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Topic: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-05 11:25:55 and read 5834 times.

All,

I was processing an image just now and finally decided to start a debate concerning something that's concerned me for a while now.

It's good form to use verticals to level a shot, but as we know some are more reliable than others. Light-poles and other 'loose' structures aren't effective and often even some larger, more stable structures aren't either.

This shot recently gave me a bit of a headache...


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Photo © Karl Nixon



I always level using the original, full-size file for accuracy. Now using the buildings in the background the shot looked positively unlevel - so much so that I was advised in the feedback forum to use the apron as opposed to the verticals (pretty much unprecedented I know and certainly contrary to house rules). The re-edit looked far better but I found the unlevel buildings a touch distracting - as did whoever screened it as it was rejected for 'level'. Accepted on appeal but it does beg a very important question: are we aiming for technically level or aesthetically level?

One thing I've noticed over the past few years is just how 'out' steel hangars can be - you know, the 'Meccano' type that look as though they were thrown up overnight. Which brings me to the image I was processing a few minutes ago...

http://www.airliners.net/addphotos/b...0.9107hb-jzu_ema_040113_kn_303.jpg

Levelled using an example of one of those flimsy hangars. Now if you look at the main landing gear you can clearly see this interpretation of level puts the aircraft on a starboard-to-port slope, with the aircraft 'listing' (to use a nautical term) to the left. But given that this is a wide-angle shot the verticals of the hangar suggest that this image requires CW rotation, as the perpendicular lines of the structure lean inward more at the right frame-edge than they do at the left. Knowing that the ground at this location is perfectly level I can only conclude that the hangar is the rogue factor here. But in which direction should we be looking in situations like this? What proportion of viewers will deem the image unlevel due to the ground and what proportion level by the hangar?

I'm not looking for a 'this is right, that is wrong' approach as I believe this is entirely down to opinion and preference. There can be no right or wrong. But it does open an interesting debate as to how level is perceived here - and offers sympathy and justification to those who may have had images akin to my examples rejected.

Karl

Topic: RE: To Level Or Not To Level......
Username: mjgbtv
Posted 2013-01-05 12:26:12 and read 5811 times.

Quoting JakTrax (Thread starter):
look at the main landing gear you can clearly see this interpretation of level puts the aircraft on a starboard-to-port slope

How do you level using the main gear? Unless the camera is at the same height as the gear won't perspective make the more distant gear look higher when it is lower than the camera?

In my opinion if it the aircraft looks 'right' and there is no obviously contradictory fixed reference then that should be good enough.

Marty

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-05 12:28:41 and read 5810 times.

Quoting JakTrax (Thread starter):
I was advised in the feedback forum to use the apron as opposed to the verticals (pretty much unprecedented I know and certainly contrary to house rules

Say what?!

My method of leveling always starts with the horizon and figuring out where the "imaginary" level horizon is from one side of the frame to the other and use the ruler tool to draw that line and rotate the photo. Then I use verticals to check that it's level and make minor adjustments accordingly.

I don't like starting with verticals because they can continue to indicate "level" after making many rotational adjustments. I cross check verticals and horizontals, starting with horizontals first.

Topic: RE: To Level Or Not To Level......
Username: dendrobatid
Posted 2013-01-05 12:56:31 and read 5797 times.

Quoting Silver1SWA (Reply 2):
My method of leveling always starts with the horizon and figuring out where the "imaginary" level horizon is from one side of the frame to the other and use the ruler tool to draw that line and rotate the photo.

Essentially I do the same but simpler.
I use a crop tool with no presets and set a crop I like. I then drag a side of that cropped box close to the datum I am going to use. Go to the corner of the box then click and rotate until it is level against my datum. Drag the side of the box back and double click on the image and it will be levelled and cropped.
Takes far longer to type than to do. I have used an example that I had saved from a discussion on this same subject quite a long time ago (You may even recognise it)  

How to level


My memory is good (for my age) - the same image has already been discussed here
Talking About Level..... (by JakTrax Apr 26 2012 in Photography Feedback)
Mick Bajcar

[Edited 2013-01-05 13:13:09]

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-05 13:29:50 and read 5776 times.

