Author Topic: Chad pictures  (Read 43984 times)

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Offline spf33

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Re: Chad pictures
« Reply #30 on: June 05, 2008, 08:29:34 pm »
Do you mean, with respect to shadows and sun angles?  Or are you talking about visual perspectives?

i'm guess i'm just talking about the visual perspectives in stephen's photos and chad's (so far) scannedimage.jpg.  haven't looked at sun angles in chad's scannedimage.jpg yet.

why the heck would a hoaxer even think to tilt the drone away from the camera
like we are seeing in the stephen's and chad's photos? 

not to mention that the needed 3d tilt from stephen's photos and chad's scannedimage.jpg seems to appear to be horizontally aligned to whatever the ground plane the drones are above.

if i were faking these images, i think i would try to keep the drone level at all times. if a hoaxer decided then to tilt the drone as seen for whatever reason, it seems to me that they would have had to some serious calculations using many of the methods in this thread.

Offline onthefence

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Re: Chad pictures
« Reply #31 on: June 06, 2008, 04:47:04 pm »

majicbar

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Re: Chad pictures
« Reply #32 on: June 07, 2008, 03:51:10 am »
I see a power pole to the right side of the picture, a nexus on power poles?

Offline nekitamo

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Re: Chad pictures
« Reply #33 on: June 07, 2008, 05:22:54 am »

i didn't even check the dimensions of the drone torus in the 3d until right now...4.2 meters.


Interesting... 4.2 meters is exactly what I got. Does this mean we've both reached the same results by using two different methods of analysis? That would be great, 'cause I was kind of waiting for your verification before continuing to analyze other images.

Offline spf33

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Re: Chad pictures
« Reply #34 on: June 07, 2008, 06:58:50 am »
the same results by using two different methods of analysis?  ...verification before continuing to analyze other images.

i should probably spend a couple\few more hours in the file and get the dem in there and readjust the scene assets to make sure that that the terrain doesn't somehow throw the alignments off.

but just looking in ge i can't see too much of a change in the 3d...i was going to jump onto scannedimage5 to check out the size correlations, i'll tighten up the scannedimage 3d scene first then.



Offline nekitamo

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Re: Chad pictures
« Reply #35 on: June 07, 2008, 01:49:42 pm »
Well, here's all I could think of to do about scannedimage5 (or #2 per elevenaugust's notation)... a simple distance calculation using EXIF data and previous size assessment:


Offline spf33

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Re: Chad pictures
« Reply #36 on: June 09, 2008, 04:33:32 pm »
elevenaugust\10538,

i'm having a bit of troubling getting this to resolve.

the areas circled in green are causing issues when trying to rectify the scene with elevation data.

the drt\pi photos seem to indicate that the ground plane area in front of the large foreground tree on the right in scannedimage5 is quite lower than the photographers ground plane position.

yet, in google earth and using the usgs dem data, the terrain there only differs by
10'-15' in elevation from the area in front of the tree to the photographers position.

you can see the 3ds max camera view and how the circled area seems to be mostly flat from the camera to the tree, but in the drt\pi photos the terrain seems to drop quite a bit.

having been there, can you describe that area a bit?

i'd like to resolve this before i say much more about any of the other chad photos, but scannedimage.jpg is resolving pretty good in the same scene, although i think now that the drones tilt position is not horizontally aligned to the ground plane below it.

scannedimage5, is resolving to show the drone around 300' from the camera.
but i need to continue to refine the scene to get a better handle on lens and fov, so this could change.


 
« Last Edit: June 29, 2008, 06:21:40 pm by Nemo492 »

Offline 10538

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Re: Chad pictures
« Reply #37 on: June 09, 2008, 07:44:46 pm »
elevenaugust\10538,

i'm having a bit of troubling getting this to resolve.

the areas circled in green are causing issues when trying to rectify the scene with elevation data.

the drt\pi photos seem to indicate that the ground plane area in front of the large foreground tree on the right in scannedimage5 is quite lower than the photographers ground plane position.

yet, in google earth and using the usgs dem data, the terrain there only differs by
10'-15' in elevation from the area in front of the tree to the photographers position.

you can see the 3ds max camera view and how the circled area seems to be mostly flat from the camera to the tree, but in the drt\pi photos the terrain seems to drop quite a bit.

having been there, can you describe that area a bit?

i'd like to resolve this before i say much more about any of the other chad photos, but scannedimage.jpg is resolving pretty good in the same scene, although i think now that the drones tilt position is not horizontally aligned to the ground plane below it.

scannedimage5, is resolving to show the drone around 300' from the camera.
but i need to continue to refine the scene to get a better handle on lens and fov, so this could change.
 

