Stitching Software and Overlap

[sanking]

Do stitching softwares vary in terms of the amount of overlap needed for the two images? I have been scanning some 56 mm wide negatives in two passes where the widest scanning area is 30mm , and stitching them in Photoshop CS3 with Photomerge. It is something of a hit and miss game as to whether Photoshop will merge the files automatically because the overlap is so small so I am wondering if there is something out there that needs less overlap. I know there is some overlap because in every case where Photoshop would not merge the stitches I have been able to do so manually.

Sandy King

[Kirk Gittings]

I have had some really inconsistent experiences with that issue. For example I have had images that PS could not find the common points while AutopanoPro could and vise versa. It seems to be related to how strong the detail is in the overlap that it needs to latch on to. A highly detailed small overlap works better with PS than a large blank wall overlap. Sometimes it even seems a bit counter intuitive too. As an example I had a flat stitch where there was great overlap of a blank wall and no program seemed to be able to make it work. Out of frustration I cropped out allot of the overlap-still blank wall-and then PS made it work.

So basically my routine is to see if it will work in PS (which works for me 95% of the time) and if not try another program.

I am struggling right now with an image that is basically a 6 frame DSLR cloudscape with a touch of land a the bottom. It combines fine even though there is minimal overlap as there are considerable strong cloud edges throughout, but the stitch has obvious density edges along the edges of the tiles in the skies. There is no obvious reason for this as exposure and white balance was locked down. Maybe more overlap would have helped? I don't know as yet.

[sanking]

I have had some really inconsistent experiences with that issue. For example I have had images that PS could not find the common points while AutopanoPro could and vise versa. It seems to be related to how strong the detail is in the overlap that it needs to latch on to. A highly detailed small overlap works better with PS than a large blank wall overlap. Sometimes it even seems a bit counter intuitive too. As an example I had a flat stitch where there was great overlap of a blank wall and no program seemed to be able to make it work. Out of frustration I cropped out allot of the overlap-still blank wall-and then PS made it work.

So basically my routine is to see if it will work in PS (which works for me 95% of the time) and if not try another program.

I am struggling right now with an image that is basically a 6 frame DSLR cloudscape with a touch of land a the bottom. It combines fine even though there is minimal overlap as there are considerable strong cloud edges throughout, but the stitch has obvious density edges along the edges of the tiles in the skies. There is no obvious reason for this as exposure and white balance was locked down. Maybe more overlap would have helped? I don't know as yet.


Kirk,

I wonder if changing layer from Normal to Difference before trying Photomerge in Photoshop might help? This would create more contrast difference between the two files. Or is there a way to do this with Photomerge and then change the Difference layer back to Normal?

Sandy

[sanking]

Kirk,

I wonder if changing layer from Normal to Difference before trying Photomerge in Photoshop might help? This would create more contrast difference between the two files. Or is there a way to do this with Photomerge and then change the Difference layer back to Normal?

Sandy

Answered my own question on that. Did not help at all.

Sandy

[percepts]

providing the rotation of neg doesn't alter from one scan to the next and the scan settings remain the same, then it's easy to pixel align the two halves of the scan manually. Just zoom in to 800% or more so you can see pixels on the screen and position edges using arrow keys.

You only need stitch software when joining two different negatives because of the distortion caused by the lens. In that case the stitch software needs to move stuff about. But when it's two scans of a single neg it only needs to pixel align providing the orientation from one scan to the next hasn't altered.

I have done this when scanning prints. I just slide the print along the edge of the scanner platten so that alignment remains the same.

[sanking]

I have been stitching layers manually for many years, and as you say, if alignment is same for the two negatives it is easy. Unfortunately, my method of scanning using a glass plate and templates with visual registration results in slight differences of alignment that make manual stitching a bit complicated. Bottom line is that Photomerge does a much better job than I can do manually, when it works.

Sandy King



providing the rotation of neg doesn't alter from one scan to the next and the scan settings remain the same, then it's easy to pixel align the two halves of the scan manually. Just zoom in to 800% or more so you can see pixels on the screen and position edges using arrow keys.

You only need stitch software when joining two different negatives because of the distortion caused by the lens. In that case the stitch software needs to move stuff about. But when it's two scans of a single neg it only needs to pixel align providing the orientation from one scan to the next hasn't altered.

I have done this when scanning prints. I just slide the print along the edge of the scanner platten so that alignment remains the same.

[Donald Miller]

Sandy, Kolor (Autopano) has a couple of new programs up on their website

http://www.autopano.net/en/

I believe the "download" will allow one to try the programs prior to purchase. I have the pro version and have no complaints on the results. I usually allow about a 20% overlap (depending on lens and index plate) on my pano head.

[sanking]

Sandy, Kolor (Autopano) has a couple of new programs up on their website

http://www.autopano.net/en/

I believe the "download" will allow one to try the programs prior to purchase. I have the pro version and have no complaints on the results. I usually allow about a 20% overlap (depending on lens and index plate) on my pano head.


Donald,

Thanks for the info. I will download Autopano and give it a shot. Do you know off hand if the latest version of the software is available for MAC?

Sandy

[Donald Miller]

Donald,

Thanks for the info. I will download Autopano and give it a shot. Do you know off hand if the latest version of the software is available for MAC?

Sandy

Sandy,

Yes I noted that they do support Mac.

Best regards,
Donald Miller