Quoting dendrobatid (Reply 3):

I've seen you mention that you level and crop in one step before but thanks for showing it in more detail. That's rather brilliant. I could never get the crop tool to be reliable for leveling but now I see how you make it work. Thanks!   

Topic: RE: To Level Or Not To Level......
Username: vikkyvik
Posted 2013-01-05 14:56:40 and read 5725 times.

Quoting JakTrax (Thread starter):
Levelled using an example of one of those flimsy hangars. Now if you look at the main landing gear you can clearly see this interpretation of level puts the aircraft on a starboard-to-port slope, with the aircraft 'listing' (to use a nautical term) to the left.

That doesn't make a whole lotta sense, as mjgbtv pointed out. Unless your camera is at exactly the same level as the bottom of the main gear, or you're directly in front of or behind the aircraft, they will "appear" to slope to one side or the other.

In the case of your image, it appears your camera is above the gear, so the gear should appear to slope down to the aircraft's left (the viewer's right).

Quoting Silver1SWA (Reply 4):
I've seen you mention that you level and crop in one step before but thanks for showing it in more detail. That's rather brilliant. I could never get the crop tool to be reliable for leveling but now I see how you make it work. Thanks!

Heh, same here. Never figured out how to do that. Seems so simple....

Thanks Mick!

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 05:52:50 and read 5605 times.

Quoting vikkyvik (Reply 5):
Unless your camera is at exactly the same level as the bottom of the main gear, or you're directly in front of or behind the aircraft, they will "appear" to slope to one side or the other

You're talking partially about the rules of plane of vision here; and whilst I agree that the starboard MLG should from this angle be slightly higher, it shouldn't be as high as it is in relation to the port MLG. Having studied a few of my images from this position it is clear that the hangar behind is doing funny things. The aircraft in my example does appear to be on an unnatural incline, sloping from starboard to port.

Another good example is the huge BA hangar at LHR, which crops up in the background if you shoot from the Cains Lane spot on the A30. This structure certainly isn't level, and although you can get your images to 'feel' level I've often wondered what true level actually is here.


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Photo © Karl Nixon



Like I say, I'm not looking for advice or explanations. I rarely get level rejections and have a very keen eye for this sort of thing. I guess I'm seeking to collect opinions on whether the EasyJet shot is level; an experiment to see who comes up with what.

Cheers,

Karl

Topic: RE: To Level Or Not To Level......
Username: je89_w
Posted 2013-01-06 07:22:30 and read 5580 times.

Quoting JakTrax (Reply 6):
I guess I'm seeking to collect opinions on whether the EasyJet shot is level; an experiment to see who comes up with what.

Feels right. To be frank, I think you're over-analyzing this a bit too much.

Topic: RE: To Level Or Not To Level......
Username: ptrjong
Posted 2013-01-06 07:45:29 and read 5569 times.

Hi Karl.

For me, there's not too much difference between what's right and what the screeners think is right, especially in leveling - generally speaking I have a healthy repect for their eye of judgement.

Based on my experience I would immediately pick the apron line as a horizontal on the Merlin shot, and for the Easyjet shot I would carefully select a central vertical - I'd say it needs some CCW but not sure.

Using plane parts at camera level works for this type of shots.

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Photo © Peter de Jong



I don't get many level rejections, but there are photos where I'm clueless about leveling, and I sometimes end up not uploading them.

Peter 

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 07:46:44 and read 5569 times.

Quoting je89_w (Reply 7):
Feels right. To be frank, I think you're over-analyzing this a bit too much

Indeed. But that's the point. I'm just trying to determine whether anyone else sees what I do. Yes, it's very marginal but it's something I pick up on every now and again. I'm not looking for advice or critique - I just find it interesting that each individual sees things slightly differently.

There exist images which no-one will ever be able to say with any certainty are level or unlevel. For me my example is kind of odd because it looks level by certain references but not by others. I honestly can't say whether I think it LOOKS level or whether it FEELS level.

Strange.....

Karl

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 07:54:02 and read 5566 times.

Quoting ptrjong (Reply 8):
I'd say it needs some CCW but not sure

Yes, there are times when I look at it and think the same. The slight 'list' from starboard to port seems to suggest CCW needed - but the verticals of the hangar appear to hint towards CW (taking the lens distortion into account). The vertical at the right edge of the frame leans inwards much more than the one at the left (the latter actually looking almost perfectly perpendicular).