Hi Spf,

Yes there is quite a step down from the camera location.  I would estimate the difference at about 20 feet.  I have a picture taken from below the #1 position which does show about a 20 foot rise.  I believe the spot is equal in elevation to your green spot.  11Aug correct me if I'm wrong.

Offline spf33

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Re: Chad pictures
« Reply #38 on: June 09, 2008, 08:44:22 pm »
I would estimate the difference at about 20 feet.

ok, that's disappointing.  unless i totally screwed something up, the elevation model is clearly inaccurate and combined with all the other unknown variables in chad's case i feel like i might be standing on shaky ground(!) with this 3d study.
 
does that area look like it could have been excavated or anything like in the past decade? 

i'm currently emailing with a gentleman from the usgs so more info forthcoming...



Offline 10538

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Re: Chad pictures
« Reply #39 on: June 10, 2008, 04:54:14 am »
It is very possible the area was excavated and leveled.  There is a road there.  I'm sure some work was done to get it level.  I don't know when the road was put in however.  I can ask if needed.  But is the difference between 10-15 feet and 20 feet that big of a deal?  If you like I might be able to get a more precise measurement of the difference in elevation between the two because I'm basically guessing with the 20 feet.  It could be 15 I guess.  I'm trying to remember if there is a 5 foot rise between the other photo location and the spot you have indicated.  That's a tough one.

This picture shows the change in elevation between the two:
http://droneteam.com/images/IMG_0931.JPG
The shrub on the left is about two or three feet tall.

« Last Edit: June 10, 2008, 05:24:26 am by 10538 »

majicbar

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Re: Chad pictures
« Reply #40 on: June 10, 2008, 05:19:35 am »
Could a dozen readings on GPS elevation be averaged for both locations and then determine the relative elevaitons, or is DRT's GPS not that precise? Surveyors have GPS that would answer this if more precision is needed to deterrmine the answer.

Offline 10538

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Re: Chad pictures
« Reply #41 on: June 10, 2008, 05:40:45 am »
Could a dozen readings on GPS elevation be averaged for both locations and then determine the relative elevaitons, or is DRT's GPS not that precise? Surveyors have GPS that would answer this if more precision is needed to deterrmine the answer.

Unfortunately, we did not have a gps with us.  We had everything else but one of those.  Doh!

majicbar

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Re: Chad pictures
« Reply #42 on: June 10, 2008, 05:53:39 am »
Is there EXIF data for Chad's photos? I'm curious about the time of day and the effect that sun angle is playing on the shadow cast on the tree.

Offline tomi

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Re: Chad pictures
« Reply #43 on: June 10, 2008, 11:44:35 am »
I have a surveyor friend who lives in Calif and he would be able to help I'm sure.  If there are any questions to know about that he could help with, let me know please.

Offline spf33

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Re: Chad pictures
« Reply #44 on: June 10, 2008, 03:37:23 pm »
I have a surveyor friend who lives in Calif and he would be able to help I'm sure.  If there are any questions to know about that he could help with, let me know please.

thanks, tomi.

i think i've figured out the issue i'm having with chad's scannedimage5.
the resolution of the elevation data i'm using is 10m.  the free data i'm using doesn't quite have the resolution i need to resolve scannedimage5 100%.

perhaps the surveyor has access to higher resolution elevation data?

update on my emails with the usgs;

"Just to let you know, the NED is a compilation of the 24k DEM data sets.  The NED also has been updated in some areas across the country with higher resolution elevation data but I am not sure about your area of interest.  To completely answer your original questions, I will have to wait until Thursday to pass this onto the person who usually answers the SDTS questions.  Do you need an answer before then?

I hope you find our data helpful and useful.  Let us know if you have additional questions. "