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Finally concede that I need a nodal slide (and 360 virtual tours)

Ben Rubinstein

pro member
Huge project on at the moment. Working for a youth college taking endangered youth, mostly from broken homes, drug backgrounds, etc and helping them find themselves and a way in life.

The college recently bought up 5 huge buildings in Jerusalem, the buildings are old, from 120-400 years old with walls thicker than the length of your arm and a charm and beauty which has been utterly inspiring. Added to that the college have serious financial backing which they have used to make sure that everything from the hallways of the dormitories through to the eating halls and study halls look incredible. I couldn't believe the dining room with chandeliers, napkins in every place, food served to the table, etc. Wasn't like that in my college days! :)

They want me to shoot 360 degree virtual tours. I'd never done them but having done a test run in my lounge and knowing that I have the software included with Autopano I was sure it would be easy.

Oh no it ain't! Firstly I'd never bothered with all this nodal point nonsense. Why should I when Autopano is so good that I've never needed it? Um, this 'nonsense' is now suddenly very very important. Rotating a 16mm lens with multiple level stitches and I've been fighting with autopano all day to get a good stitch. It's working with both architecture and very very close up walls, chairs, objects etc where the magic runs out and there is just a limit to what it can fix.

An 8mm fisheye to give me a full 180 degree view might solve the problem, you don't need that much resolution anyway for a web sized thingy however I've discovered that my attempts to do multi level without a nodal slide are almost impossible, they just won't stitch when doing 360 in a small room full of stuff. Not without too many problems. On the other hand how do you use a tripod with a lens like that? Heck how do you keep your feet out of the frame even?

Or I could get a full two axis nodal slide rig and I've been sucessfully avoiding that particular pain in the neck for 3 years now.

Oh well, not that many more rooms to do, managed to force 8 'tours' to stitch albeit only 360X100, it will have to do, I gave them a charity price.

On the other hand added to the virtual tours I'm doing a lot of regular non pano shooting, some incredible stuff in these old buildings, as I said to a friend, I'm being paid to shoot my project!

Here is the head of the youth section marking papers in his office which is a piece of history in its own right, incredible room, I could sit there all day among 4 walls floor to ceiling with decade old books and silver artifacts...

r'yaakovhillel.jpg

Difficult shot to do, the room is shot with flash along the same axis as the lamp but kept very low to just bring enough detail into this dimly lit room which actually looked as it does in the photo.
 

Asher Kelman

OPF Owner/Editor-in-Chief
Ben,

What a wonderful project. Go to Kolor.com. Autopano Giga is what you need. The 8mm Sigma is perfect. You need just 3 or 4 shots and it will stitch seamlessly like magic. Amazingly, this lens is very sharp and so easy to use. It will be a revelation. They also have everything you need for a virtual tour! PM me your address and I'll write to see if we can get you the software, or at least a discount for the educational use. Without any promise, I'll look into a lens too. That is a long shot, but I'll try!

Asher
 

Ben Rubinstein

pro member
Ben,

What a wonderful project. Go to Kolor.com. Autopano Giga is what you need. The 8mm Sigma is perfect. You need just 3 or 4 shots and it will stitch seamlessly like magic. Amazingly, this lens is very sharp and so easy to use. It will be a revelation. They also have everything you need for a virtual tour! PM me your address and I'll write to see if we can get you the software, or at least a discount for the educational use. Without any promise, I'll look into a lens too. That is a long shot, but I'll try!

Asher

I have Giga thanks Asher, it's what I've been using and coming up short with on making the initial stitch. Autopano tour is very basic but perfectly comptent. I realise the sigma is the answer (I was thinking of a peleng with adapter but same difference) but unless I take this up as a career choice I'm not sure it's worth the investment! I'll be finished this project my Wednesday or so, been shooting it all week. I'll post up pics when I get a chance together with some of the tours.

Question though for those using a fisheye in low light, how do you keep the tripod legs out of the frame?
 

Asher Kelman

OPF Owner/Editor-in-Chief
I have Giga thanks Asher, it's what I've been using and coming up short with on making the initial stitch. Autopano tour is very basic but perfectly comptent. I realise the sigma is the answer (I was thinking of a peleng with adapter but same difference) but unless I take this up as a career choice I'm not sure it's worth the investment! I'll be finished this project my Wednesday or so, been shooting it all week. I'll post up pics when I get a chance together with some of the tours.

Question though for those using a fisheye in low light, how do you keep the tripod legs out of the frame?

