# Drone Research Team

## Drones Research Team - Research => Photo analysis => : elevenaugust May 24, 2008, 04:06:21 AM

: elevenaugust May 24, 2008, 04:06:21 AM
Here, we (10538 and I) will post all the pictures and the infos needed for the calculations, regarding the Chad location.
: Re: Chad pictures
: Nemo492 May 24, 2008, 02:43:59 PM
example :

: Chad location 2
: Nemo492 May 24, 2008, 03:17:43 PM
: Chad location 4
: Nemo492 May 24, 2008, 03:22:01 PM
: Re: Chad pictures
: elevenaugust May 24, 2008, 07:39:30 PM
I will try today to take measurements for each photos with the laser range.
I will also upload all the photos in the ftp sever, maybe easier for you.

My first impression about the size of Chad's drone, looking to the pictures 4 and 5, is that this thing is really big!!
: Re: Chad pictures
: elevenaugust May 25, 2008, 01:38:02 AM
(http://img79.imageshack.us/img79/7945/laserrangen2vt4.jpg)

All measurements are on meters
: Re: Chad pictures
: elevenaugust May 25, 2008, 01:49:14 AM
: Re: Chad pictures
: elevenaugust May 25, 2008, 01:52:48 AM
: Re: Chad pictures
: nekitamo May 25, 2008, 10:51:31 PM
My first impression about the size of Chad's drone, looking to the pictures 4 and 5, is that this thing is really big!!

This thing really seems enormous! I've noticed that two of your distance measurements in image #4 are almost exactly in-line with one of the drone's central axis and the drone seems to be very near the canopy, so I did some quick (and rough) calculations just to get overall impression of its size. I aligned Chad's image with one of yours (IMG_0943) and by using Field-of-View angle info from image's exif data I extrapolated the dimensions of two overlapping (due to the perspective) square image planes, actually separated by 14 meters vertex per your measurements. Then I calculated the size of the diagonal line from point A to B (22m in 3D space) and used it to judge the size of the central ring (perspective foreshortening ignored) - and here's the result:

Again, this is a very rough estimate - but 4 meters?! Are those trees really that big?
Must be something wrong with FoV angles... does this seem right to you?
: Re: Chad pictures
: elevenaugust May 26, 2008, 04:48:33 PM
Hi Neki, just landing off the plane  :P and read all your great calculations.
Kudos for that!
I just want to add that, yes, that was my first impression when we made, Numbers and I, the distance estimation with the laser range, that this thing was:
1. VERY close to the canopy
2. VERY big

However, two things to consider:
1. When we went to the spot firstly, we wrongly interpreted Chad's position and placed it close to point nÂ°5, and when we returned here, we both agree to place it further, to match the little branches on the left side and the general aspect of the vegetation on the right side, therefore it could be more useful and more accurate to use the photos
DSCF011
DSCF012 and
DSCF013
(http://droneteam.com/images/dscf0011su3.jpg)
(http://droneteam.com/images/dscf0012fb1.jpg)
(http://droneteam.com/images/dscf0013bc4.jpg)

2. I wonder if Chad used the zoom.... And how it can affect the calculations?
: Re: Chad pictures
: nekitamo May 28, 2008, 10:43:52 AM
I've been checking and refining my calculations for the past few days and I'm going to repeat the previous example explaining every step of the way, but this time trying to be more accurate and using one of the new images (http://droneteam.com/images/dscf0013bc4.jpg) suggested by elevenaugust. It would be great if someone tries to follow and verify my reasoning here, as I believe this method to be quite useful as an universal tool for "manual" 3D image analysis.

Here are the basic ingredients:
- unknown image for analysis, with unknown parameters, but shot at known location
- calibrated image from the same location, as similar as possible to the previous one
- physical measurements from the location (laser measured distances)

The calibrated image is simply an image with known parameters from which we can deduce the precise angle of view. For this we can either use EXIF metadata (if present) or calculate it by using an object of known size and at known distance in the image. As final precision of this calculations depends mainly on precision of this image, it should be as good as possible (high resolution, undistorted, high contrast, low noise...), though it doesn't have to be perfect if its flaws are known and corrigible - i.e. if it was shot with the angle-of-view-calibrated camera with known barrel distortion (this calibration can also be done later). Here's one of the suggested calibration images with basic info and illustration of the angle of view concept:

