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DPChallenge Forums >> Photography Discussion >> OK geometry gurus! Is this picture photoshopped?
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07/09/2009 04:43:01 PM · #1
OK, here's the brainteaser for the day. A week ago I linked a picture by Marc Adamus of punchbowl falls:

//www.marcadamus.com/images/large/Twelve-Years.jpg

In it you will see some nice beams of light from the sun hitting what looks like mist from the waterfall. I was up there last weekend and experienced a tiny bit of this, so I know it's theoretically possible.

If you measure the angle of the beams in photoshop you will get about 55 degrees. Adamus claims to have taken the picture in March, 2009. Using my handy, dandy photographer's ephemeric I see that the sun's highest azimuth in March 2009 is 48.8 degrees at 1:16 PM on 3/31.

So here's the question, and I'm not sure of the answer. Is it possible with the point of view to make the sunrays appear to be coming from 55 degrees when they are coming from 49? My brain tells me it's possible, but I'm not quite sure.

Just a crazy question.

Message edited by author 2009-07-09 16:43:21.
07/09/2009 04:53:19 PM · #2
Looking at the image its horizon does not look straight. 1 degree clockwise rotation levels the water.

Could that be the difference.

image

Cheers

Ron
07/09/2009 04:53:26 PM · #3
Originally posted by DrAchoo:

OK, here's the brainteaser for the day. A week ago I linked a picture by Marc Adamus of punchbowl falls:

//www.marcadamus.com/images/large/Twelve-Years.jpg

In it you will see some nice beams of light from the sun hitting what looks like mist from the waterfall. I was up there last weekend and experienced a tiny bit of this, so I know it's theoretically possible.

If you measure the angle of the beams in photoshop you will get about 55 degrees. Adamus claims to have taken the picture in March, 2009. Using my handy, dandy photographer's ephemeric I see that the sun's highest azimuth in March 2009 is 48.8 degrees at 1:16 PM on 3/31.

So here's the question, and I'm not sure of the answer. Is it possible with the point of view to make the sunrays appear to be coming from 55 degrees when they are coming from 49? My brain tells me it's possible, but I'm not quite sure.

Just a crazy question.


if you assume atmosphere does nothing to light.

//mintaka.sdsu.edu/GF/explain/atmos_refr/bending.html

spend sometime with this page, will give you new angle to thinking.
07/09/2009 04:53:30 PM · #4
geometrically it's possible. what you measured as 55° angle is the 2d view, but what matters is the real 3d angle, so in case the sun was coming a bit from the back the angle will be apparently from a slightly steaper angle even though it really isn't. hard to describe, but yes, i think it's definately possible.
07/09/2009 04:54:12 PM · #5
I've seen situations where the sun is behind a cloud and the rays extend in all directions with the cloud as more or less the center point.

I suppose if it were like that the rays could be coming in from any direction into the scene you see in the link.

But in any case, I wonder why you are concerned about 6.2 degrees of seperation! ;-)
07/09/2009 04:54:25 PM · #6
Yes - the issue is that you are projecting an angle in a 3-D space onto the 2-D photography. The actual math is more than I can do this late in the day, but it's not really difficult. Draw a perspective view of a cube, connect the farthest upper corner to the closest lower corner and you can see the same affect.
07/09/2009 04:56:03 PM · #7
Everything I ever wanted to know about automatically assuming something is wrong with a photo when I look at it, I learned on DPC.

Message edited by author 2009-07-09 17:04:26.
07/09/2009 04:56:12 PM · #8
Originally posted by eqsite:

Yes - the issue is that you are projecting an angle in a 3-D space onto the 2-D photography. The actual math is more than I can do this late in the day, but it's not really difficult. Draw a perspective view of a cube, connect the farthest upper corner to the closest lower corner and you can see the same affect.


well said. that's what i meant.
07/09/2009 04:56:32 PM · #9
I have a question for you Doc,

Does anal retentive have a hyphen?

;-)
07/09/2009 04:57:05 PM · #10
Originally posted by Mephisto:

geometrically it's possible. what you measured as 55° angle is the 2d view, but what matters is the real 3d angle, so in case the sun was coming a bit from the back the angle will be apparently from a slightly steaper angle even though it really isn't. hard to describe, but yes, i think it's definately possible.