Rent the lens! You'll need it foe just 1-2 days as everything will go very very fast!

Tilt the lens up a little. I think the suggestion is 5 degrees and then take one shot of the ground with another lens to be inserted later. Having the legs not too wide and the center stem raised helps. Search here on OPF as Bart and Valentin have shared this info before.

Asher
 

Ben Rubinstein

pro member
Spent 4 hours today on one really troublesome pano, just couldn't get it done, had already called the adminstrator to tell him that the room needed to be free on sunday for a reshoot. Just on a whim tried it in PTGUI, did it first time perfect! I'm a happy boy!

I think that anyone serious about pano should have both autopano and ptgui in their stable, this is the 2nd time PTGUI has saved my bacon..
 

Asher Kelman

OPF Owner/Editor-in-Chief
PTGUI has saved my bacon..

Odd metaphor for that location!

What's nice is that PTGUI can open Pano files.

With the 8mm fisheye you will find that stitching is a matter of a minute and it either works perfectly or not. So far, all my stitching of 2-3 shots have been hand held. So with a tripod your success will be 100%.

Asher
 

Ben Rubinstein

pro member
I spoke rather too soon, the image was too far gone even for ptgui but it got it within 5 mins work with the warp tool and that's good enough, looks great actually! Going to try out my other 360 pano's with ptgui tomorrow, see how they look compared to autopano.
 
Question though for those using a fisheye in low light, how do you keep the tripod legs out of the frame?

Hi Ben,

When you take multiple shots around, and use a competent stitcher/blender application (if necessary helped by using alpha channel masked transparency TIFFs), the blending engine will automatically remove most of the tripod legs. The only part that then remains is the camera base, which can be either overlaid with a logo, or cloned out with content aware fill, or with a separate "nadir" shot. When you plan, if possible, your tripod position over a rather featureless or repetitive part of the floor, then it won't be hard to do. A great help to me is a program like Pano2VR, its "patch tool" allows to export the nadir area, edit it in Photoshop, and read it back into the 360x180 degree VR panoshot and save the adjusted shot.

My shooting method may be a bit more elaborate than some others use, but I take shots at 8 positions (0, 45, 90, 135, 180, 225, 270, 315 degrees relative rotation), with a 15mm full frame fisheye. The reason is that I want close to 50% overlap between frames, for 2 reasons.
The first reason is for having enough control points in the overlap, and the second reason is for exposure and color balance blending between neigboring shots (because I like natural light scenes).

Cheers,
Bart
 

Valentin Arfire

New member
hi Ben
it's great to see you immerse into 360 degree panoramas :) I am sure the "panoramic movement" will gain much

please let me know if I can help you in any way

you can stitch multi-row panoramas made with any lenses - even rectilinear - just always keep in mind that npp errors will alterate the position and the geometry of things around; besides that if at the same time you can see over the corner of some obstacles they will definitely get distorted and the panorama will suffer

another lense (I don't have but serious panographers have recommended is the 8 mm Samyang)

the near future - April I think - will bring a Canon 8-15 mm
 

Ben Rubinstein

pro member
Hi,

The problem seems to have been having both very very near and quite far away objects in the same frame when rotating not using the nodal point. That is where both autopano and ptgui seem to give up. Not been a problem with my personal project outdoors, I'm not shooting anything that close up but indoors in tight quarters it's a very real issue. Of course the real solution seems to be the 8mm fisheye but as mentioned I'm doing this as a one off at present unless I get more interest in which case it will be worth the purchase.
 

Asher Kelman

OPF Owner/Editor-in-Chief
Plumb Line for getting rotation point fixed for Panos/

Hi,

The problem seems to have been having both very very near and quite far away objects in the same frame when rotating not using the nodal point. That is where both autopano and ptgui seem to give up. Not been a problem with my personal project outdoors, I'm not shooting anything that close up but indoors in tight quarters it's a very real issue. Of course the real solution seems to be the 8mm fisheye but as mentioned I'm doing this as a one off at present unless I get more interest in which case it will be worth the purchase.
Ben,

Can you rent? There should be rentals in Jerusalem. If not, Here's an alternative.

Get a plumb line. It's a few dollars. Set up your tripod and focus on the first frame on the left. Set up the string so that it's fixed above and align the string so it's in front of the lens and centered. Put and ink mark on the string at the vertical center of the lens. Move the string out of the way but don't move the attachment above. Take the first frame. Now move the tripod so that the lens is still centered on the ink mark but pointing to the next section of the room to the right. Proceeding that way, you can do the whole room. For the ceiling you need to drop the tripod but point the lens up so once again the ink mark is centered.