(http://img207.imageshack.us/img207/4740/image1qe3.jpg)

It was resized to 50% of its original size which reduces precision (btw, can I get hold of the original image?), though unlike clipping it doesn't affect the angle of view. As EXIF data survived, I extracted it with Phil Harvey's EXIFtool (http://www.sno.phy.queensu.ca/~phil/exiftool/) which automatically calculates horizontal FoV (48.9Â°) if the required input data fields (focal length and 35mm scaling factor) are present. The other way to do it would be to ask elevenaugust how far from the camera he was standing and what is the format of images he's holding. Assuming it was plain A4 paper (0.3m longer size), by measuring it in PS or similar program with a ruler tool (75px) we can deduce the pixel size for the image distance plane (another important concept here) containing the paper (75/0.3=250px/m), and also the width of the whole image (Xres=800px) at the specified distance plane, so 800/250=3.2m. This seems about right, if you can imagine elevenaugust's full height and rotate him horizontally to measure the width of the image. If we enter this value along with the previously determined HFoV (48.9Â°) into the on-line angular size calculator (http://www.1728.com/angsize.htm), it returns the distance of 3.5m from the camera.

The next step is to overlay the image with an unknown object (Chad's image #4 per elevenaugust's numbering notation) onto the known setup of our calibration image and align it by using reference points present in both images in order to translate objects dimensions into known and measurable environment - this is the basic postulate on which my calculations depend, and if it's not correct I'm sorry for wasting your time. But as I believe that was also the reason why you tried to match the original images, we are probably safe in using this assumption :)

As you can see in the following image, I used rotation, perspective correction, resizing and whatever else was necessary to achieve as good alignment as possible:

(http://img149.imageshack.us/img149/5020/image2rd5.jpg)

I believe this also answers elevenaugust's question about zooming - as long as unknown image can be precisely aligned with the calibrated one, it doesn't matter what parameters were used for its recording because by translation into our known setup we are effectively replacing its parameters with known values. Naturally, it would be better if calibration image already matches the unknown without adjustments, but that is not the case with either of images from the location. Even if they were perfectly aligned from the exactly same spot, there's wind, vegetation growth, etc...

But here's another thing, specific for this case: the alignment of images is not even necessary! It will serve as an illustration, but for actual measurement I will use the original image with a line drawn between two selected reference points (marked A and B) identified in both images. I've entered  laser distance measurements for these reference points and marked the square that I'm going to use in the next part of my calculations, especially selected because, as you can see, its imaginary diagonal line is passing very close to craft's horizontal axis along the smaller side fins, and it looks as if the craft is very close to the tree canopy - so, hopefully, by calculating the size of this diagonal line we could use it to measure the actual dimensions of the craft.

To be continued...
: Re: Chad pictures
: elevenaugust May 28, 2008, 11:24:04 AM
Hi Neki,

Amazing work! :)
1- These photos were taken from 10538's camera, I'll ask him to post the original here without resizing
2- Yes, the paper I was holding is an A4 format
3- You're absolutly right about my distance from the camera, 3.5 meters is a very good estimation.
: Re: Chad pictures
: spf33 May 28, 2008, 01:37:53 PM
really nice work, nekitamo.
while i haven't done 3d studies with the chad image\location yet, right now in 3ds max i can corroborate the estimated FOV of ~48Âº(max calculates 48.217Âº), so you are definitely on the right track.

: Re: Chad pictures
: 10538 May 28, 2008, 03:46:47 PM
Hi Neki,

Amazing work! :)
1- These photos were taken from 10538's camera, I'll ask him to post the original here without resizing
2- Yes, the paper I was holding is an A4 format
3- You're absolutly right about my distance from the camera, 3.5 meters is a very good estimation.

Here it is:   http://home.comcast.net/~dl1027/files/object/08052313.JPG (http://home.comcast.net/~dl1027/files/object/08052313.JPG)
: Re: Chad pictures
: nekitamo May 29, 2008, 03:36:46 PM
Here it is:   http://home.comcast.net/~dl1027/files/object/08052313.JPG (http://home.comcast.net/~dl1027/files/object/08052313.JPG)

Thanks, I will use this one for my further calculations. I assume that laser measurements were also done from that exact same spot? This is also an important detail I've neglected to emphasize in my previous post, but I can compensate for offset if you can provide the details.

while i haven't done 3d studies with the chad image\location yet, right now in 3ds max i can corroborate the estimated FOV of ~48Âº(max calculates 48.217Âº), so you are definitely on the right track.

