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#1 2007-01-24 01:31:24

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

High depth of field - using APP instead of a tilt lens

Weather is not very fine over here, so that I decided to make some tests about DOF and APP (I'm making the weather an excuse for showing a not so nice image wink )

I stitched a series of shot (using a 36 mm equivalent lens at  f:8) where the focusing distance varied from about 1 foot to infinity. Though there were some white balance (mixed light-sources) and exposure issues, the stitched result was very good both when using Multiband or Smartblend.

Most people think that this kind of image is only possible using a view camera: "Altering the angle of the lens in relation to the film plane by tilting the lens standard back and forth is called lens tilt or just tilt. Tilt is another important movement and is especially useful in landscape photography. By using the Scheimpflug principle, the “plane of sharp focus” can be changed so that any plane can be brought into sharp focus." ( http://en.wikipedia.org/wiki/View_camera ) or a "tilt lens" when a SLR camera is used (very few if any are available for DSLR): http://www.hartblei.com/products/images … shift).jpg


Note: changing the distance setting for the lens I used slightly change the field of view (this is easily visible when the screen on the back of the camera is used to display two shots taken when the camera is on a tripod and the distance setting is changed from infinity to the nearest distance.) It looks like, thought the RMS was not very good, the stitched result didn't suffer...


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Last edited by GURL (2007-01-24 01:40:11)

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#2 2007-01-24 08:33:21

AlexandreJ
Absolute beginner
From: Challes les eaux, France
Registered: 2005-11-14
Posts: 4706
Website

Re: High depth of field - using APP instead of a tilt lens

Oh man, this is so cool. Well done GURL. What a beautiful illustration.

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#3 2007-01-24 10:07:00

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

Re: High depth of field - using APP instead of a tilt lens

Certainly a fine illustration of how APP works but not a fine illustration of the way this can lead to beautiful images!

Here is one of the used shots:


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Last edited by GURL (2007-01-24 10:09:47)

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#4 2007-01-24 11:51:05

AlexandreJ
Absolute beginner
From: Challes les eaux, France
Registered: 2005-11-14
Posts: 4706
Website

Re: High depth of field - using APP instead of a tilt lens

Please georges, make a wiki entry out of this.

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#5 2007-01-24 14:57:07

Al
Member
From: Ann Arbor, MI
Registered: 2006-01-21
Posts: 92

Re: High depth of field - using APP instead of a tilt lens

George is right, one of the coolest ways to use APP is stitching a mix of macro images and more distant ones.


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#6 2007-01-24 15:19:49

[bo]
community overseer
From: Bulgaria
Registered: 2006-05-05
Posts: 1285

Re: High depth of field - using APP instead of a tilt lens

If anyone is up to writing a tutorial - use this page: http://en.wiki.autopano.net/Extended_depth_of_field


Some of my panoramas, posted in the Autopano Pro flickr group.

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#7 2007-01-25 21:46:50

Hondoguy
Member
Registered: 2006-07-15
Posts: 41

Re: High depth of field - using APP instead of a tilt lens

How did you decide where to set focus for each shot and why did you settle on f/8 instead of f/11 or f/16? I assume that the way this works, APP is replacing the out of focus area of one shot with the in-focus area of another?

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#8 2007-01-27 14:51:50

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

Re: High depth of field - using APP instead of a tilt lens

Hondoguy wrote:

How did you decide where to set focus for each shot?

Depth of field and circle of confusion are not easy matters, especially when a digital camera is involved!
My Olympus DSLR have a 10x enlarged preview (aka Live View) so that guessing was quite easy. I decided that:
- using large overlap regions is acceptable
- focusing should be close to the center for each source image

I found the shot I took with infinity setting was useless: hyperfocal setting was enough.

Auto-focus + auto-stitching by APP worked very well (this is a good news) and differences between "auto results" versus "manual focus + manual stitch (that is: using Links Editor, RAW images, Olympus distortion and vignetting corrections, etc)" were not very obvious.

and why did you settle on f/8 instead of f/11 or f/16?

My camera/lens combination causes very visible diffraction at f:22 and f:11 is not that good, f:8 is the nice point.

I assume that the way this works, APP is replacing the out of focus area of one shot with the in-focus area of another?

I found there was no noticeable differences between Multiband results and Smartblend results but this needs more testing. An interesting point is that SIFT is able to place CP on features wich are crisp in one source image but are fuzzy in the other one:


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Last edited by GURL (2007-01-27 14:53:27)

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#9 2007-01-28 11:43:19

JohnM
Member
Registered: 2006-10-31
Posts: 147

Re: High depth of field - using APP instead of a tilt lens

Thanks GURL another very nice contribution.