This will allow you to stitch adequately. There will be a slight mismatch perhaps, but when you render the pano, choose out put as layers. That's critical. Then in photoshop you can replace any sections of mismatch. Sometimes I will take the nearest frame that matches to what I would need to repair any defect, duplicate it and then "select all" and "edit-transform" and adjust it perfectly to fit in with the master-stiched-layer by "skew", "warp" or whatever tool works best. If you like it, accept or else start again with another transform. At the worst you might have 2-5 corners to repair - not a big deal for a one off!

If you set up your tripod exactly centered by one wall or corner, then sometimes you can flip copy sections of the room and flip horizontally for repair. Sometimes it's a perfect rescue in one simple move. Then blend the images using a mask and a soft black brush to get the rest of the master image to appear.

Hope this helps. It's really simple, just slow!

Asher
 

Doug Kerr

Well-known member
Hi, Asher,

Set up the string so that it's fixed above and align the string so it's in front of the lens and centered. Put and ink mark on the string at the vertical center of the lens. Move the string out of the way but don't move the attachment above. Take the first frame. Now move the tripod so that the lens is still centered on the ink mark but pointing to the next section of the room to the right.
I'm confused. That procedure seems to make the string (its location now seemingly fixed) the pivot point - not anywhere near the entrance pupil.

Is there something about this particular kind of work that does not make that relevant? Or have I misunderstood the manipulation you are describing?

Best regards,

Doug
 

Asher Kelman

OPF Owner/Editor-in-Chief
Hi, Asher,


I'm confused. That procedure seems to make the string (its location now seemingly fixed) the pivot point - not anywhere near the entrance pupil.

You are absolutely right on your misgivings. I have a correction for the entrance pupil but it requires a macro stage and that's to costly and not needed. In practice, Autopano Giga will do well if there's good overlap and then one corrects mismatches my repair, as specified above.

Try it, it works!

Asher
 

Asher Kelman

OPF Owner/Editor-in-Chief
Ben,

Send me your address, you will shortly receive a Pano head that a MFR has kindly donated, I just pay the shipping. That will give you a means to do this project with applomb and without the plum line, LOL!

Asher
 
Hi,

The problem seems to have been having both very very near and quite far away objects in the same frame when rotating not using the nodal point. That is where both autopano and ptgui seem to give up. Not been a problem with my personal project outdoors, I'm not shooting anything that close up but indoors in tight quarters it's a very real issue. Of course the real solution seems to be the 8mm fisheye but as mentioned I'm doing this as a one off at present unless I get more interest in which case it will be worth the purchase.

Hi Ben,

As usual, the real solution is doing it right from the start ;-) Pano stitching, especially with close foreground features, will be trouble free with a correction for the no-parallax point (entrance pupil of the lens). Relying on the blending engine to cover up one's mistakes often works, except for when you most need it, it's Murphy's law.

One can stitch a 360x180 degree VR scene with any lens, not just one with a fish-eye projection. It just take many more tiles to stitch, and you'll potentially have less DOF than you wish for, but the resolution (=potential to zoom in) will be superior with longer focal lengths. Your 16mm is well suited for this task, you just need to correct for the no-parallax point of rotation.

If you need to stitch multiple rows to cover the vertical FOV, you may want to first do each row individually if you don't have a proper 3D VR head on your tripod.

Renting a fisheye lens may be the fastest solution for a limited number of sessions, but you'll want to spend some money on a 3D VR head if you don't want to be stuck behind the computer trying to fix things. I know that spending money has it's limits, so if you have the time and need some advice on how to not spend too much figuring out things, just let me know.

Cheers,
Bart
 

Ben Rubinstein

pro member
Wooow, Wooow!

Firstly Asher who is this saint 'MFR'?

You guys are incredible, firstly Valentin offers to stitch for me then this, these wonderful kids are in your debt. Here's another couple of pics, the first building I was working in and a picture of one of the kids in this building. He was really shy when I told him that I wanted him to just carry on and ignore me, that picture is going to be added to my Jerusalem project!

b1.jpg



b2.jpg
 

Ben Rubinstein

pro member
Hi Ben,

As usual, the real solution is doing it right from the start ;-) Pano stitching, especially with close foreground features, will be trouble free with a correction for the no-parallax point (entrance pupil of the lens). Relying on the blending engine to cover up one's mistakes often works, except for when you most need it, it's Murphy's law.