Well, I've just spent hours trying to figure out the right way to precisely calculate FoV from EXIF data. Various tools give different results, but which one is right? Here's what I learned, maybe you'll find it useful, too.

Wikipedia states (http://en.wikipedia.org/wiki/Angle_of_view) that for standard rectilinear lenses the FOV is calculated by using this formula:

FOV = 2 arctan ( image area size / (2*focal length))

So if you want horizontal, vertical or diagonal FoV, you simply use horizontal, vertical or diagonal image area size, respectively. With digital cameras the image area is actually CCD sensor size, and Fuji's specs for 10538's camera (FinePix2800ZOOM) list its CCD sensor as 1/2.7-inch with 2.1 million pixels. By 1/2.7" they are referring to an old (since 50's) TV camera tube standard (http://www.dpreview.com/learn/?/key=sensor%20sizes) size, with the following dimensions:
:
Type Aspect Dia. (mm) Diagonal Width Height1/2.7" 4:3 9.407 6.721 5.371 4.035
By using 5.37mm sensor width and 6mm focal length from the above image, I get the same value of HFoV like you did in 3DS: 48.217Â°. However, it seems that CCD manufacturers don't really use those standard sizes, and I've learned that the actual size of CCD sensor used in 10538's camera is 5.27 x 3.96 mm. Calculation for this value with 6mm focal length returns the following HFoV: 47.419Â°.

But I've also learned that neither of this values is actually correct, as not all of CCD's 2.1 million pixels are used in the resulting image - 10538's camera uses only 1.9 million effective pixels, so the effective sensor size used for calculation should be even smaller. But then where did EXIFtool get its, as I'm aware now - completely wrong value of 48.9 degrees? I've analyzed its source code and I believe I've identified the problem - wrong value is calculated only for non-35mm cameras with aspect ratio of 4:3 - and I'm going to write to the author to correct this. However, after studying the source code now I know how to do it manually. Here's what you need for manual FoV calculation (actual data from 10538's image):

Focal Plane X Resolution        : 3053
Focal Plane Y Resolution        : 3053
Focal Plane Resolution Unit     : cm
Image Width                     : 1600 px
Image Height                    : 1200 px
Focal Length                    : 6.0 mm

The first three values hide the key to the true effective size of the imaging sensor. The same value for both X and Y plane focal resolution is normal for square pixels, so we can use either value to calculate the size of a single pixel. With indicated centimeter as resolution unit, this is done by dividing 10 with 3053 = 0,0032 millimeters/pixel. If it were inches, we would divide 25.4 with the focal resolution value for the same result.

The rest is easy:
0.0032 x 1600 = 5.24mm (effective horizontal image area size)
0.0032 x 1200 = 3.93mm (effective vertical image area size)
Horizontal FoV = 47.179Â°
Diagonal FoV = 57,254Â°
Vertical FoV = 36,267Â°

This should finally be the correct values, but I'll still double check them with my camera (also Fuji) to see how much precision can actually be achieved this way.
: Re: Chad pictures
: 10538 May 29, 2008, 03:53:17 PM
I assume that laser measurements were also done from that exact same spot?

Yes, same exact spot.  Sorry about the crappy camera.  It turns out 11aug's camera is 4x the res as mine.  Luckily I set it to the highest res or it would have been worse.

: Re: Chad pictures
: spf33 May 29, 2008, 04:06:12 PM

The rest is easy:
0.0032 x 1600 = 5.24mm (effective horizontal image area size)
0.0032 x 1200 = 3.93mm (effective vertical image area size)
Horizontal FoV = 47.179Â°
Diagonal FoV = 57,254Â°
Vertical FoV = 36,267Â°

screenshot of max fov calculations;

(http://img403.imageshack.us/img403/8688/maxfov01al6.jpg)

: Re: Chad pictures
: nekitamo June 01, 2008, 06:23:54 PM
I got a confirmation from the author of EXIFTool - he acknowledged that his FOV formula is not correct for 4:3 aspect ratio cameras, but as most professional cameras use 3:2 aspect and the error is below 5%, he won't exactly "rush" to fix it.

