Stitching - A Toronto Church Interior Example

[Ed Richards]

I hope folks will not be offended that the original images were from a D600. This is an example of a large, high rez image built by stitching. I have included a link to full size file (95 megs) so that folks who have been interested in what you can achieve this way and how it compares to LF can pixel peep to their heart's content. This was built from 40x2 images - a 40 exposure stitch done with two exposures to control the DR. This was stitched in PTIGui and HDR mapped in Photomatrix.

http://www.epr-art.com/working/Toronto_Church-2.jpg

Full size (95 megs) (http://www.epr-art.com/working/Toronto_Church.jpg)

Nikon D600, ASA 200, 85mm F1.8, f9.5, 0.7 sec and 6 sec. (Done by hand.)

[DennisD]

Hi Ed,

Beautiful job ! Despite the camera, the final format is certainly large ! I haven't completely loaded the full size file yet, (taking some time), but so far the image appears to be excellent and perfectly stitched.

Could you describe in more detail the camera / tripod setup (i.e. how carefully did you follow panoramic guidelines). Also more specifics on your processing workflow.

I assume 2exposures were taken, then you shifted camera to next position-total of 80 exposures ?
Was the orientation of the lens horizontal / vertical ? 4x10 layout ?
What was sequence of stitching and HDR ?
Anything else of interest would be great including any other processing info.

Thanks for sharing a very interesting project.

[Ed Richards]

Nikon D600, ASA 200, 85mm F1.8, f9.5, 0.7 sec and 6 sec, everything set to manual, of course. The camera is on my Gitzo video tripod, which has a leveling head built in. The actual tripod head is a pan/tilt head (rotates and tilts in one axis - it is my view camera head). That lets me level the camera independently of the head, so I can then rotate the head and everything stays level. it is an 8x5 vertical matrix, done strictly by eyeballing the overlap. The camera was set to lock the mirror and bracket, so each shoot took for four clicks - up mirror, shoot, up mirror, shoot, with the camera shifting the exposure for me. Very tedious and you need to stay alert or you will lose track and have to start over. The Nikon 85mm f1.8 has almost no distortion or vignetting, so I just loaded the raw files directly into PTGUI Pro. It auto aligns them. It will manage the exposure, but I had it output a 32bit HDR file, which I then tone mapped in Photomatrix. The master 16bit TIFF is about 2 gigs. I cropped and tuned it a bit in Lightroom 5. I should have shot at f11, the near pews could be sharper. The 85mm gives a unique perspective because it avoids what would otherwise be wide angle distortion if I had used a single exposure and very wide lens. I was in the choir loft which was high enough to let me shoot in the middle of the church. The final file has more resolution than a drum scanned 8x10, and I am not sure I could have managed the contrast as well with film. If I do this very often, I am getting a panorama tripod head with index points.

[Bill_1856]

Why? What is the point? Is there some final product you are planning which requires 95 megs? What is your final print size?

[DennisD]

The Nikon 85mm f1.8 has almost no distortion or vignetting, so I just loaded the raw files directly into PTGUI Pro. It auto aligns them. It will manage the exposure, but I had it output a 32bit HDR file, which I then tone mapped in Photomatrix.

Appreciate the detailed explanation, Ed.

If I understand correctly, PTGUI handled the stitching and the integration of both sets of exposures - the .7 sec and the 6 sec exposures of which there were 40 each for a combined total of 80 images. I thought PTGUI was primarily for stitching and was not aware that It would output an HDR file. Cool !

Thank you very much.

[Ed Richards]

Why? What is the point? Is there some final product you are planning which requires 95 megs? What is your final print size?

Dangerous question on this forum.:-) I doubt 5% of the folks shooting LF are making prints that need LF.

I used the 85mm for the perspective, that drove the number of images. The resolution allows crops for details that will still make good prints. The multiple exposures tame the dynamic range better than I can do with film. I have also stitched 4x5 to get better perspective, but when you start doing multiple exposure stitches with 4x5, you have ask if it is the right tool. Churches with stained glass are a challenge to shoot when you are traveling and don't have the option of waiting for the right light. I don't have the resources to add light, or the time, and it would require special permissions. Maybe even a generator.

[Jim Galli]

That's it! The 8X10 is officially dead. Anyone want this crap, come and get it.

[Ed Richards]

That's it! The 8X10 is officially dead. Anyone want this crap, come and get it.

