Author Topic: Chad pics  (Read 30692 times)

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Offline Arkhangels

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Re: Chad pics
« Reply #30 on: July 02, 2008, 01:37:34 am »
Hi everyone!
Here is my part:
Obs: 70º is not the sun angle, but the angle of the shadow in that inclinated surface, in that particular image...



I didnt put a sun angle in that image because this image was just to help you guys, not solve things up :)
Regards
Ark

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Offline spf33

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Re: Chad pics
« Reply #31 on: July 02, 2008, 01:51:43 am »
ok.  once again i'm an idiot.
forgot to hit the daylight savings check box.
in 3ds max the altitude is 56° at 3pm and 45° at 4pm on may 1 2007.
at 6pm the alt\az is 21°\272.
so that will shift all the hours in the previous animations.

with daylight savings time:



« Last Edit: July 02, 2008, 02:28:02 am by spf33 »

majicbar

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Re: Chad pics
« Reply #32 on: July 02, 2008, 06:15:22 am »
Given your latest appraisal of angles and times I would say the time would be closest to 4:30 PM. Guesstimating about 35 degree sun elevation at about 260 azimuth. I think most of the shadows in Chad's photograph pretty much agree with what you have posted. This is a really great way to explore this photograph: the complexity only grows.

Offline spf33

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Re: Chad pics
« Reply #33 on: July 02, 2008, 04:05:06 pm »


possible the shadow is being cast onto trees that are in front of the laser range finder measured ones?



update:

« Last Edit: July 02, 2008, 05:52:35 pm by spf33 »

Offline 10538

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Re: Chad pics
« Reply #34 on: July 02, 2008, 06:36:08 pm »
Good analysis, Spf.  Your sun angle and azimuth looks accurate.

The circled green question mark on the left is the big one.  Exactly how far is the shadow from the camera?

How did you determine the drone location?  Nekitamo determined the drone to be at least 130 feet from the camera, I believe.


Offline spf33

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Re: Chad pics
« Reply #35 on: July 02, 2008, 07:27:28 pm »
How did you determine the drone location?  Nekitamo determined the drone to be at least 130 feet from the camera, I believe.

once the camera matching is setup - sensor size, lens, and field of view - it's a simple matter of taking the 3d drone mesh with it's estimated and generally accepted width of 13.5' and positioning it (closer\larger or further away\smaller from the camera) so that it matches the size in chad's scannedimage2.jpg.

limitations?  if the estimated size of the drone is incorrect then that will put the drone further or closer depending on if it's larger or smaller than 13.5'.  so for example, if the drone  is actually 27' wide then that will put it roughly twice as far away from the camera.

the drone in the max screengrabs is sitting at about 105' from the camera vs nekitamos estimation of 130'.  not sure yet how high the margin of error would be in the 3d scene, don't think it would be as high as 25'.  so not sure what could be causing the discrepancy.  both of us using different sensor\lens\fov estimates most likely.

although comparing to nekitamo's last post on scan2 here, both ours are looking fairly close.

Offline nekitamo

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Re: Chad pics
« Reply #36 on: July 02, 2008, 07:29:50 pm »
How did you determine the drone location?  Nekitamo determined the drone to be at least 130 feet from the camera, I believe.

I believe he matched the distance and orientation of the drone until it looked exactly like in Chad's image, and inset image above his render shows excellent match indeed. This should be way better then my angular size method.

But I'm not sure about camera position, it seems way behind the tree and almost exactly below the drone in pic #4. I think it should be more to the southeast. Also, measurements were done from yet another, third spot, a bit more to the northeast (check 15m marks in #5, one is obviously more distant than the other).

Too bad your video was removed, as it shows that stretch of the path and relationship between images #4 and #5 in great detail.

EDIT: just saw spf33's answer in the meantime... the discrepancy is probably due to my imprecise matching of Chad's image into your shot, I'll try to repeat the process. We both used the same size for the drone, that shouldn't be the problem.
« Last Edit: July 02, 2008, 07:35:07 pm by nekitamo »

Offline 10538

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Re: Chad pics
« Reply #37 on: July 02, 2008, 08:00:53 pm »


BTW Spf,  what does the inset that has the red circle with the arrow pointing into it indicate?