Also, I've just finished my calculations for the first image and although I'm still preparing the description of the second part for posting here, I believe there's no need to keep the results hidden in the meantime. Here's the calibration image with a perspective-correct 3D ruler drawn between the two reference points:

(http://img110.imageshack.us/img110/5339/4final1zh5.jpg)

And here's the same ruler translated into the perspective of Chad's image based on the assumption that both small fins in line with the ruler are of the same length (4.2m):

(http://img148.imageshack.us/img148/2182/4final2uy6.jpg)

As you can see, the final result doesn't differ much from my preliminary estimation - the outer diameter of the central ring is again close to 4 meters.
: Re: Chad pictures
: spf33 June 05, 2008, 03:03:40 AM
very preliminary here, just thought you all might be interested in the progress;:

i used all the regular exif and manufacturer info to set this up with the plan to transfer most of the assets to a scene using chad's original 1169x767 scannedimage.jpg.
anyone have any idea what 1169x767 might be natively?  i know all chad's image photos, minus the cell phone, are about the same resolution so i am wondering if anyone knows what native res they all are cropped from.

the 3d scene using chad's image, i'm really going to have to wing it as far as fov, ccd sensor size and lens so even a good guess on the native res will help.

: Re: Chad pictures
: nekitamo June 05, 2008, 08:43:32 AM
Not sure what you mean, but Chad's images fit the profile of i.e. 4.0" x 6.0" (3:2 aspect ratio) photographs scanned at (1169/6=) 200 dpi, then slightly cropped to hide margins. In this case 1169x767 could very well be the original, unresized image produced by the scanner.

While I was calculating my ruler translations I deduced the horizontal field of view angle for #4 to be around 35 degrees, but I believe it would be better if you don't use my findings so we can have two independent analysis eventually producing the same results :)
: Re: Chad pictures
: nekitamo June 05, 2008, 09:40:42 AM
Looking at Spf33's work reminded me about another thing I wanted to ask, not to mention that spf probably needs this information, too.

So, if you don't mind: exactly how tall are you, elevenaugust?  :)
: Re: Chad pictures
: onthefence June 05, 2008, 12:37:07 PM
So, if you don't mind: exactly how tall are you, elevenaugust?  :)

I think you would also need to know 10538's height to determine the angle of the camera with respect to the ground.

Which leads me to the question of angles and elevation. Would it help in your calculations to use surveyors equipment for all this photo analysis. I mean to determine the angle of objects in the sky relative to their plane against the ground, you should be given the angle of horizon as well as the actual on-site field of view angles.

I mean, is there a camera or attachment that will give you the following information, blue = angle of elevation, red = dots or rings showing actual angles in the field.

(http://i294.photobucket.com/albums/mm106/onthefence55/angles.jpg)

Something like this would come in very handy especially for Stephens site, where low resolution and possibly inaccurate USGS elevation maps are relied upon.
: Re: Chad pictures
: spf33 June 05, 2008, 01:07:25 PM
heh.  nekitamo, it's like walking down the same path a few steps behind you.
i too was going to ask how tall tonio is but forgot to in my excitement to post that last chad image showing the tilted drone.

onthefence, heck yes equipment that gives height and angle would incredibly helpful i'm discovering.

still not sure if the usgs dem for stephen i'm using contains errors or not.

http://data.geocomm.com/catalog/US/61069/1688/group4-3.html
and here's the link to the bit about positional errors:

not sure how i can determine if the dem i'm using were created before 2001 thus were corrected and the errors introduced.  think i might have to email and ask.

*edit to add -  here's my post on the geocommunity website asking for clarification on the dem errors.  sent an email to their help email account also:

http://spatialnews.geocomm.com/community/boards/viewpost.php?cat_id=2&mess_id=9214
: Re: Chad pictures
: elevenaugust June 05, 2008, 01:52:56 PM

So, if you don't mind: exactly how tall are you, elevenaugust?  :)
I was waiting for this question!!
My height is 1.77m  :)
: Re: Chad pictures
: nekitamo June 05, 2008, 02:53:37 PM
Thank you :)

But, here's another thing... I did some tests with my camera to check the accuracy of FoV angle calculated from EXIF data, and the result is pretty discouraging:

(http://img390.imageshack.us/img390/3277/fovanglegc6.jpg)

I believe this is mainly due to barrel/pincushion distortion which also varies with focal length. I'll try to devise some means of "calibration" in order to deal with this anomaly...
: Re: Chad pictures
: spf33 June 05, 2008, 03:53:32 PM

My height is 1.77m  :)

i had you at 5 inches taller.
so i'll have to rotate the camera down a little which shouldn't change the needed drone tilt too much.

nekitamo, i'll also redo this scene with whatever fov estimations we can come up with.