It is, commercially. But that is not why you shoot it.:-) This is a particular imaging problem I have that has proved frustrating to solve with LF. It lends itself to this solution because it is completely static so I can use an imaging technique that takes 20+ minutes for an exposure. I am interested in solving it because I shoot for the images and prints, not the fun of the technology. But if I want to mess with perspective, esp. wide angle perspective, I will still use the 4x5. I will also use LF if I am doing an outdoor shot where clouds or other movement is an issue. If the camera fairy gave me a top end MF digital back and a 6x9 camera, I would dump LF because it would not make sense to use it instead for the images I shoot.

[polyglot]

You can still get the wideangle perspective, you just need to choose the appropriate projection in the final assembly. You've got what looks like cylindrical (or similar variation) here; if you choose rectilinear then you get the traditional wideangle look. And note that because the stitcher performs a spatial remapping of EVERY pixel, you can use any length lens you want for the source material and have the final result come out the same, geometrically. Choosing a longer objective lens just means taking more images and gives a higher output resolution for a given total angle of view.

This is arguably digital LF, though obviously the exposure is made piecemeal and then assembled. Assuming 40 exposures with an average of 60% area overlap (50% in each dimension, less the edges) implies a total exposure area somewhere between that of 4x5" and 5x7".

[bdkphoto]

It is, commercially. But that is not why you shoot it.:-) This is a particular imaging problem I have that has proved frustrating to solve with LF. It lends itself to this solution because it is completely static so I can use an imaging technique that takes 20+ minutes for an exposure. I am interested in solving it because I shoot for the images and prints, not the fun of the technology. But if I want to mess with perspective, esp. wide angle perspective, I will still use the 4x5. I will also use LF if I am doing an outdoor shot where clouds or other movement is an issue. If the camera fairy gave me a top end MF digital back and a 6x9 camera, I would dump LF because it would not make sense to use it instead for the images I shoot.

It seems like an awful lot of unneeded work for an interior like this. Something like a 5dmkII would give you a single file of 128MB in size, a 2 or 4 frame stitch (4 is total overkill IMO). No need for HDR either.

[Amedeus]

Nice work Ed, great example of a 2D stitch ...

I stitch a lot with MF digital back on Mamiya/Phase One and appreciate the time and effort to get the technology and the end result right. What's your final print size ?

[Ed Richards]

In my software, rectilinear doesn't change it much, but I understand what you are saying. In theory, the software could remap it any way you want. In practice, at least with the software I am using, it does not work out very well when you deviate much from the shooting perspective. (This may be a limitation of my understanding of the software - there are some complex configuration options that would likely help with what you are proposing.) As you say, the more interpolation it does, the lower the quality of the image output, and I am trying to preserve the hyperreal LF look. There is also a lot more correction for the wider lenses because all of them have pretty high distortion compared to LF lenses. The 85 is pretty much perfect so there is not the additional overhead of lens corrections. I could probably have done fewer shots if I had a calibrated pano head, but I was eyeballing in a dark church so I wanted to make sure I had a lot of overlap. Plus, the higher the overlap, the easier the fitting and the less processing of the images.

I am glad you mentioned digital LF, that is exactly how I look at it. I am working toward an LF sized negative, albeit an electronic negative. Think of it as an electronic alt-process. I think the effective negative is bigger than the actual area because I get better pixels than I would from scanning.


You can still get the wideangle perspective, you just need to choose the appropriate projection in the final assembly. You've got what looks like cylindrical (or similar variation) here; if you choose rectilinear then you get the traditional wideangle look. And note that because the stitcher performs a spatial remapping of EVERY pixel, you can use any length lens you want for the source material and have the final result come out the same, geometrically. Choosing a longer objective lens just means taking more images and gives a higher output resolution for a given total angle of view.

This is arguably digital LF, though obviously the exposure is made piecemeal and then assembled. Assuming 40 exposures with an average of 60% area overlap (50% in each dimension, less the edges) implies a total exposure area somewhere between that of 4x5" and 5x7".

[Ed Richards]

I should be able to do a print at 100 inches (2.5m) on the long side. I am unlikely to it with this image, unless the Church would want to have one. I am working on some images of the LSU football stadium that might be useful at this size for commercial use.


Nice work Ed, great example of a 2D stitch ...

I stitch a lot with MF digital back on Mamiya/Phase One and appreciate the time and effort to get the technology and the end result right. What's your final print size ?

