I recently read an article from Photo Life, a high quality photo magazine, on photo merging technique from its February/March issue. It highlights tips and guidelines on creating a true panoramic photo from several similar scenic shots. I tried them, and absolutely loved them. Here we go. I'm going to share what I've done and the steps I took with you. Hope you'll find them useful in your own photo creation. I used Photoshop CS4 photo editing software. You probably can achieve the same results using older version of Photoshop or other photo editing software.
Step 1: Open all images to be merged. Browse to File > Automate > Photomerge, and click on Add Open Images. There're a few different layouts you can play with. Choose Auto for optimal results. This step may take a while to complete depending on how many images you're merging. I used the images of Tokyo Tower I took during my trip to Tokyo last year.
Step 2: Convert the resulting image to Smart Object. Browse to Layer > Smart Object > Convert to Smart Object. During this step, all the image layers generated by Photoshop are merged into one.
Step 3: Straighten object lines. Some objects in the resulting image are not exactly at the right angle due to different focal lengths used in the merging shots. To straighten them, Edit > Transform > Warp to bring up Warp tool that allows you to adjust object lines up, down, left and right. The best way to do it properly is using Grid view (View > Show > Grid) to see your horizontal and vertical lines as reference point. This step may be time consuming; however, if all your shots were taken at the same focal length on a tripod, you may not have to do much here.
Step 4: Crop image for final editing. Once you're happy with the image, you can crop it to the desired ratio. There you have it. Here's the final panoramic photo of Tokyo Tower view.