...photographs scanned at (1169/6=) 200 dpi, then slightly cropped to hide margins. In this case 1169x767 could very well be the original, unresized image produced by the scanner.

how did you determine the photos were scanned at 200dpi?
also, looking at chad's ScannedImage-5.jpg the size is 1171, not that i think 2 pixels are going to make all that much difference but i would like to be able to use the native res.

i'm not sure i understand your fov graph, can you explain further?
since max also calculates the same fov's you are getting, that would mean max is susceptible to these errors(?).

: Re: Chad pictures
: 10538 June 05, 2008, 04:32:34 PM
very preliminary here, just thought you all might be interested in the progress;:

Very impressive Spf.  I had no idea the drone would have to be so close to the tree.  Do you need any camera data from me?  Let me know.
: Re: Chad pictures
: nekitamo June 05, 2008, 04:51:36 PM
how did you determine the photos were scanned at 200dpi?

Well, by simply dividing the number of pixels with the supposed image size. So if it was 6" wide photograph, 1169/6=194.8 pixels/inch = 200 dpi. If the photo was smaller, more dpi was used and vice versa...

i'm not sure i understand your fov graph, can you explain further?
since max also calculates the same fov's you are getting, that would mean max is susceptible to these errors(?).

Actually, I believe the error comes from the camera, and my camera model is known for its substantial barrel distortion at low focal lenghts. Here's how I think barrel/pincushion distortion affects the FoV angle:

(http://img108.imageshack.us/img108/1962/fovangle2xd8.jpg)

Maybe we should ask for some "calibration" shots with various focal lengths of some kind of known-size grid at known distance from the camera?
: Re: Chad pictures
: spf33 June 05, 2008, 05:16:05 PM
I had no idea the drone would have to be so close to the tree.

and i had no idea there was even any tilt just looking at the photo.
but it could be a bit farther from that tree than i have in 3d.
i didn't even check the dimensions of the drone torus in the 3d until right now...4.2 meters.

unless a hoaxer did exactly what we are doing here, distance measurements, satellite views, terrain data, camera exif data, 3d photogrammetry, i can't see them getting these tilts correctly and consistently or even at all.  does that make sense?

at this point, the tilting which at first seemed fishy is beginning to point to authentic photos for me...but this feeling may change.

hopefully chad's scannedimage-2 and 5 are consistent with scannedimage.jpg.
: Re: Chad pictures
: 10538 June 05, 2008, 07:20:11 PM

and i had no idea there was even any tilt just looking at the photo.
but it could be a bit farther from that tree than i have in 3d.
i didn't even check the dimensions of the drone torus in the 3d until right now...4.2 meters.

unless a hoaxer did exactly what we are doing here, distance measurements, satellite views, terrain data, camera exif data, 3d photogrammetry, i can't see them getting these tilts correctly and consistently or even at all.  does that make sense?

Do you mean, with respect to shadows and sun angles?  Or are you talking about visual perspectives?

One thing I am working on is analyzing the sun angles on the drones between the different Chad pics and against the background.
: Re: Chad pictures
: spf33 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.
: Re: Chad pictures
: onthefence June 06, 2008, 04:47:04 PM
Some more Chad site pictures from 11aug:

http://droneteam.com/images/IMG_0931.JPG

http://droneteam.com/images/IMG_0944.JPG
: Re: Chad pictures
: majicbar June 07, 2008, 03:51:10 AM
I see a power pole to the right side of the picture, a nexus on power poles?
: Re: Chad pictures
: nekitamo 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.
: Re: Chad pictures
: spf33 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.

: Re: Chad pictures
: nekitamo 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:

: Re: Chad pictures
: spf33 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.

: Re: Chad pictures
: 10538 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.
: Re: Chad pictures
: spf33 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...