[Daniel Stone]

It seems like an awful lot of unneeded work for an interior like this. Something like a 5dmkII would give you a single file of 128MB in size, a 2 or 4 frame stitch (4 is total overkill IMO). No need for HDR either.

Ed already explained his methods before, and the reason for doing them like he did:


Dangerous question on this forum.:-) I doubt 5% of the folks shooting LF are making prints that need LF.

I used the 85mm for the perspective, that drove the number of images. The resolution allows crops for details that will still make good prints. The multiple exposures tame the dynamic range better than I can do with film. I have also stitched 4x5 to get better perspective, but when you start doing multiple exposure stitches with 4x5, you have ask if it is the right tool. Churches with stained glass are a challenge to shoot when you are traveling and don't have the option of waiting for the right light. I don't have the resources to add light, or the time, and it would require special permissions. Maybe even a generator.


Interesting project Ed!
By chance, were you shooting tethered, say to a laptop running Lightroom(tethered) or Capture One? I've worked for a few architectural guys here in LA, and tethered capture is extremely handy(even if going to a laptop portably, shooting out on the street). It allows cataloging very easily, processing out of files quickly(albeit you can do it once home), and a much larger, clearer monitor to gauge exposure, etc. on.

Just wonderin :)

cheers!
Dan

[Ed Richards]

Re file size: The jpg is 95megs. The working file is 2 gigs of clean, sharp pixels. You do not get that with a couple of pops.

I did not shoot tethered. If I did this professionally, I certainly would. In this case it would have defeated my purpose, which was to see how much I could pair down the gear I carry and still get LF or better results. I have been wrestling with the problems of traveling with LF, as well as the issue of DR for church interiors. The toting gear issue is also why I am not that interested in a Gigapan solution. (Plus stories about their instability make me nervous - get a shaky image in the middle of your matrix and you are screwed, and unless you review all the images at the time, there is no way to know.)

[sanking]

The camera was set to lock the mirror and bracket, so each shoot took for four clicks - up mirror, shoot, up mirror, shoot, with the camera shifting the exposure for me. Very tedious and you need to stay alert or you will lose track and have to start over.

Ed,

Why did you up the mirror for every shot? When I do that kind of work I find it much easier to use Live View.

Sandy

[Jim Andrada]

Very nice. I use a Canon 5D (original) on a lightweight pano head with an 8mm fisheye lens for HDR spherical panoramas to import into Cinema 4D as HDR environments for computer generated models. 18 shots (3 each in 6 orientations) and a trip through PTGui and a bit of clean up of the bottom "pole" in Photoshop to get rid of the tripod legs and I'm there.

I'd be nuts to try this with my 8 x 10 Linhof or any film camera for that matter and for the purpose I don't need ultra high resolution - just trying to get reasonably realistic environmental reflections from the model.

I think it's simply a case of using the appropriate tool for the job at hand. I truly love working in LF but I'm certainly not blind to the advantages of digital. And if I had the $$$ I'd probably get a Phase One with a B&W back and still keep using my LF cameras as well.

[Kirk Gittings]

Good job Ed. Have you tried this for generating high quality b&w? I have. I worked on it to make personal b&w images possible when I was traveling for commercial work and only had my DSLR with me. It took me a long while and a ton of paper and ink to get to where I felt good about hanging my full digital ink prints next to my traditional silver b&w but I got there-a very different path with unique problems but doable.

[Ed Richards]

Kirk - it makes great black and white prints. That is my real interest, but I keep the intermediate color files just in case. I do not have your history - the last silver prints I made or had made were 30 years ago from 35mm film. But I did spend a LOT of money getting to where I could make a good digital print. Part of that was starting before the printers really got good, so I messed with RIPs and lots of other things, plus a lot of paper and ink, to get neutral prints and to learn how to print digitally. If the Epson 4900 and today's paper had been around 10 years ago, I could have spent the money on a new car instead.:-) What I am thinking about now is appropriate print size - if I keep to 11x14 or smaller, I cannot see any difference between a single exposure on the D600 and LF. If the image is graphically strong without fine detail, I can do a much bigger print before seeing any difference.

Sandy - as best as I can tell, the D600 drops the mirror, then pops the mirror back up, then takes the shot in live view. There maybe a setting to keep the mirror up all the time, but I have not found it. I was locking up the mirror with the first click, then waiting a couple of seconds before I took the exposure. I wanted to make sure the camera was settling down because I was in that shutter speed range where mirror slap matters. Except for battery life and heating the sensor, it would be nice if there is a way to just lock it in the live view and shoot without the mirror going down at all.