It's a funny old business is levelling! Goes to show, sometimes it has to 'feel' right rather than actually be right.

Karl

Topic: RE: To Level Or Not To Level......
Username: dendrobatid
Posted 2013-01-06 08:51:32 and read 5552 times.

Quoting ptrjong (Reply 8):
I don't get many level rejections, but there are photos where I'm clueless about leveling, and I sometimes end up not uploading them.

Peter
Your comment made me laugh.
As I am sure you are aware I like to get new stuff for the database and this one is not on.
Now try and level it - I have given up !
I wonder how anyone would get on with it and have attached it big enough for anyone to have a go  

Mick Bajcar

Try and level this one!

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 09:04:31 and read 5547 times.

Mick, that's precisely the kind of example I'm talking about. My point being: how the hell is anyone going to know when that's truly level??? All about the 'feel' I guess but since we each interpret that differently.......

It also appears that - despite any barrel distortion - there are some very unlevel structures in that hangar!!!

Karl

Topic: RE: To Level Or Not To Level......
Username: AlexC
Posted 2013-01-06 09:28:14 and read 5541 times.

By the looks of that one Mick you should have had time to put the camera on the tripod and level it by using a spirit level in the hot shoe. No argument's then! OK, so that's going a bit too far in this instance, but I often used to do that taking shots of buildings with a PC lens to avoid converging verticals which makes them appear to be falling over backwards.

Alex

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 09:53:28 and read 5527 times.

Quoting AlexC (Reply 13):
but I often used to do that taking shots of buildings with a PC lens to avoid converging verticals which makes them appear to be falling over backwards

All very well - until you get to Lukla - or even Birmingham's 'roller-coaster' runway!


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Photo © Karl Nixon



Karl

Topic: RE: To Level Or Not To Level......
Username: mjgbtv
Posted 2013-01-06 10:09:59 and read 5522 times.

Quoting dendrobatid (Reply 11):
I wonder how anyone would get on with it

I would give it some CCW. I don't know much about construction, but I believe that leveling is fairly important with bricklaying so I would trust the verticals on that wall more than the steelwork. I think it would also 'feel' right with some CCW.

Marty

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 10:20:58 and read 5519 times.

Quoting mjgbtv (Reply 15):
but I believe that leveling is fairly important with bricklaying so I would trust the verticals on that wall more than the steelwork

I'd agree but I doubt anyone could argue with the fact that even the most solid of structures can lose their shape or otherwise shift over time.

Like me I think Mick is just putting forward another example as opposed to seeking advice on how to level. Let's face it - it'd be a tough challenge for anyone to technically perfectly level his shot!

I guess the purpose of this thread is to demonstrate just how unreliable the structures upon which we rely on the most truly are.

Karl

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-06 11:21:37 and read 5503 times.

Quoting JakTrax (Reply 16):
Like me I think Mick is just putting forward another example as opposed to seeking advice on how to level. Let's face it - it'd be a tough challenge for anyone to technically perfectly level his shot!

Sounds to me like Mick offered the shot for anyone willing to give it a go.

I'm away from my editing computer for a few hours but upon first glance I think his shot needs quite a bit of CCW rotation. I can tell just by looking at the floor and confirmed by the brick work and the window.

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-06 12:21:06 and read 5492 times.

Quoting Silver1SWA (Reply 17):
Sounds to me like Mick offered the shot for anyone willing to give it a go

Possibly. But levelling such a shot will only be someone's perception of what level is and I doubt anyone will come back trumpeting, "Hey, here you go, I got it right". Unless there's a true horizon - i.e. an ocean - level is most often left entirely to interpretation. Sure, we can get somewhere close but there's going to be no right or wrong for Mick's image.

I wouldn't like to start saying what's accurate and what isn't but if it were my image I too would exercise some CCW. But that doesn't mean it'll get it any closer to being dead level. Under such circumstances we can only give advice based on our personal preferences and ideas.

Karl

Topic: RE: To Level Or Not To Level......
Username: ptrjong
Posted 2013-01-06 15:05:41 and read 5466 times.