Those who find this interesting might check out norweegian photographer Mikkel McAlinden: http://www.mikkelmcalinden.com/

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#10 2007-01-28 18:50:04

jef
Member
From: New Zealand
Registered: 2006-03-29
Posts: 53

Re: High depth of field - using APP instead of a tilt lens

Hi All,

If you want to take it a step further, try Helicon Focus. You take 3, 10, whatever number of shots ( I am not sure if there is a limit ) with the same framing, but focus on a different distance for every shot. The program then takes the sharpest parts out of every shot, and combines them to one single shot with complete depth of field. Of course, your 20 shot pano now becomes a 60, or 100 shot pano, and if you want to go for the ultimate perfection, and go for HDR at the same time, then you can multiply it ones more by 3, and you need a bookkeeper at your side in order not to loose track  during the shoot.

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#11 2007-01-31 23:26:25

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

Re: High depth of field - using APP instead of a tilt lens

I made another attempt where the subject is about 10 feet (3 m) from the camera and about 60 cm (2 feet) deep (from the cat nose to end of the cat tail.)
Focal length (35mm equivalent) was 240 mm - aperture was f/8 - depth of field (as found in the EXIF data - I recently discovered this useful info being hidden among many useless or useful ones in EXIF) was 12 cm (4.7").

I stitched 12 shots and found Multiband giving much better results than Smartblend (some improvements of Multiband result are possible using a PSD layered file but differences need an attentive examination.) I can't compare with Helicon Focus but suppose some APP users could be interested in using APP for that kind of images.

Here are some very interesting tutorials or discutions about DOF, COC, diffraction, etc:
DOF: http://www.cambridgeincolour.com/tutori … -field.htm
Diffraction: http://www.cambridgeincolour.com/tutori … graphy.htm
How to take identical images using a compact digital camera and an advanced DSLR (when possible, that is): http://www.luminous-landscape.com/essay … nses.shtml
Résolution, MP, profondeur de champ, décalage MaP (French): http://www.photim.net/nci/discu.php3?co … lmimage#O0
... where I learnt that DOF is independant of the used lens (but is much less visible when a wide-angle lens is used than when a long lens - which enlarge it - is used), that for a given sensor the F stop where the detrimental effect of diffraction begins don't depends of focal length (provided the lens is good enough), that a Canon G7 camera should always being used at F/2 to actually make full use of its 10 MP (but somewhat down-sized) sensor and more.


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#12 2007-02-01 05:05:57

jef
Member
From: New Zealand
Registered: 2006-03-29
Posts: 53

Re: High depth of field - using APP instead of a tilt lens

For a different take on depth of field, have a look at Harold Merklinger's theories in "The ins and outs of focus".
www.trenholm.org/hmmerk/download.html

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#13 2007-02-03 02:37:01

petolino
New member
Registered: 2007-01-28
Posts: 4

Re: High depth of field - using APP instead of a tilt lens

GURL  wrote:

An interesting point is that SIFT is able to place CP on features wich are crisp in one source image but are fuzzy in the other one:

Those CPs look close but not exactly right.

#67 looks to be a couple of pixels lower in the right image than in the left (not so bad),
but #52 is noticeably further right, and maybe a little lower, in the right image.
Was the alignment error in the final stitch about the same size as these CP errors?

I'm a new user of APP, and I'm generally very satistifed with the results.  I have noticed that
SIFT has trouble when trying to match an out of focus image to a sharp one.

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#14 2007-02-03 08:49:32

Chemop
Member
Registered: 2006-05-09
Posts: 26

Re: High depth of field - using APP instead of a tilt lens

How about this one, taken last week in theSW Australia Karri forest!


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#15 2007-02-05 09:28:49

[bo]
community overseer
From: Bulgaria
Registered: 2006-05-05
Posts: 1285

Re: High depth of field - using APP instead of a tilt lens

Hey guys,

I'm trying to reproduce those results, but I must be missing something... For example, a simple in-doors shoot of my desk, 5 100% overlapping photos, taken from a tripod, variable FL. I drop those in APP, detect with no lens correction, choose planar projection, render as Multiband TIFF and the result is no good - parts of the images are mixing in a weird out of focus/in focus mix.

Of course, rendering as PSD with layers and selective deletion of image parts works, but it takes time. Somehow I got the impression Georges got this working in a single click manner?


Some of my panoramas, posted in the Autopano Pro flickr group.

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#16 2007-02-05 10:07:10

AlexandreJ
Absolute beginner
From: Challes les eaux, France
Registered: 2005-11-14
Posts: 4706
Website

Re: High depth of field - using APP instead of a tilt lens

Yes, he managed it because his shoots are not 100% overlapping. So APP made a smooth blend between them achieve by the same way a better depth of field. If all pictures are just stacked upon each other, it can't do it.