Offline spf33

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Re: Chad pics
« Reply #38 on: July 02, 2008, 08:13:22 pm »
the red circle with the arrow pointing into it indicate?

it's a crop of this image from 11a, used because that was the last image posted showing scan2 laser measurement position.

i actually wondered if i should have obscured it as to not cause any confusion before i posted...
« Last Edit: July 02, 2008, 08:15:18 pm by spf33 »

Offline nekitamo

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Re: Chad pics
« Reply #39 on: July 02, 2008, 10:03:33 pm »
Here's a comparison between two proposed distances. Perhaps background image was shot too far from original Chad's location for proper alignment of all objects? If so, it is more important to match sizes then positions of objects - and the tree at 85m mark seems like good fit with spf33's solution (32m).



Btw, I'm talking about distance from camera to arrow marked position on the outside of the drone ring, not the tip of its tail which is almost 10m closer, or the center of the ring which is some 2m more distant.

Offline spf33

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Re: Chad pics
« Reply #40 on: July 03, 2008, 06:06:08 pm »
it is more important to match sizes then positions of objects

updated a bit and had to move the drone closer a bit than my quick
105' estimate.  seems the best fit for a 13.5' wide torus right now puts the drone at 88'11";



Offline 10538

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Re: Chad pics
« Reply #41 on: July 04, 2008, 12:29:41 am »
My only question is if it's not a shadow from the small arm then what is it?  It is shaped just like the arm.  Definately looks artificial.  In my mind it is laying exactly as one would expect it to lay.  I know you guys are finding the drone is closer and can't be casting a shadow on a bush that is 50 meters away.  Could it be the bush (at the area of the shadow) is actually closer?

If the arm sticks out another 8 meters from the 40 meter mark, that might put the shadow over the bush if let's say the spot on the bush is only 40 meters away.


Offline Arkhangels

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Re: Chad pics
« Reply #42 on: July 04, 2008, 01:42:12 am »
Uhmm I think that shadow be from the drone is highly improbable....

For that shadow to be there, if the sun is in the "back" of the main ring and the bush, the drone itself would have to be behind the bush (more to the southwest), and it would look a lot smaller in the pics right?



Regards
Ark
« Last Edit: July 04, 2008, 01:43:51 am by Arkhangels »

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Offline spf33

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Re: Chad pics
« Reply #43 on: July 04, 2008, 03:23:20 am »
My only question is if it's not a shadow from the small arm then what is it?  It is shaped just like the arm.  Definately looks artificial.  In my mind it is laying exactly as one would expect it to lay.

agree;


Quote
I know you guys are finding the drone is closer...

i feel that more tests are needed.
now that hpo has offered up a chad drone solidworks model let me get that in the scene.
and experiment with some alternate camera sensor size\lens\fov ans see what happens.

are you guys positive of the location  the measurements were taken?

Quote
Could it be the bush (at the area of the shadow) is actually closer?

could this be a possibility?


Uhmm I think that shadow be from the drone is highly improbable....

this is not me supposing where the shadows and sun are. 
it's the 3ds max daylight system:

"The Sunlight and Daylight systems use light in a system that follows the geographically correct angle and movement of the sun over the earth at a given location. You can choose location, date, time, and compass orientation. You can also animate the date and time. This system is suitable for shadow studies of proposed and existing structures. In addition, you can animate Latitude, Longitude, North Direction, and Orbital Scale."


Quote
For that shadow to be there, if the sun is in the "back" of the main ring and the bush, the drone itself would have to be behind the bush (more to the southwest), and it would look a lot smaller in the pics right?

i'm not sure i follow you.  the lighting and shadowing seem fine to me:

7am-7pm




« Last Edit: July 04, 2008, 03:25:58 am by spf33 »

Offline elevenaugust

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Re: Chad pics
« Reply #44 on: July 04, 2008, 06:41:49 am »

could this be a possibility?


Yes, Spf, could be that these trees are closer than expected. However, 20-30m distances differences between the two trees lines seems to me a little over-estimated.
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