This is most likely, IMO. A quick experiment can illustrate it - using two fingers, do a 'V' sign with one finger level with the horizon, the other finger raised up above it, with the fingers perpendicular to your face. Note the angle you percieve. Now rotate your hand so that the horizon finger is still level, but with your fingers pointing away from you more, and note the perceived angle again - it'll seem steeper that it "really" is.
07/09/2009 04:57:53 PM · #11
Originally posted by Manic:

Originally posted by Mephisto:

geometrically it's possible. what you measured as 55° angle is the 2d view, but what matters is the real 3d angle, so in case the sun was coming a bit from the back the angle will be apparently from a slightly steaper angle even though it really isn't. hard to describe, but yes, i think it's definately possible.

This is most likely, IMO. A quick experiment can illustrate it - using two fingers, do a 'V' sign with one finger level with the horizon, the other finger raised up above it, with the fingers perpendicular to your face. Note the angle you percieve. Now rotate your hand so that the horizon finger is still level, but with your fingers pointing away from you more, and note the perceived angle again - it'll seem steeper that it "really" is.


Funny, that's exactly what I did before composing my response!
07/09/2009 05:02:07 PM · #12
Originally posted by Manic:

Originally posted by Mephisto:

geometrically it's possible. what you measured as 55° angle is the 2d view, but what matters is the real 3d angle, so in case the sun was coming a bit from the back the angle will be apparently from a slightly steaper angle even though it really isn't. hard to describe, but yes, i think it's definately possible.

This is most likely, IMO. A quick experiment can illustrate it - using two fingers, do a 'V' sign with one finger level with the horizon, the other finger raised up above it, with the fingers perpendicular to your face. Note the angle you percieve. Now rotate your hand so that the horizon finger is still level, but with your fingers pointing away from you more, and note the perceived angle again - it'll seem steeper that it "really" is.


Why am I suddenly getting REALLY funny looks from everyone in McDonald's?
07/09/2009 05:03:00 PM · #13
Originally posted by K10DGuy:

Everything I ever wanted to know about automatically assuming something is wrong with a photo when I look at, I learned on DPC.


That is funny and unfortunately accurate!
07/09/2009 05:08:07 PM · #14
Yep, definitely possible. Imagine the sun directly behind you and shining through trees into fog in front of you. No matter the angle of the sun to the horizon, the rays you see will be perfectly vertical.
07/09/2009 05:08:31 PM · #15
Thanks guys. I seemed to think that the 2D view of a 3D angle could be warped, but I wasn't positive.

To explain the puzzle, ' . substr('//www.dpchallenge.com/images/user_icon/21.gif', strrpos('//www.dpchallenge.com/images/user_icon/21.gif', '/') + 1) . ' mpeters directed me to this crazy site of rabid Marc Adamus haters who say he lies lots and always claims he does very little to his photos (I think we can tell that's not quite true). Anyway, I got to thinking about those rays and wondered if you could actually "prove" they were not real. It's a really slow day at work...

So step 2 now. Here's a screen shot of the topo map. Given the lay of punchbowl falls, what range of degrees on the compass (not elevation) do you think the sun is coming from to make those rays? The river, on the topo map runs SE to NW, So punchbowl appear to face NW.

' . substr('//images.dpchallenge.com/images_portfolio/40000-44999/40718/120/805878.jpg', strrpos('//images.dpchallenge.com/images_portfolio/40000-44999/40718/120/805878.jpg', '/') + 1) . '

Message edited by author 2009-07-09 17:09:12.
07/09/2009 05:13:29 PM · #16
haha, but can you verify that the log is actually gone? :)
07/09/2009 05:17:13 PM · #17
Originally posted by mpeters:

haha, but can you verify that the log is actually gone? :)


It was cloned out I tell ya! Ya, it was gone amazingly. I did see some cut rounds in the water and no other sign of the log so I don't think it simply "washed out" unless it washed out and was then cut. Oregon Forestry Dept has always had the policy of leaving fallen trees alone. Last year the trail up to the falls washed out and I wonder if someone just didn't take their chainsaw and do the job. It's another conspiracy!
07/09/2009 05:17:40 PM · #18
Originally posted by mpeters:

haha, but can you verify that the log is actually gone? :)

' . substr('//images.dpchallenge.com/images_portfolio/0-4999/1031/120/120984.jpg', strrpos('//images.dpchallenge.com/images_portfolio/0-4999/1031/120/120984.jpg', '/') + 1) . '
07/09/2009 05:20:44 PM · #19
Originally posted by kirbic:

Yep, definitely possible. Imagine the sun directly behind you and shining through trees into fog in front of you. No matter the angle of the sun to the horizon, the rays you see will be perfectly vertical.