Quoting dendrobatid (Reply 11):
I wonder how anyone would get on with i

I would try to make equal the slant of the cupboards on the left, and of the verticals on the brick wall on the right.

(It's hard to do for me now since I seem unable to measure angles in PS Elements - is there maybe some internet tool available that can do this?)

Topic: RE: To Level Or Not To Level......
Username: mjgbtv
Posted 2013-01-06 17:46:46 and read 5443 times.

Quoting JakTrax (Reply 18):
there's going to be no right or wrong for Mick's image

I take it that Mick would like to get this image into the database, so that would be the measure of success that matters.

Topic: RE: To Level Or Not To Level......
Username: vikkyvik
Posted 2013-01-06 21:14:17 and read 5414 times.

Quoting JakTrax (Reply 6):
You're talking partially about the rules of plane of vision here; and whilst I agree that the starboard MLG should from this angle be slightly higher, it shouldn't be as high as it is in relation to the port MLG. Having studied a few of my images from this position it is clear that the hangar behind is doing funny things. The aircraft in my example does appear to be on an unnatural incline, sloping from starboard to port.

I understand. I gave it about .15 degrees CW, and it still looked OK to me. But I understand what you're saying.

Quoting dendrobatid (Reply 11):
Now try and level it - I have given up !
I wonder how anyone would get on with it and have attached it big enough for anyone to have a go

Gave it a shot. As mjgbtv says:

Quoting mjgbtv (Reply 15):
I would give it some CCW. I don't know much about construction, but I believe that leveling is fairly important with bricklaying so I would trust the verticals on that wall more than the steelwork. I think it would also 'feel' right with some CCW.

...I think the brick is more reliable, and makes the floor and airplane seem more level as well. I gave it 2 degrees of CCW.

Quoting JakTrax (Reply 18):
Possibly. But levelling such a shot will only be someone's perception of what level is and I doubt anyone will come back trumpeting, "Hey, here you go, I got it right".

Hey, here you go, I got it right  

http://www.vksphoto.com/photos/i-wcqnnxf/1/X2/i-wcqnnxf-X2.jpg

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-07 08:17:36 and read 5339 times.

Vik,

That looks better but if it were my image I'd prefer it with a touch less CCW. I wouldn't even like to think how A.net would prefer it.......

I just found another good example of mine....


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Click here for bigger photo!

Photo © Karl Nixon



At first glance it appears to requite CW; but then when you check the verticals actually indicate that it's level. In fact one even suggests CCW required!

The Airport Hotel is a solid, brick building but it does date from around the '40s so has had a bit of wear and tear.

Karl

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-07 10:02:10 and read 5320 times.

Quoting JakTrax (Reply 22):
At first glance it appears to requite CW; but then when you check the verticals actually indicate that it's level. In fact one even suggests CCW required!

Karl, verticals can be misleading. I can check verticals and they will look straight. Then I can rotate the image .2-.5 degrees and they often still look straight.

Topic: RE: To Level Or Not To Level......
Username: vikkyvik
Posted 2013-01-07 10:30:13 and read 5315 times.

Quoting JakTrax (Reply 22):
That looks better but if it were my image I'd prefer it with a touch less CCW. I wouldn't even like to think how A.net would prefer it.......

I had to estimate it. I measured the verticals on the brick wall, but since it's over to one side, I reduced the rotation a bit. Also wanted to make the floor and airplane look level to my eyes. Pretty much disregarded the steel wall and cabinets in the back.

Quoting JakTrax (Reply 22):
At first glance it appears to requite CW; but then when you check the verticals actually indicate that it's level. In fact one even suggests CCW required!

That one looks perfectly fine to me as it is.

Topic: RE: To Level Or Not To Level......
Username: dendrobatid
Posted 2013-01-07 10:32:35 and read 5329 times.

Quoting vikkyvik (Reply 21):
Hey, here you go, I got it right

About the same as I got it but it still feels wrong to me. Might have another go as the aircraft is not on the db....

Quoting Silver1SWA (Reply 23):
I can check verticals and they will look straight. Then I can rotate the image .2-.5 degrees and they often still look straight.

