Stitching Flat Images, my nightmare

[Luis Argerich]

Introduction:

I'm quite seasoned in panorama stitching using diffrent tools, I've used PtGui, PtAssembler, Hugin and others to assemple all kinds of different panos, I'm confortable with refining control points, using vertical and horizontal control points, etc.

Lately I've been trying to assemble some panoramas where the camera is moved as a scanner to capture a flat image, can call them orthonormal panoramas, flat stitching, mosaics, whatever.
I understand it is important to have everything at the same distance to the camera to avoid parallax errors.

I've tried with a train, with houses on a block and lately with some aerial pictures taken from exactly the same height. So far all the "automated" tries have failed, including PtGUI, Hugin, PanaVue Image Assembler and others.

So question #1:
Does anyone have a workflow that is good to work with automated assembly of this images? Ptgui, Hugin? Others?

And question #2:
If there is no simple or acceptable way to automate the stitching then I'll be forced to manual-stitch, I know soem photographers are very good at manual stitching so I need to know how to start, any book? tutorial? pointers to start with manual stitching?

Thanks for any help you can give me!
Luigi

[JeffKohn]

The only flat stitching I've done is with images that were taken using lens shift, which is not quite the same thing as what you're doing. But Photoshop's Photomerge works very well with the "Reposition Images" option selected, which avoids any of the projections or interpolations that normally occur with pano stitching. PGui/Autopano/etc are not suited to this type of stitching since they always use a projection.

Assuming a flat subject where there is no parallax, Photoshop shouldn't have any problems stitching the images you describe. If it fails, I would guess it's because the camera wasn't "shifted" parallel to the subject, or you didn't have enough overlap.

[bradleygibson]

I second Jeff's suggestion to try Photoshop's PhotoMerge.  I don't know when the feature appeared, but the version beginning with CS3 (or later) is the one you want to try.

[Panopeeper]

Luigi,

I think there are two possible approaches:

1. declare a very narrow FOV, like less than 5°. The effect is as if you had made the shots from very far away,

2. try to position the frames with the horizontal and vertical shift parameters of the stitcher. I guess this requires more work.

[elf]

I've tried with a train, with houses on a block and lately with some aerial pictures taken from exactly the same height. So far all the "automated" tries have failed, including PtGUI, Hugin, PanaVue Image Assembler and others.

Can you define what you mean by failed?  How about posting an image or two demonstrating the problem.

Orthographic stitching is the hardest to do because you're always going to have parallax issues.

[OldRoy]

Luigi,

I think there are two possible approaches:

1. declare a very narrow FOV, like less than 5°. The effect is as if you had made the shots from very far away,

I have used this approach with PTGui when stiching scanned sections of a very wide printed panorama. Not exactly the same, but it did work.
FWIW
Roy

[Dave Carter]

Hi Luigi,
I agree with Gabor.
I have only done it once.  After playing around for a while - it worked quite well.  But, took a lot of pictures.
It was a picture of a large picture in a museum.  Of course, lighting wasn't great but they did not leave me use lights or flash.
What I ended up doing was:
1.  Used my longest lens - about 210mm.
2. Took very overlapping pictures from about 12 feet away.  I had a piece of masking tape on the floor that was parallel with the wall.  And I kept the front two legs of my tripod just at the edge of the tape as I moved along sideways.  I also raised and lowered the tripod column via a longer custom center column (pipe).  Had to be very careful of movement.  After taking each shoot, I checked it on my laptop before moving on to get a good sharp one.   I have an Alpa TC12, so used the viewfinder cross-hairs to locate each shot.
3.  Brought all the pictures into Photoshop after Lightroom conversion.  In Photoshop, I cropped each image to end up with only about the middle quarter (linear) of each picture.
4.  Then stitched these.

Good luck,
Dave

[BernardLanguillier]

And question #2:
If there is no simple or acceptable way to automate the stitching then I'll be forced to manual-stitch, I know soem photographers are very good at manual stitching so I need to know how to start, any book? tutorial? pointers to start with manual stitching?

Thanks for any help you can give me!
Luigi

There is some info on this on the PTgui website, to cut a long story short, specify a focal lenght of 1000mm.

Cheers,
Bernard

[Ben Rubinstein]

There is some info on this on the PTgui website, to cut a long story short, specify a focal lenght of 1000mm.

Cheers,
Bernard

Yup, had this problem when I was using the Camera Fusion adaptor and flat stitching, solution was that given by Bernard above. I was using Autopano pro incidentally.

[MarkL]

I second Jeff's suggestion to try Photoshop's PhotoMerge.  I don't know when the feature appeared, but the version beginning with CS3 (or later) is the one you want to try.

Thirded. I've used photoshop to stitch flat images with no problems at all.