One can stitch a 360x180 degree VR scene with any lens, not just one with a fish-eye projection. It just take many more tiles to stitch, and you'll potentially have less DOF than you wish for, but the resolution (=potential to zoom in) will be superior with longer focal lengths. Your 16mm is well suited for this task, you just need to correct for the no-parallax point of rotation.

If you need to stitch multiple rows to cover the vertical FOV, you may want to first do each row individually if you don't have a proper 3D VR head on your tripod.

Renting a fisheye lens may be the fastest solution for a limited number of sessions, but you'll want to spend some money on a 3D VR head if you don't want to be stuck behind the computer trying to fix things. I know that spending money has it's limits, so if you have the time and need some advice on how to not spend too much figuring out things, just let me know.

Cheers,
Bart

Renting in Jerusalem doesn't exist, tried to start up a rental shop about a year ago but the idea needed far more funding than me and my partner had at the time. Oh well.

Point is though that the fisheye would seem to be the best solution given how little resolution is needed for web virtual tours (relatively). I've managed to avoid the dual axis nodal slide system for my own personal system to the extent that I bought a large format camera to obtain the required resolution 3 years ago before discovering that for the work I was doing I could make multi level stitches without the whole dual axis rig.

Again, I'm finished this project this week, Wednesday the latest for the pano work, only a couple more rooms to do with 360 pano's...
 

Doug Kerr

Well-known member
Hi, Asher,
You are absolutely right on your misgivings. I have a correction for the entrance pupil but it requires a macro stage and that's to costly and not needed. In practice, Autopano Giga will do well if there's good overlap and then one corrects mismatches by repair, as specified above.
Oh, I see - the plumb line is immediately in front of the lens. (I had envisioned it as a foot or so away - you didn't say either way.)

So it's probably closer to the entrance pupil than, say, the tripod head azimuth axis is.

Very clever.

Best regards,

Doug
 

Ben Rubinstein

pro member
I finally understand your idea Asher, I'm a bit slow, as Doug says, very ingenious!

How does one find the entrance pupil for a lens at a give focal length? I never once understood the tutorials for finding it (rather intimidated me) but you people really know what you are talking about. What's the trick?
 
Ben, give Moshe Caine a call

I understand you've got the project wrapped up, or nearly so. But you might want to show what you've got to Moshe Caine, who teaches this stuff at Bezalel and heads a small department at Hadassah College. He's a friend and very helpful advisor, so use my name. He does multimedia installations for the Bible Lands Museum and commercial clients. If he is in the mood to do a post-audit and critique with you, you can learn a lot that will make the next project like this easier and maybe even stronger. Plus, he'll be interested in your pictures.

I don't have his phone number handy, but Google picks him up.

good luck,

scott

PS -- and where is this lovely old school?
 
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Doug Kerr

Well-known member
Hi, Ben,

I finally understand your idea Asher, I'm a bit slow, as Doug says, very ingenious!

How does one find the entrance pupil for a lens at a give focal length? I never once understood the tutorials for finding it (rather intimidated me) but you people really know what you are talking about. What's the trick?

There are two practical ways to locate the entrance pupil of a lens (and indeed for zoom lenses its position may depend on the focal length setting).

The first technique just looks for the actual behavior we are trying to attain. Basically, with the camera on some appropriate type of adjustable mount, we initially position the camera so that what we estimate might be the entrance pupil is located over the vertical pivot.

We train the camera on some scene having both near and distant objects. While observing through the viewfinder (or Live View is even better) we note the alignment of a near and far object (for example, where a near lamppost seems to fall on the front of a distant building), preferably with them at one side of the frame.

Then we swing the camera on the panoramic pivot in the direction that moves these objects toward the other side of the frame, noting if the relative alignment of these two objects shifts.

If it does, we have not pivoted about the entrance pupil, so we shift the camera mounting and try again.

The rule is that if we swing the camera to the right (so the objects shift left in the finder), and the near object seems to shift to the right compared to the far object, then the pivot point is now beyond the entrance pupil (closer to the scene), so the camera is two far back on the mount. We must the move the camera forward and test again.

In the second technique we just see where the entrance pupil is. If we look into the front of the lens, and "see" the aperture diaphragm, we don't see it where it actually is (inside the lens), but (because of the refractive effect of the lens elements in front of it) we see it in a different place.

What we seem to see is by definition the entrance pupil, and where it seems to be is where the entrance pupil actually is.