[paulr]

I've thought about combining stitching with exposure blending, but it's always seemed like way much work, and too many similar exposures to try to juggle. Do you feel like you have a manageable workflow for doing this? Would this be a method for unusual circumstances, or do you think you could go out and do a dozen images?

Also, if you're interested in tethering, there's a tool called CamRanger that everyone's raving about (I haven't tried it yet). Costs $300 and allows wireless camera control and live view from a laptop, smartphone, or tablet.

You should be able to take the lens off and fire off a pic in live view ... you'll see if the mirror stays put or not. On the d800, live view works like mirror lockup. It would be goofy (although very Nikon-like) if this weren't consistent from one model to the next.

[Ed Richards]

I've thought about combining stitching with exposure blending, but it's always seemed like way much work, and too many similar exposures to try to juggle. Do you feel like you have a manageable workflow for doing this? Would this be a method for unusual circumstances, or do you think you could go out and do a dozen images?.

It is workable, but you have to be careful. I cannot think of why I would want to do a dozen big stitches of a given subject, but if I had a reason to do so, it would just require patience. Small projects are easy - 4x4 is very easy and gives a great image if you do not also need to manage DR. You can stitch by hand if there is enough light and dramatically improve what you could get with a single pop. The key is that it is the only way to get a really high rez image with easy to carry equipment.

[sanking]

You should be able to take the lens off and fire off a pic in live view ... you'll see if the mirror stays put or not. On the d800, live view works like mirror lockup. It would be goofy (although very Nikon-like) if this weren't consistent from one model to the next.

Yes, it would be pretty odd that the Live View feature is so different on the D600 and D800. On the D800 the mirror stays up until the button to deactivate live view is pressed, or until the camera is switched off.

Sandy

[Ed Richards]

Sandy - product differentiation. :-)

[Daniel Stone]

Sandy - product differentiation. :-)


sells more accessories that way :p

[Drew Wiley]

So I guess this simply proves once again that given enough time a mouse can eat as much as an elephant?

[Ed Richards]

For those who are interested, this is St Andrew's Presbyterian Church (http://www.standrewstoronto.org/index.html), in Toronto.

[sanking]

You can still get the wideangle perspective, you just need to choose the appropriate projection in the final assembly. You've got what looks like cylindrical (or similar variation) here; if you choose rectilinear then you get the traditional wideangle look. And note that because the stitcher performs a spatial remapping of EVERY pixel, you can use any length lens you want for the source material and have the final result come out the same, geometrically. Choosing a longer objective lens just means taking more images and gives a higher output resolution for a given total angle of view.

This is arguably digital LF, though obviously the exposure is made piecemeal and then assembled. Assuming 40 exposures with an average of 60% area overlap (50% in each dimension, less the edges) implies a total exposure area somewhere between that of 4x5" and 5x7".

I am interested in your comments about perspective. Can you recommend a good reference on the process of choosing an appropriate projection in the final assembly?

Sandy

[polyglot]

I am interested in your comments about perspective. Can you recommend a good reference on the process of choosing an appropriate projection in the final assembly?

Assuming you're doing this for art not science, I would suggest just previewing them all to see which ones best suit your vision (what's "appropriate" is all up to you) for each scene. To be more formal, though, each is a mapping from 3D scene space to the 2D image space and each preserves different metrics. For example:
- rectilinear preserves all straight lines. Magnification is constant on a plane perpendicular to the view direction, but magnification increases towards the frame edges for things at constant distance from the entrance pupil. This is what 99% of physical lenses do. FOV must be <180 degrees.
- cylindrical (http://mathworld.wolfram.com/CylindricalProjection.html) preserves vertical lines as straight and the equator also, but all other horizontal lines curve. Circles of latitude around the camera become horizontal straight lines. Horizontal FOV can be up to 360 degrees.
- equirectangular (http://en.wikipedia.org/wiki/Equirectangular_projection) is similar to cylindrical, preserves meridians as vertical lines but has a different treatment of distortion at the poles
- Mercator (http://en.wikipedia.org/wiki/Mercator_projection) preserves linear scale at all view angles, which means massive area distortions
- Fisheye (http://en.wikipedia.org/wiki/Fisheye_lens) (there are variations here) generally preserves a relationship between scene-space angle and image space distance.