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#17 2007-02-05 10:31:04

Panorama fanatic
Member
From: St-Petersburg, Russia
Registered: 2005-12-19
Posts: 710

Re: High depth of field - using APP instead of a tilt lens

There is alghoritm to make DEP blending

1. You need 'smartblend' with support of alpha channel (you plan to make this kind of blender in future)
2. You need to make alghoritm to analyze sharpness of small part of image. This algoritm will build sharpness alhpa channel for each image (additional channel to source alpha channel). Transparency of pixels in this mask will be proportionate to sharpeness of source pixels
3. 'smartblend' will use this mask to build pano with maximum DEP

Similar method can be used for HDRI-smartblend, but with another alhpa cnahhel - quality of pixels's color (pixels value near to 0 and 255 have minimum quality, in range 64-192 - maximum quality)


This is only abstract idea to think

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#18 2007-02-05 10:50:24

AlexandreJ
Absolute beginner
From: Challes les eaux, France
Registered: 2005-11-14
Posts: 4706
Website

Re: High depth of field - using APP instead of a tilt lens

Yes, I know such algorithm. The big limitation actually is in the blender : smartblend doesn't support full alpha channel only pass through (1 or 0, not something in between).
Our multiband blender is aware of full alpha but doesn't have any clever blend. Creating a mask out of sharpness is easy and we could imagine to achieve a true depth of field extender easily this way.

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#19 2007-02-05 13:13:33

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

Re: High depth of field - using APP instead of a tilt lens

Chemop wrote:

How about this one, taken last week in the SW Australia Karri forest!

Showing very close items and very distant ones in the same image is not something usual, neither in painting nor in photography. I feel like having a new tool and now what? so that I like viewing examples of very large DOF images like your's...

bo wrote:

Somehow I got the impression Georges got this working in a single click manner?

For the two examples above I made two versions:
1) a first one (from uncorrected JPEGs) where I let APP minds its own business: the result was not perfect but was much better than when using a single focusing distance
2) a second one (from RAW processed and distortion corrected TIFFs) where I used the links Editor to remove CPs (some CPs were set on the pano-head in the tools example - a very large amount of links was created by APP in the cat example so that suppressing the worst ones helped a lot.) Resulting file was a multi-layer PSD including the multiband stitched pano and each of the aligned source images.

The RMS difference between "auto" version and "manual" versions  is large (from 4 to 1.3 for the "lady on the cat" example (where, probably, too many shots were used.) But, whichever the RMS, I insist that APP "automatic results" are much better  than any of the single shots I did. The higher the distance differences are in the subject the more the automatic result looks useful.

Last edited by GURL (2007-02-05 13:15:47)

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#20 2007-02-05 13:39:00

[bo]
community overseer
From: Bulgaria
Registered: 2006-05-05
Posts: 1285

Re: High depth of field - using APP instead of a tilt lens

I'm not talking about RMS. What I cannot understand is if you did some manual processing (selective deletion on layers) in the "Lady on the cat" shoot? Because I cannot get APP to produce such result automatically and I want to know what I did wrong?


Some of my panoramas, posted in the Autopano Pro flickr group.

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#21 2007-02-05 13:48:35

AlexandreJ
Absolute beginner
From: Challes les eaux, France
Registered: 2005-11-14
Posts: 4706
Website

Re: High depth of field - using APP instead of a tilt lens

To [bo] : what I wrote was obviously written too fast : right sentence here :

"Yes, he managed it because his shoots are not 100% overlapping. So APP made a smooth blend between them achieve by the same way a better depth of field. If all pictures are just stacked upon each other, it can't do it."

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#22 2007-02-05 15:16:52

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

Re: High depth of field - using APP instead of a tilt lens

[bo] wrote:

What I cannot understand is if you did some manual processing (selective deletion on layers) in the "Lady on the cat" shoot?

The short answer is no. I didn't select anything in the layers, only used APP Multiband "Blended Layer".

The long answer is that I made a "manual version" comparing the less crisp parts of the blended result with the source images layers. I found some slight improvements being possible but not very useful: the most blury part was not crisp in any of the source images...

You can see bellow the PS layers palette which shows how the souce images where shot and a JPEG stitch produced by APP where the source images were genuine camera JPEGs and where I didn't used the Links Editor.


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#23 2007-02-05 15:21:31

[bo]
community overseer
From: Bulgaria
Registered: 2006-05-05
Posts: 1285

Re: High depth of field - using APP instead of a tilt lens

Hmm, I did not realize that Georges' photos are not overlapping... I will try again with similar approach.


Some of my panoramas, posted in the Autopano Pro flickr group.

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#24 2007-02-05 17:16:20

GURL
Member
From: Grenoble
Registered: 2005-12-06
Posts: 2221
Website

Re: High depth of field - using APP instead of a tilt lens

In case you missed the link from JohnM to Norwegian photographer Mikkel McAlinden at http://www.mikkelmcalinden.com/ ...


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#25 2007-03-07 15:14:27

[bo]
community overseer
From: Bulgaria
Registered: 2006-05-05
Posts: 1285

Re: High depth of field - using APP instead of a tilt lens

Just a follow up. I inspected closely your last post with the cat in the weekend, when I had time to experiment.

I found that actually your result is as flawed as mine. There are sharp contrast between focused and blurred areas without any transition between them. So, I have not done anything wrong the first time, it's just a matter of luck and even then you get not nearly perfect results.

Even with completely overlapping shots, it is possible to use APP, but you still have to mask and delete layers (partially) in Photoshop.


Some of my panoramas, posted in the Autopano Pro flickr group.

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