Stitching Success and Failure

[ColSebastianMoran]

As an exercise, trying to make a clean image of this building. No room to get very far back from the building facade, so this is make with a 28mm equiv lens, held in landscape mode (just wide enough for the base of the building) and a sequence of shots going upwards.

Here's a successful stitch assembled from four exposures.

Manual exposure, same for all shots. Nikon Coolpix A. Processed in Lightroom with lens profile corrections, then exported to PTGui, the result back to Lightroom to correct keystoning and final adjustments. This has rendered the building much taller than real life.

 

[ColSebastianMoran]

The net result is the equivalent of a very wide lens.

I think the Coolpix A, with Lightroom's len profile adjustments, has done a very good job.

 

[ColSebastianMoran]

Here's another try, this time made from only two exposures. There was enough overlap, theoretically this should have worked. Same process, lens corrections in Lightroom, export, PTGui, result back into Lightroom for final adjustments.

But it did not work. Interesting distortions.

 

[bobbyrab]

Have you tried Lightroom's stitch option, I've found it to be absolutely amazing, I've just stitched a group of 200 people from 5 separate full size Canon 5d mark iii frames, and it's seamless.

 

[retinax]

Looks like you accidentally selected a different projection in your stitching software, or it somehow defaulted to a different one. There are different ways, none of which is inherently more correct than another, to project scenes on flat media. Think of the differences between the images that a rectilinear wide, a fish-eye and a swing-lens camera give...

 

[ColSebastianMoran]

Have you tried Lightroom's stitch option, I've found it to be absolutely amazing, I've just stitched a group of 200 people from 5 separate full size Canon 5d mark iii frames, and it's seamless.

Interesting. Will try it.

 

[ColSebastianMoran]

Have you tried Lightroom's stitch option, I've found it to be absolutely amazing, I've just stitched a group of 200 people from 5 separate full size Canon 5d mark iii frames, and it's seamless.

Thanks, I hadn't known of this LR item. But, very interesting, the geometry is very different from the projection by PTGui. Lightroom has squashed my building down! PTGui left, Lightroom right. Truth is probably somewhere in the middle. EDIT: Truth is closer to the Lightroom rendering. I believe removing the keystoning in Lightroom has exaggerated the height of the building.

This merge is quite extreme, I'm looking up at the top of the building at an extreme angle.

 

[bobbyrab]

Oh not good, did you try out the other options within LR, I think it defaults to spherical

 

[bobbyrab]

I've always used it for landscapes, maybe it's not set up for verticals

 

[Shac]

I use the Photoshop option (in Bridge) - seems to work fine - but will try the LR version next time just to see.

 

[Henry]

I've always used it for landscapes, maybe it's not set up for verticals

I have used it for vertical images like the ones in this thread a few times. Usually with some trial and error it can be made to produce proper results, though often additional perspective correction is required.

I think Lightroom likes to default to weird projections, or it tends to pick bad ones when set to auto at least.

 

[ColSebastianMoran]

Oh not good, did you try out the other options within LR, I think it defaults to spherical

Yes, this is the "Perspective" option in Lightroom which I believe is "rectilinear" in other programs.

Most of my Panos are extreme wide; I use cylindrical most of the time.

 

[ColSebastianMoran]

This is about the barrel-distorted building in #3 above...

Looks like you accidentally selected a different projection in your stitching software, or it somehow defaulted to a different one. There are different ways, none of which is inherently more correct than another, to project scenes on flat media. Think of the differences between the images that a rectilinear wide, a fish-eye and a swing-lens camera give...

Yes, they are quite different. No, this was set for rectilinear. Interestingly, I tried it again with better results. This was from two shots, hand-held. I had shifted the light pole in lower-right of the frame; in the distorted image, PTGui tried to keep the light pole together. On a second try, and a third with masking, the merge is quite good from two shots.

Lesson: Watch what the program is doing, make adjustments (e.g. masking, setting control points).

FWIW, the PTGui program is excellent, has more controls of the merge process. Lightroom is quite good, fewer controls.

 

[ColSebastianMoran]

Looking at reference images of the building, I think the Lightroom proportions ("squashed") are better than the first posted (tall) image.

Lesson: Watch proportions when distorting and merging images.

 

[ColSebastianMoran]

Exploring the controls in PTGui a bit more, I am able to correct the perspective distortion in PTGui, delivering an image in good proportion with only minimal perspective distortion to Lightroom. I believe this image shows the building in correct proportion.

 

[ColSebastianMoran]

Here's my revised recipe:
- Raw conversion, lens profile corrections, basic color, etc. in Lightroom
- Export full size unsharpened images as jpg
- Load these in PTGui, hit Align Images; this brings up the Panorama Edit window
- Use center point tool to pick the center point. In this case, it's near the bottom of the building. Adjust center point to give desired perspective (minimal keystoning in this case).
- In the same window, change the Field of View (vertical in this case) to show the desired area.
- Create Panorama in PTGui
- Bring merged image back into Lightroom for crop and final adjustments

The PTGui Pano Edit window looks like this:

 

[charjohncarter]

I use Microsoft ICE which is a free program, and they have improved it over the years. you might download it and try. The newest version has lots of digital corrections for problems like you have had.

 

[retinax]

This is about the barrel-distorted building in #3 above...



Yes, they are quite different. No, this was set for rectilinear. Interestingly, I tried it again with better results. This was from two shots, hand-held. I had shifted the light pole in lower-right of the frame; in the distorted image, PTGui tried to keep the light pole together. On a second try, and a third with masking, the merge is quite good from two shots.

Lesson: Watch what the program is doing, make adjustments (e.g. masking, setting control points).

FWIW, the PTGui program is excellent, has more controls of the merge process. Lightroom is quite good, fewer controls.

Interesting, I wasn't aware that positioning issues could cause funny distortions after merging, certainly something to keep in mind.
Your final result looks very good! But it also shows the limitations of this technique: at the top of the building, the protrusions on the building still clearly show the perspective from which the picture was taken, while the shape of the building doesn't. This has greatly discouraged me from such extreme perspective alterations after I discovered it in my own attempts... it only really works for flat subjects. OTOH one could embrace it to make Escheresque pictures.

 

[farlymac]

Three frames is usually my absolute minimum I'll take when doing any panoramic work, but I have gotten by with two sometimes. And the cylindrical projection works best for me in PSE10. But the distortion control feature is a bit dodgy, so I leave that alone until I can get better software, or go with the cloud versions of PS or LR.

Here are some examples https://flic.kr/s/aHsjs46ohy

PF

 

[ColSebastianMoran]

Your final result looks very good! But it also shows the limitations of this technique: at the top of the building, the protrusions on the building still clearly show the perspective from which the picture was taken, while the shape of the building doesn't. ... snip ...

Thanks. And, yes, I am looking upwards at a 60 degree angle to the top of the building. Perspective shows a bit at the top and in the left-hand portion of the building which is set back from the front. Also, street-lamp vs. building shows perspective.