: Re: Chad pictures
: 10538 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 (http://droneteam.com/images/IMG_0931.JPG)
The shrub on the left is about two or three feet tall.

: Re: Chad pictures
: majicbar 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.
: Re: Chad pictures
: 10538 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!
: Re: Chad pictures
: majicbar 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.
: Re: Chad pictures
: tomi 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.
: Re: Chad pictures
: spf33 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. "
: Re: Chad pictures
: 10538 June 10, 2008, 04:12:06 PM
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.

No exif for those.  They are scans.  Going by the shadows and using the Navy sun angle chart, I would guess it would be about 3:00 pm.
: Re: Chad pictures
: tomi June 10, 2008, 05:33:25 PM
Send me exactly what you want to ask him in a PM and I will copy it and send it to him.  In other words, you specify the questions and I will send them on.
: Re: Chad pictures
: Kaelos June 10, 2008, 06:24:06 PM
Thanks for your work, a very important question...

Please, is it possible to give on a Google sight:

the exact orientation of chad's drone as seen on pictures (tail/ring) ?

A correlation with meridian, fault etc. could be done!

Same question for Raj and Ty of course...

Thanks
: Re: Chad pictures
: spf33 June 11, 2008, 03:25:52 PM
In other words, you specify the questions and I will send them on.

will do.  after lengthy phone conversation with the usgs, it was determined
that my questions needed to be fielded to someone with the appropriate knowledge, this person is supposed to return my call sometime thurs or after.  so let me have that conversation and digest it before i can think what to relay to the surveyor.

very cool conversation about the limits of DEM files, stuff i couldn't actually find online, how tree canopys affect data - especially evergreens, about resolutions, and about a new type of data they are incorporating into the ned on the national map seamless server (http://seamless.usgs.gov/) - lidar (http://www.csc.noaa.gov/products/sccoasts/html/tutlid.htm) which if i can figure out a way to get into max should give over twice the resolution being at 3m.

: Re: Chad pictures
: 10538 June 24, 2008, 07:00:53 PM
Can somebody tell how far the drone is from the camera?

Thanks

: Re: Chad pictures
: nekitamo June 26, 2008, 07:35:33 AM
Here's my estimate based on image FoV angle comparison and previously calculated size of the drone:

I assumed some vegetation growth, as you can see through slightly transparent Chad's image, and also included control distance to elevenaugust for comparison.

Btw, those 15m laser measurements in your image seem to indicate that distance measurements were taken from the spot slightly more to the left from the above background image? Judging by the apparent size of those trees/bushes, the one on the left is obviously far more distant than the other.
: Re: Chad pictures
: 10538 June 26, 2008, 04:54:32 PM
Thanks, Nekitamo.

I'm trying to ascertain the feasibility of the shadow on the bush being cast by the drone.

What do you think?

: Re: Chad pictures
: majicbar June 26, 2008, 05:34:45 PM
I'm pretty sure that the drone arm that is causing the shadow is the next one back, if the indicated arm were the one causing the shadow, then the crown antenna would also be casting a shadow on the tree, where the arm back would allow the crown antenna shadow and other shadows from the drone to fall in front of the tree. It might be a good execrcise to establish the time at which the photograph would have been taken to establish the sun azimuth angle to confirm the arm causing the shadow and to reconfirm the drone size.

Another question that comes to mind is the depth of field that is exhibited in this drone photograph, while it does not appear to exceed reasonable values, does the drone show sufficent depth of field given its range in the photograph and the scale of the scene?
: Re: Chad pictures
: 10538 June 26, 2008, 06:32:57 PM
I'm pretty sure that the drone arm that is causing the shadow is the next one back, if the indicated arm were the one causing the shadow, then the crown antenna would also be casting a shadow on the tree, where the arm back would allow the crown antenna shadow and other shadows from the drone to fall in front of the tree.
Yes, I'm open to that possibility.  My concern is that the angle of the shadow is not consistent with the other arm.  The shadow would be pointing more away from the camera it would seem.  I also considered the crown.  It could be that only the tip or outer half of the arm is casting a shadow that we can see in the photo.  Because the bush has a more vertical side, the shadow is elongated.

It might be a good exercise to establish the time at which the photograph would have been taken to establish the sun azimuth angle to confirm the arm causing the shadow and to reconfirm the drone size.