See also Wikipedia on map projections (http://en.wikipedia.org/wiki/Map_projection). Think of the camera as being at the centre of the earth, the projection is how you map the surface of the earth (scene space) onto the film plane.

If you want the "I bought a SA XL" look, choose rectilinear and make sure you have huge coverage in your shots out to the corners of the field of view. Using a DSLR with a stupid-wide lens on it, take a preview snapshot and make sure that your stitch-source images cover everything in the snapshot. Note that a pan-tilt head (azimuth/elevation) effectively implements the cylindrical/equirectangular projections (they differ at the poles) therefore merely taking an array of N*M photos with a pan/tllt head at fixed intervals will NOT give you proper coverage of a wide rectilinear image. You need to go to greater elevations at the azimuth extremes to fill in the corners - you'll see what I mean when you do it wrong, the corners of the image will be rounded/missing in the preview if you took a simple grid of photos with pan/tilt.

Of course the drama in such wide shots is to have a big magnification difference between near/far elements, i.e. dramatic perspective. Getting nearby objects to stitch cleanly requires very careful lens motion while shooting, usually with a nodal head. Getting a stitch with no near elements is far easier, but (IMHO) lacks the drama that comes with wideangles and is therefore a little (artistically) pointless.

[invisibleflash]

Ed, pretty pix. but I could never do it. Too many exposures to keep track of for me.

[Paul H]

Some good information there Ed. Have you considered using something like the GigaPan rig?

I noticed in the latest versions of Autopano Pro, there is an option to compress the edges of rectilinear projections, so you have some control over the "stretching" or increased magnification towards the edges of the frames

[Ed Richards]

I have thought about the Gigapan system. From what I have read, it has some stability issues with FF DSLR size cameras, esp. with longer lenses. Since I often shoot in low light, where camera movement is big problem, that put me off. It is also a fairly big piece of gear with special batteries. My goal with this project is figure out the easiest to carry and pack gear that will give me LF level quality images. I may add a pano head to make life easier, but still have a small pack of gear. Gigaplan would add a good sized case to my camera gear.

PTGui Pro is very flexible, I just do not know the program very well yet.

[Ed Richards]

A wider shot. This was done with the 85mm and 90 images, no HDR, f 11. You can see the wide angle effect once I have extended the canvas. (The choir loft rail in the front of the image is straight.) This is a cylindrical projection.

This was a failure - two shots, in line, lower part of the altar and the floor below that one, had camera movement. Harder to see in this small image, but ruined the picture. My error - there is a learning curve on the Nodal Ninja pan head. I did not tighten it enough, and my remote release was not working.

http://www.epr-art.com/working/no-church.jpg

[AlexGard]

I have not read the majority of posts in this thread but thought I would throw in some thoughts.
When I was using a DSLR the majority of stuff I did was stitched images using either a 50mm 1.2 L or 85mm 1.2 LII lens. Primarily I was using the wider apertures to achieve a dreamy "bokehrama" effect (look up "the brenizer method" if it hasn't already been mentioned.. capable of stunning results. unfortunately I am on a blocked internet system so can't link to any of my flickr images)

I found this to be desirable over using a wider lens (my widest being 24mm on FF camera) as for the most part you could avoid unsightly lens distortion in the majority of the image except for where the foreground is incredibly close to the camera like the bannister in the above picture.

the bigger benefit was that you have incredibly high resolution, even if you desire a more 'standard' sized print... the sharpness and detail is mindblowing, especially with great optics like 50 & 85 primes wide open.

I too was using the "nodal ninja" with an rd-16 rotating head and a remote shutter release so the camera wasn't being knocked during exposure

the beauty of stitching was that I was able to get a couple of really large prints made up of absolutely incredible resolution and clarity, wicked sharpness (even the professional printers commented on how amazing the detail was). this also lets you make very interesting 'micro landscapes' of a smaller subject matter. Say for instance you drop the camera to the ground and open the lens wide, take a stitched panorama of a log or grassy/mossy scene that is not far from the camera. stitched together these almost have a macro look to them, and the depth of field control creates a very unique look.

I loved doing this and got some great results out of it and is definitely a cool way to do landscapes.

in my opinion the stitching is much more effective with prime lenses like 50 & 85. once they were calibrated to the NN it's the only way I was shooting. the 24mm only came out when I was doing moving subjects