That is precisely the point. I use the longest straight line be it vertical or horizontal that leaves the image feeling right. We Screeners cannot know the ups and downs of every airfield but we can tell when they feel right and simply glancing at the thumbnail of that Embraer it feels like it needs a little CW. I would not dream of doing that in screening, I would open it but from the thumb (I have not opened it beyond that) I think the guttering of the pub would indicate some CW needed. Try that and I suspect that you will not even be able to notice the difference in the verticals of the pub wall.

In screening I do not even check the level of an image if it feels right. If I check because it feels wrong, it almost invariably is wrong. I have however screened 130000 images now and it did take me a while as an uploader to get to grips with what was needed.

Mick Bajcar

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-07 10:39:46 and read 5326 times.

Quoting Silver1SWA (Reply 23):
Karl, verticals can be misleading. I can check verticals and they will look straight. Then I can rotate the image .2-.5 degrees and they often still look straight.

They sure can! Some buildings simply aren't perpendicular - in fact more often than one might think. Ground levels sink and shift slightly, and foundations/brickwork become worn. I always level using the full-size file, so I can zoom right the way in to check any verticals are perpendicular. In a re-sized edit ~0.3 degrees isn't really noticeable, but it can be when viewing the high-res file.

Fact is, verticals simply aren't reliable enough sometimes - even if there's a number of them and they're quite strong. Add to that a provision for lens distortion and it can become a headache!

Karl

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-07 10:52:12 and read 5351 times.

Quoting vikkyvik (Reply 24):
That one looks perfectly fine to me as it is
Quoting dendrobatid (Reply 25):
glancing at the thumbnail of that Embraer it feels like it needs a little CW

A good example of how we each have a different perspective. To me the Embraer feels wrong (I agree with Mick - especially when viewing the thumbnail alone), but I have to try and second-guess what the screeners will be looking for. The left-hand wall of the pub already actually leans inward (not a wide-angle shot so no barrel distortion) - by a similar amount as those of the garage structure far-right lean outward - so I had to ask myself whether whoever screened it would be looking at those verticals.

Quite often I level for here differently than I level for myself. The ERJ shot would certainly have a little CW if I was printing a large copy for my living room wall - but for here I have to try and satisfy a requirement for the verticals to in some way correspond.

So far this thread is doing its job, in highlighting the fact that we all have slightly different interpretations of level - with, incidently, none of these interpretations actually being wrong.

Cheers,

Karl

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-07 11:17:34 and read 5340 times.

Quoting JakTrax (Reply 26):
They sure can! Some buildings simply aren't perpendicular - in fact more often than one might think. Ground levels sink and shift slightly, and foundations/brickwork become worn. I always level using the full-size file, so I can zoom right the way in to check any verticals are perpendicular. In a re-sized edit ~0.3 degrees isn't really noticeable, but it can be when viewing the high-res file.

You're missing my point. I'm not talking about whether a vertical is in fact perpendicular. I'm saying that the same vertical reference will appear straight through multiple rotational adjustments of the image. The shorter the vertical reference, the more it's true which is why, as Mick stated, always use the longest straight line for your checks.

Let's say, for example, you have a vertical in your photo that you know is 100% perpendicular and you use it as a leveling reference and ignore all other vertical or horizontal references because you KNOW that one vertical is perpendicular. Your photo can still be off because of the unreliability I describe above.

[Edited 2013-01-07 11:29:45]

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-07 11:33:41 and read 5334 times.

I know what you were getting at, I was just adding my own slant (pardon the pun) to it. In my experience if you zoom all the way in (pixel-peep effectively, which is what I do) the longer verticals can be affected by even the slightest rotation. I'd definitely agree that some smaller verticals can remain pretty much unaffected though.

Of course even the most miniscule rotations make a difference - it just depends on how closely you want to inspect the image in oder to see that difference. What matters in a high-res image often isn't significant once it's been resized. I think that's a fair point.

Karl

Topic: RE: To Level Or Not To Level......
Username: AlexC
Posted 2013-01-08 03:15:52 and read 5263 times.

Quoting JakTrax (Reply 14):
All very well - until you get to Lukla - or even Birmingham's 'roller-coaster' runway!

But I was talking about taking photos of buildings, not runways.

Quoting JakTrax (Reply 16):
I'd agree but I doubt anyone could argue with the fact that even the most solid of structures can lose their shape or otherwise shift over time.