Another question that comes to mind is the depth of field that is exhibited in this drone photograph, while it does not appear to exceed reasonable values, does the drone show sufficient depth of field given its range in the photograph and the scale of the scene?

Agreed.  I think the exif from our photos would help in determining angle and azimuth.

: Re: Chad pictures
: BigFnTuna June 26, 2008, 07:05:14 PM
Another question that comes to mind is the depth of field that is exhibited in this drone photograph, while it does not appear to exceed reasonable values, does the drone show sufficent depth of field given its range in the photograph and the scale of the scene?

Just a quick note, using Pythagorean, the drone looks to be 27-30 meters away and a similar height off that line of sight, IMO...

Tuna
: Re: Chad pictures
: nekitamo June 29, 2008, 11:19:47 AM
I'm trying to ascertain the feasibility of the shadow on the bush being cast by the drone.
What do you think?

I didn't consider this likely, but after some crude analysis it seems you could be right:

But here's something that we should double check before attempting serious 3D analysis: if I've correctly identified the tree marked with 85m in this mapquest aerial image, note that it is much closer to Chad's position than indicated - so perhaps the detectives used some other spot for their measurements (somewhere on the edge of drawn red circle)?
: Re: Chad pictures
: onthefence June 29, 2008, 11:44:16 AM
I didn't consider this likely, but after some crude analysis it seems you could be right:

One fin position should be moved.

: Re: Chad pictures
: nekitamo June 29, 2008, 11:55:41 AM
You're right, I didn't notice this - a flaw of the 3D model used (by goobermaster@OMF (http://lucianarchy.proboards21.com/index.cgi?action=viewprofile&user=goobermaster)).

: Re: Chad pictures
: Kaelos June 29, 2008, 06:13:42 PM
Thanks Nekitamo and OTF!

Could you give the exact orientation of the drone...on this picture and also on the others?

May be we could do a correlation with ground particularities like: meridian, fault, water, trees, roads, hightways... and what we could imagine!

Great thanks for your work!
: Re: Chad pictures
: leviathan June 29, 2008, 06:20:59 PM
Wonderful work from people who know what they are doing.
IC
: Re: Chad pictures
: nekitamo June 29, 2008, 08:16:30 PM
Could you give the exact orientation of the drone...on this picture and also on the others?

May be we could do a correlation with ground particularities like: meridian, fault, water, trees, roads, hightways... and what we could imagine!

Not sure about exact orientations, but here's what I figured out so far (with image numbers per elevenaugust's notation):
(http://img147.imageshack.us/img147/6440/hwy17possq9.jpg)

EDIT: This is just a quick sketch - for better precision, check sp33's 3D study below!
: Re: Chad pictures
: Kaelos June 30, 2008, 08:12:46 AM
Thanks Nekitamo!

This shows roughly a 15Â° inclination over equator, if we assume the tail/ring is in line with drone trajectory
(that seems to be the case with Chad's drone but not with Raj's one!)

A simple suggestion...
(I'm too busy now for more)

We have dates and locations for Yosemite, Tahoe, Chad, Raj, Brent etc. and a system to determine orientation trajectory (or the field orientation used, like for sail), with ring/tail oriented drone system, perhaps Roy's Dutton theory is applicable there?...

In 1997, Roy Dutton, a NASA orbit calculation specialist, has 'shown' that UFO sightings which seemed not to be correlated, were in fact correlated by a mother ship orbit.

To 'deliver' and 'retrieve' a probe, the mother ship must use a 'super orbit' to come near earth, these orbits make a special angle with equator (101 'markers' identified on equator) and thus sightings are 'spots' on 'lines' defined by orbit/date/location.
(Roy Dutton seemed to be able to make some previsions...)
: Re: Chad pictures
: spf33 June 30, 2008, 03:27:55 PM
still really rough camera matching using chad's scannedimage,
scannedimage2, scannedimage5.

using sensor width of 5mm cameras match photos at what is
working out right now to lens&fov of 5.5\48, 6\45, 6.9\39.

edit to add - the drone is 13.5' wide.  the terrain geometry still isn't finalized at all, not sure yet how much this could alter the results.  the drone arms need to be re-positioned more closely match to the photos (right now it appears the arms may be changing position between photos by slightly horizontally rotating around the center torus).