It seems this would imply that the only time the angle of the rays would match the azimuth value would be when the sun was exactly 90° to the left or right.
07/09/2009 05:21:06 PM · #20
Originally posted by DrAchoo:

Originally posted by mpeters:

haha, but can you verify that the log is actually gone? :)


It was cloned out I tell ya! Ya, it was gone amazingly. I did see some cut rounds in the water and no other sign of the log so I don't think it simply "washed out" unless it washed out and was then cut. Oregon Forestry Dept has always had the policy of leaving fallen trees alone. Last year the trail up to the falls washed out and I wonder if someone just didn't take their chainsaw and do the job. It's another conspiracy!


I heard marc adamus was seen leaving a corvallis Home Depot with a husquavarna last march.
07/09/2009 05:39:27 PM · #21
i've been thinking about the times when the suns rays are visible and it seems that the only time i've ever seen them is when there is a partial blockage of the sun, either by clouds or trees, etc. and the rays come out at various angles depending on which side of the obstruction you look at. i can't recall ever seeing sun's rays on a completely clear day.
07/09/2009 05:43:42 PM · #22
Originally posted by DrAchoo:

Just a crazy question.


Um...yeah. ;)
07/09/2009 05:57:49 PM · #23
OCD much?

Here's my take on it. You measured 55 degrees as the angle of the rays. I think this is an unreliable measurement.

First, the 'rays' might not be rays at all, but caused by variations in the density of the mist. Secondly, it looks like a long-exposure shot, so any lighting effects/shadows caused during the exposure will be moving during the shot.

07/09/2009 05:57:56 PM · #24
Originally posted by briantammy:

i've been thinking about the times when the suns rays are visible and it seems that the only time i've ever seen them is when there is a partial blockage of the sun, either by clouds or trees, etc. and the rays come out at various angles depending on which side of the obstruction you look at. i can't recall ever seeing sun's rays on a completely clear day.

It can be clear above as long as there is some level of particulates (fog or dust) at the lower levels where you want to see the rays. Here it was a bright clear sky above the hill, but there was enough stuff floating around to show up the rays as broken up by the trees.
' . substr('//images.dpchallenge.com/images_portfolio/0-4999/1031/120/763025.jpg', strrpos('//images.dpchallenge.com/images_portfolio/0-4999/1031/120/763025.jpg', '/') + 1) . '
07/09/2009 05:58:44 PM · #25
Originally posted by DrAchoo:

Thanks guys. I seemed to think that the 2D view of a 3D angle could be warped, but I wasn't positive.

To explain the puzzle, ' . substr('//www.dpchallenge.com/images/user_icon/21.gif', strrpos('//www.dpchallenge.com/images/user_icon/21.gif', '/') + 1) . ' mpeters directed me to this crazy site of rabid Marc Adamus haters who say he lies lots and always claims he does very little to his photos (I think we can tell that's not quite true). Anyway, I got to thinking about those rays and wondered if you could actually "prove" they were not real. It's a really slow day at work...

So step 2 now. Here's a screen shot of the topo map. Given the lay of punchbowl falls, what range of degrees on the compass (not elevation) do you think the sun is coming from to make those rays? The river, on the topo map runs SE to NW, So punchbowl appear to face NW.

' . substr('//images.dpchallenge.com/images_portfolio/40000-44999/40718/120/805878.jpg', strrpos('//images.dpchallenge.com/images_portfolio/40000-44999/40718/120/805878.jpg', '/') + 1) . '


Given the other shadows in the image, I'd guess that the light is coming from his front-left, which, given the map you provided, puts the sun in the southeast. I'd say the shot was probably taken mid to late morning then.
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