Speaking as a building surveyor, I'd be rather worried if the structure had 'shifted over time' to such an extent as to be visible in Mick's photo!

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-08 08:11:48 and read 5240 times.

Quoting AlexC (Reply 30):
Speaking as a building surveyor, I'd be rather worried if the structure had 'shifted over time' to such an extent as to be visible in Mick's photo!

Something has obviously happened, because there's no way that effect can be caused by lens distortion alone. One of those structures clearly isn't standing as it should, and as I said earlier, it's less likely to the the brick building. It harks back to one of my original points about how flimsy these steel hangars are.

As for things shifting, you only have to look at many buildings in Venice, and the Leaning Tower of Pisa - structures that are, I dare say, built much more solidly than some of today's flimsy affairs.

Surely if things didn't shift, there would be little need for a building surveyor? What about these houses that partly collapse into abandoned mine shafts and such like - are you saying that the destruction wouldn't be to such an extent to be visible in a photograph?

Karl

Topic: RE: To Level Or Not To Level......
Username: AlexC
Posted 2013-01-08 11:11:43 and read 5215 times.

The Leaning Tower and the buildings of Venice are special cases. The foundations of Venice are placed on timber piles driven down through the soft mud to the clay layers below, so movement is to be expected. As far as the Leaning Tower is concerned, I believe that it started to lean shortly after it was completed owing to inadequate foundations. They didn't have the structural engineers that we have today! And regarding building surveyors, there's plenty for them to do that doesn't involve 'shifting buildings'!

[Edited 2013-01-08 11:15:45]

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-08 16:05:32 and read 5164 times.

Quoting AlexC (Reply 32):
The Leaning Tower and the buildings of Venice are special cases. The foundations of Venice are placed on timber piles driven down through the soft mud to the clay layers below, so movement is to be expected. As far as the Leaning Tower is concerned, I believe that it started to lean shortly after it was completed owing to inadequate foundations. They didn't have the structural engineers that we have today! And regarding building surveyors, there's plenty for them to do that doesn't involve 'shifting buildings'!

Just to mention, I wasn't professing to know more about your job than you do - I was simply saying that wear and tear on structures can obviously warp and distort them (particularly flimsy steel hangars). There were cases very recently in my locality of a series of houses partially collapsing into old mine shafts. Whether it be down to bad planning/building I don't know but it happens.

Hangars are never built lop-sided but that's quite often how then end up. How else can Mick's shot be explained?

Karl

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-08 16:17:36 and read 5160 times.

Quoting JakTrax (Reply 33):
Mick's shot be explained?

Well, hard to tell from this photo alone but perhaps there's something with the design of the hanger that is throwing us off?

Topic: RE: To Level Or Not To Level......
Username: vikkyvik
Posted 2013-01-08 18:51:15 and read 5143 times.

Quoting Silver1SWA (Reply 34):
Quoting JakTrax (Reply 33):
Mick's shot be explained?

Well, hard to tell from this photo alone but perhaps there's something with the design of the hanger that is throwing us off?

Looks to me like it's a slanted roof (for drainage, I assume), and the metal wall is perpendicular to said roof, for whatever reason. Like they couldn't find, or didn't want to be bothered making, a properly angled joint.

Topic: RE: To Level Or Not To Level......
Username: Silver1SWA
Posted 2013-01-08 19:53:51 and read 5134 times.

Quoting vikkyvik (Reply 35):
Quoting Silver1SWA (Reply 34):
Quoting JakTrax (Reply 33):
Mick's shot be explained?

Well, hard to tell from this photo alone but perhaps there's something with the design of the hanger that is throwing us off?

Looks to me like it's a slanted roof (for drainage, I assume), and the metal wall is perpendicular to said roof, for whatever reason. Like they couldn't find, or didn't want to be bothered making, a properly angled joint.

Exactly. It looks to me that by design, the metal wall in the back is angled outward instead of perpendicular to the ground.

Topic: RE: To Level Or Not To Level......
Username: AlexC
Posted 2013-01-09 01:53:49 and read 5100 times.

I think that the only way to sort this out is for me to visit this wretched hanger myself and carry out a survey! Anyone know where it is?!!!