also, notice scannedimage2 camera and the dramatic foreshortening that doesn't quite match the photo.
: Re: Chad pictures
: spf33 June 30, 2008, 06:02:10 PM
curious as to how long it takes @ an average walking speed of 2.7mph.
with the assumption that scannedimage.jpg thru scannedimage5.jpg were shot successively the drone
would also be moving at around 2.5 -3.5 mph.  the entire walk takes about 2m16s;

: Re: Chad pictures
: Nemo492 June 30, 2008, 06:13:12 PM
Moving from Starting point - Spot 1 - to Spot 2
the photographer had to enter a private property.
Numbers and/or Tonio could better explain that point.
: Re: Chad pictures
: 10538 June 30, 2008, 06:55:20 PM
Just to clear something up.  None of the Chad photos were taken on the lower gravel road. It's more like this:

Plus there is not much of a chance to walk the path indicated by Spf because there is a locked security gate before you get to the lower gravel road.  That and the guard dog (Torco) might get you.
: Re: Chad pictures
: 10538 June 30, 2008, 07:17:35 PM
I should clarify location 3.  It's not certain.  There were not enough landmarks to be certain.  It is also a possibility that 3 and 4 were taken from the same spot, likely looking more toward the east judging by the sun hitting the side of the drone.
(http://home.comcast.net/~dl1027/files/object/loc4.jpg)
(http://home.comcast.net/~dl1027/files/object/loc4-1.jpg)
: Re: Chad pictures
: spf33 June 30, 2008, 07:21:47 PM
None of the Chad photos were taken on the lower gravel road.

assuming consecutive shots, what would be the ideal\available path from 2 to 4 or vice versa?
i don't even know that this matters, might be too much speculation...

: Re: Chad pictures
: 10538 June 30, 2008, 07:29:58 PM
assuming consecutive shots, what would be the ideal\available path from 2 to 4 or vice versa?
This is the only way I see that's feasible.

: Re: Chad pictures
: spf33 June 30, 2008, 07:48:03 PM
This is the only way I see that's feasible.

thanks for that.

so it just reoccurred to me that chad said the cell phone photo was from his wife and that the next time he went out and snapped the other photos he was with a friend.

i guess two men are going to move a bit faster than my pregnant lady estimation of less than 3mph walking speed.

now wondering at what point they may have gotten directly under the drone for scannedimage3 because chad in his testimony seems to imply all the scanned image photos were from the same outing.

: Re: Chad pictures
: 10538 June 30, 2008, 08:02:47 PM
now wondering at what point they may have gotten directly under the drone for scannedimage3 because chad in his testimony seems to imply all the scanned image photos were from the same outing.

Maybe like this:

Still, they would be taking their chances going down there.  But considering the circumstances they may not have been concerned with that.

: Re: Chad pictures
: spf33 June 30, 2008, 08:35:56 PM
Still, they would be taking their chances going down there.

so that road over to the water reservoir is accessible even if private, no fence or gate?

and is the lower path area, below #2, fenced in with torco the killer canine inside?

why the heck is there even helicopter landing pad out here?
: Re: Chad pictures
: Nemo492 June 30, 2008, 08:41:12 PM
While Numbers is away.. i heard the helicopter landing pad story
it was donated by someone
who lost family lives in a car accident...
and it's located by the highway.
There, to the right :

(http://ovnis-usa.com/images/Davis_TVreporters_small.jpg)
: Re: Chad pictures
: 10538 June 30, 2008, 08:55:27 PM

so that road over to the water reservoir is accessible even if private, no fence or gate?
I'm sorry.  I'm trying to go by memory (which is terrible).  I don't recall there being a gate on the path to the water tank.  Actually we saw the tank but never walked over to it.
and is the lower path area, below #2, fenced in with torco the killer canine inside?
There again my memory is fuzzy.  Maybe 11A can remember better.  On second thought, I'm not totally sure there is a gate before getting to the lower gravel road area.  I think you can walk down there, but we have no evidence that any pics were taken from down there.  I think not.  The dog is not fenced in.  You go down there and you risk a confrontation.  It happened to 11A and I when we went to the mouse house area.  None of them dogs are fenced or on a leash.
: Re: Chad pictures
: elevenaugust June 30, 2008, 09:47:32 PM