So we just estimate where it is by observing it!

We may have to use the DoF preview button, or fire a test shot, to stop down the aperture to help us identify which circle we see is in fact the aperture; we might even need to estimate its apparent location with the aperture stopped down using DoF preview.

Best regards,

Doug
 

Alain Briot

pro member
I do all my panoramas with a ballhead, by simply pointing the lens right and left. No problems. The software takes care of all parallax and other issues. And, I'm concerned with quality, obviously.
 

Asher Kelman

OPF Owner/Editor-in-Chief
I do all my panoramas with a ballhead, by simply pointing the lens right and left. No problems. The software takes care of all parallax and other issues. And, I'm concerned with quality, obviously.

Of course, Alain,

Most of the time you are doing landscapes! For indoor work with corners, posts, chair legs and so forth, parallax becomes a severe issue. I am able to correct almost any mismatch in photoshop if I have the stitching output in layers. However, that takes too much time when there are 30 such interiors and no money to cover the time!

Having a setup makes everything simply fall into place. For interior dynamic views of rooms and halls, or virtual tours, using an 8mm lens, the process is just a few minutes per room!

Handheld, there could be 1-4 hours of corrections afterwards to make things perfect!

Asher
 

Alain Briot

pro member
Actually I only do landscapes. And other people on this forum also do landscapes, lets not forget it! But even then I have no parallax problems even though some elements are only a couple feet from my lens. Software is better than many believe at correcting these problems. The only issue I can't fix is extreme lens distortions when turning the camera from right to left when using a wide angle. Software is "lost" then and can't do the stitch. Maybe in the future it will be able to?
 

Ben Rubinstein

pro member
They didn't let me do any 360's today, deferred till tomorrow, these are some of my favorite from todays work in the college and it's incredibly beautiful campus.

csd2.jpg


csd1.jpg


csd3.jpg


Csd5.jpg



As I've said before, it's incredible to be paid to shoot the kind of stuff you were doing anyway for your own personal project...
 

Alain Briot

pro member
"It's incredible to be paid to shoot the kind of stuff you were doing anyway for your own personal project..."

I wouldn't have it any other way ;-) !
 

Asher Kelman

OPF Owner/Editor-in-Chief
"It's incredible to be paid to shoot the kind of stuff you were doing anyway for your own personal project..."

I wouldn't have it any other way ;-) !
Alain,

As you know, advocate and teach, marketing is the one of the important considerations in linking one's own passion in photography to putting bread on the table, a car in the garage and money in the bank!

Ben,

In today's challenging times, with every 5th person, it seems waving a DSLR, that opportunities for professional photographers get less as folk settle for "good enough" for weddings and even photojournalism. You are one of those photographers who has borne the brunt of such overflowing mediocrity!

So where do panos come in? I believe that if one has indeed a passion for seeing the things one loves in a new way and panoramas hits such a sweet spot, this is something we should consider mastering. Klaus Esser, for example, has developed a business model centered on pano and virtual tours. So this is a path folk might consider in their total offerings.

Asher
 
Actually I only do landscapes. And other people on this forum also do landscapes, lets not forget it! But even then I have no parallax problems even though some elements are only a couple feet from my lens. Software is better than many believe at correcting these problems.

Hi Alain,

Sure, a good blending engine in a stitcher, or manual blending, can hide a lot of issues. The trouble with architecture is that there are too many give-away clues that there have been manipulations. With fewer give-aways, one can choose to render e.g. the foreground without parallax, but then the background will have parallax, and vice versa (or somewhere in between). However, especially with 360x180 degree shots, there will be lots of tiles to adjust when using longer focal lengths. That is not efficient and may even prove impossible depending on scene content. What's more, it can be avoided by using proper technique which will significantly cut back on postprocessing time.

Proper technique will also open up the possibilities of focus stacking, especially useful when using longer focal lengths for increased resolution stitching.

The only issue I can't fix is extreme lens distortions when turning the camera from right to left when using a wide angle. Software is "lost" then and can't do the stitch. Maybe in the future it will be able to?

No, not if you need (like in most architecture shots) to use a rectilinear projection (just like on flat film or sensors), it's inescapable physics. You can use a different projection method, but then straight lines will no longer be represented as straight lines (usually a disaster in architecture). With stitches of landscapes, one can often get away with alternative projections, e.g. cylindrical will often do just fine. For other scenes on may be able to use anamorphic distortion to mitigate the effect of a simulated extreme wide angle lens.

Cheers,
Bart
 
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