you look up).  This should put that upper shadow from more toward the outer portion of the crossbar.  Also your camera position appears to be too close to the pole.
« Last Edit: October 24, 2008, 12:26:44 am by 10538 »

Offline HPO

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Re: A missing shadow ?
« Reply #35 on: October 24, 2008, 07:32:42 am »
I'm not exactly shore what you mean with
Quote
This should put that upper shadow from more toward the outer portion of the crossbar
, I was referring to the length of the shadow downwards on the pole.
You are right when you say the camera is to close to the pole, it's hard to look at the display of the camera in this position,... but the shadow doesn't change when you move the camera.

Offline onthefence

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Re: A missing shadow ?
« Reply #36 on: October 24, 2008, 12:01:17 pm »
Explaining graphics with text is going to be painful.
Suggestion for 10538 or others: use graphical examples to help HPO understand requests.

Edit to add: I think this is what 10538 was trying to say, but I'm not sure about the direction of rotation.

  • The Sun is in a fixed position in the sky, so it is impossible to move the light source to accommodate shadow changes.
  • Red arrows show direction that the pole needs changing. The camera must follow the pole rotation so that the picture framing looks the same.
  • The green circled areas show the current mismatch in shadows



HPO, I'm sorry if this seems too demanding, but I think 10538 is trying to save some pain when the picture is presented abroad and criticized by the drone haters.

Obviously, tiny changes like these will end up being impossible using the Sun, as it's position is changing throughout the day while you are struggling for perfection. I suggest just using the spotlight as you did before in your factory unless you can somehow set up a jig to hold the drone and pole outdoors.

Good luck!

PS. This is a private forum, so I made my photobucket albums private so that others cannot browse freely.

« Last Edit: October 24, 2008, 01:21:34 pm by onthefence »

Offline 10538

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Re: A missing shadow ?
« Reply #37 on: October 24, 2008, 05:44:06 pm »
I'm not exactly shore what you mean with

I'll try to illustrate.




Offline HPO

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Re: A missing shadow ?
« Reply #38 on: October 24, 2008, 06:56:53 pm »
I'm not exactly shore what you mean with

I'll try to illustrate.





Oh, but I did do that of course, I turned the pole to get the longest shadow, and this was it, that was the point I was trying to make.

Offline HPO

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Re: A missing shadow ?
« Reply #39 on: October 24, 2008, 08:12:15 pm »

HPO, I'm sorry if this seems too demanding, but I think 10538 is trying to save some pain when the picture is presented abroad and criticized by the drone haters.

Obviously, tiny changes like these will end up being impossible using the Sun, as it's position is changing throughout the day while you are struggling for perfection. I suggest just using the spotlight as you did before in your factory unless you can somehow set up a jig to hold the drone and pole outdoors.

Good luck!



Thanks onthefence, I will certainly do some more tests in the factory, but the best will be the real sun of course with it's parallel rays. 
I'm still thinking about a set-up that is easy and quick to install outside, but it's getting wintertime and the weather is getting worse. 

Offline nekitamo

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Re: A missing shadow ?
« Reply #40 on: October 25, 2008, 09:27:50 pm »
The first one at 12.45pm and the second at 4.45pm, I adjusted the position of the pole to keep the shadow of the upper crossbar in the same position.

Hmm... your second image reminds me of one of my early experiments with 3d shadow analysis when I considered only the small, dark spot on the top of the pole to be the actual crossbar shadow (image links to my OMF post):



Later, I dismissed this and joined the "mainstream" opinion, but what is interesting about this angle is that it results in best possible match between drone and pole shadows. If pict0016 is indeed a composite image, maybe its author made the same (wrong?) conclusion about the crossbar shadow?

Or should this angle be (re)considered more carefully? It is strange why this little patch is so much darker than the rest of the shadow below.

Offline HPO

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Re: A missing shadow ?
« Reply #41 on: October 25, 2008, 09:51:21 pm »
Yes,..that darker spot is interesting, my thought was/is that it is a shadow of one of the insulators on top, I have to test that theory, the Objet machine is actually building the scale insulators this night.


Offline spf33

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Re: A missing shadow ?
« Reply #42 on: October 27, 2008, 04:09:39 pm »
not quite sure what my opinion on this is yet:



but again, thanks for all your hard work and efforts hpo!


Offline 10538

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Re: A missing shadow ?
« Reply #43 on: October 27, 2008, 08:04:13 pm »
It's good to see you again, SPF.   8)

Offline spf33

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Re: A missing shadow ?
« Reply #44 on: October 27, 2008, 10:02:19 pm »
It's good to see you again, SPF.   8)

hi numbers, thanks.  i'm here every day even if not posting.  ;)

some observations;

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?

debated 3d software technological capabilities aside, the 3d study done on pic14 seems to indicate and correlate with pic16&17 exif time stamp data of around 5:4x pm: 



and



i find it really hard to believe the exif data is incorrect when several 3d studies from various people show extreme correlations.

on the other hand, this is comparing mine, kris' and hpo's study of pic16 all show matches using slightly different horizontal angles on the drone;



It's hard to believe that soemone who have the skills to reproduce perfect chromatic aberrations can make a huge mistake like the main arm shadow missing.....

this line of thought is something i continually come back to also.

hpo, can we get a side-view of this setup?  it's kind of hard see the exact angle your light is hitting the drone at;



numbers, is it possible for hpo to borrow the minolta? 

and then have hpo take some real world photos at his location when the sun is at a comparable alt and azimuth to the raj photos?

or vice versa - getting hpo's model to numbers or someone near capitola to make test shots around may 2009?

« Last Edit: October 27, 2008, 10:07:15 pm by spf33 »