Topic: RE: To Level Or Not To Level......
Username: dendrobatid
Posted 2013-01-09 04:16:04 and read 5090 times.

Alex
I might go back there in May and will take a plum bob, spirit level, yellow hat and high viz jacket, oh and a spade to lean on. If you decide to go, send Karl the bill  

It was at Les Mureaux to the North of Paris, very quiet on my visit but I think it must be a very lively place on a good weekend, lots of hangars, mostly locked up but a gentleman stopped shoring the back of this hangar up and opened it up for me  

It seemed a perfectly ordinary hangar until I tried to level the image on my return home.

48°59'49.55"N 1°55'47.90"E

Mick Bajcar

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-09 07:05:21 and read 5055 times.

Those cupboard things at the back lean similarly to the rear of the hangar, so unless they too are designed to stand at an angle there's certainly something odd going on. I imagine lens distortion is playing a part - to a point - but it's certainly not distortion alone in my opinion.

I really have no idea what's actually going on.....

Karl

Topic: RE: To Level Or Not To Level......
Username: AlexC
Posted 2013-01-09 07:59:30 and read 5054 times.

Quoting dendrobatid (Reply 38):
I might go back there in May and will take a plum bob, spirit level, yellow hat and high viz jacket, oh and a spade to lean on. If you decide to go, send Karl the bill

Oh I do like that Mick. You could hold the levelling staff while I take down the readings. And I especially like the bit about presenting Karl with the fee. However, he shouldn't worry too much at least not for the moment as I can't see myself getting over to France in the relatively near future!

Topic: RE: To Level Or Not To Level......
Username: vikkyvik
Posted 2013-01-09 08:15:28 and read 5049 times.

Quoting JakTrax (Reply 39):
Those cupboard things at the back lean similarly to the rear of the hangar, so unless they too are designed to stand at an angle there's certainly something odd going on. I imagine lens distortion is playing a part - to a point - but it's certainly not distortion alone in my opinion.

They look like they're bolted to the (leaning) wall, as they are angled off the floor, too.

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-09 08:37:23 and read 5048 times.

Quoting vikkyvik (Reply 41):
They look like they're bolted to the (leaning) wall, as they are angled off the floor, too

So they appear to be. Only looked at the small version initially. This has to be the hangar design in which case, surely?

Karl

Topic: RE: To Level Or Not To Level......
Username: ZSOFN
Posted 2013-01-10 00:41:58 and read 5000 times.

Here's one to add to the various other techniques here that may come in handy when there really is no easy or obvious way to find somewhere to start - this one's worked for me quite well:

Imagine that the camera is sitting on top of a free-standing pole keeping it off the ground. If you let go of the camera, in which direction does your "gut" tell you it's going to topple over? To the left or right? Our own sense of balance is pretty advanced and largely subconscious and perhaps this technique taps into that - after all, we don't really use visual cues to help us stand straight on two feet.

A bit "out there" but I find it helpful and surprisingly reliable.

Topic: RE: To Level Or Not To Level......
Username: JakTrax
Posted 2013-01-10 07:59:52 and read 4975 times.

Quoting ZSOFN (Reply 43):
Imagine that the camera is sitting on top of a free-standing pole keeping it off the ground. If you let go of the camera, in which direction does your "gut" tell you it's going to topple over? To the left or right? Our own sense of balance is pretty advanced and largely subconscious and perhaps this technique taps into that - after all, we don't really use visual cues to help us stand straight on two feet.

This is pretty much the same logic I guess many of us apply when we talk about an image 'feeling' level. Since we can rarely be sure an image IS actually level this gut instinct is relied upon quite heavily at times.

Karl

Topic: RE: To Level Or Not To Level......
Username: AlexC
Posted 2013-01-13 04:07:38 and read 4878 times.

When I first started taking photos at Old Sarum, near Salisbury, my gut instinct was that the grass landing strip was out of level by quite a bit. There were no buildings in the background, so no verticals, just rolling hills. When I up-loaded my first few shots from there they were rejected for 'level'. I thought next time I go there I'm going to get to the bottom of this, so when I did I took my tripod and hotshoe spirit level with me, put the camera on the tripod and low and behold the landing strip was perfectly level! I think what was fooling me was the sloping hills in the background. So there you have it, gut instinct can be easily fooled!


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