Combining Stacking with Stitching

[georgedingwall]

Hi all,

I've been playing with a new technique, at least for me, involving using the normal stacking method I use and the ability to stitch images into a panorama.

I've been thinking about doing this since I put together my home made focussing rail. The precision milling table I use can be adjusted in both the logitudonal axis and the lateral. However, the only use I ever made of the lateral adjustment was to do a bit of centering of the subject in the field of view.

A second thing that struck me, is that when you go in close for a stacking sequence, you don't see very much of the rest of the subject. It seemed to me that, with some subjects, making a panorama out of several stacks might give an interesting result.

Anyway, I've just done my first test of this method. I used my Nikon D200 fitted with a Sigma 150mm macro lens. I chose this because I thought it would be better not to go in too close for this initial test. It also meant I could make the stacks with fewer frames.

The test subject is a piece of a Hazel branch and was imaged at 1 to 1 for each of the stacks. The stacks were processed in Helicon focus.

To keep things simple I made just three stacks, with a 50% overlap between each lateral movement. The images shown below have not had any additional processing after stacking and stitching. I also used the same Jpeg compression for the images.

I stitched the three final images from each stack using Panorama Factory V4.

The first image below shows the stitched result. (The full size version. 915KB, is at this link.)


The second image shows the three individual stacks that the panoramic image was made from. Each stack was made from 7 frames with 0.5mm adjustment between each exposure. The images shown are full frame from the camera without any cropping.

The Panoramic Image.



I think this technique has possibilities with the right subject. Maybe a caterpillar, millipede or other subject that is much longer than it is thick. If I find a suitable subject I'll try to go in close to see what sort of results might be possible.

[rjlittlefield]

I think this technique has possibilities with the right subject.

Yes indeed, lots of possibilities here!

One big charm for me in stitched "panoramas" is the incredible resolution you can get. To see what I mean, visit this URL and click on the image to see full detail (caution, 7MB download). It's 9179 x 4077 pixels -- prints 30.6 inches wide at an honest 300 dpi. With that much resolution combined with the lack of film grain, the picture looks like it came from fine grain 4x5 film, maybe bigger. But in fact the source was a 4x4 array of images from my Canon 300D.

With gift-giving holidays coming up soon, I've been working up to a correspondingly high resolution macro shot. It's not the right time to give away too much info, but imagine an entire moth wing rendered sharply enough to see the striations on the scales, like the third image here. This is gonna be fun!

--Rik

[georgedingwall]

Hi Rik,

To see what I mean, visit this URL and click on the image to see full detail
--Rik

That's some image. As you say, the level of detail you get in stitched panoramic images is virtually unlimited.

I look forward to seeing your holiday images in due course.

Bye for now.

[rjlittlefield]

I look forward to seeing your holiday images in due course.

George,

I'll be happy to post out both the images and the technique.

One thing I can say right now is that I've been pleasantly surprised with how painless the stacking/stitching process has been in my recent tests.

My first high quality stitched panorama was back in 2000, using scanned film and the command-line Panorama Tools (PToptimizer and PTstitcher). 2 rows of 12 frames. Talk about tedious! Back then the whole process was essentially manual -- pick control points by hand, brush masks to hide the seams. Nice results, but way too much work to justify except as a "labor of love".

Fortunately, a lot of software can get developed in six years if people care, and it turns out there are quite a few people who care about panorama stitching. A couple of key algorithms and many lines of code later, stitching well-shot panoramas from a digital camera is now pretty much a matter of pushing the "go" button.

I was a bit worried that the algorithm for finding control points might have trouble with a subject like a moth wing, which gives the impression of having a very regular pattern in places. That worry proved to be pointless. In fact the pattern is not nearly as regular as it might seem at first glance. PTGui made no mistakes at all.

Bottom line was that my 3x3 test array stitched up fully automatically with no visible seams. I can see a small amount of geometric mismatch between tiles if I layer and flash between them in Photoshop, but only a perfectionist would care. (Who, me?)

It'll be interesting to see how things scale up (pardon the pun) to what I actually have in mind. I'll let you know what technical wrinkles turn up.

--Rik

[georgedingwall]

Hi rik,

Does PTGui automatically stitch the array, or do you have to stitch each row separately and then rotate the rows and stitch after rotation.

I ask, because Panorama Factory is first rate at stitching a single row, but it is quite a convoluted procedure to do a multi row array of images.

What exactly do you need to run PTGui. Would I need to download panorama tools and then PTGui. I sort of remember using panoram tools a long time ago to correct barrel distortion on wide angle shots of buildings. I must have deleted it as I can't find it in my downloads folder.

Bye for now.

[rjlittlefield]

George,

PTGui automatically stitches the array. It's no more trouble to do 3x3 than 1x9.

PTGui is self-contained now. It can still use Panorama Tools and some other independent applications as helpers, but Joost Nieuwenhuijse (the author) has done a great job independently re-implementing, with improvements, all of the operations that are needed: finding control points, optimizing geometry parameters, remapping images, color correction, and blending. He has also added a Project Assistant that simplifies getting things together. It's really a tour de force.

I just now re-tested, starting from scratch with my original 6 images output from Helicon Focus. (I mis-typed earlier when I wrote "3x3 test" -- it was really 2x3.) Using PTGui 5.8.4 (not the latest), quite acceptable results popped out when I just used the Project Assistant to Select Source Images, Generate Control Points, and Create Panorama. No manual intervention, maximum control point error 4 pixels in 8000 pixels image width.

--Rik

[augusthouse]

Hi Rik,
How is the moth wing project going? I am really interested in seeing the results and the techniques employed or devised.

Stacking and Stitching what a perfect combination.

Craig Gerard
Australia