A Challenging Panorama
Until now, we have panoramas from either two photos or from photos of natural settings that have few image-matching problems. What happens when you have photos that contain hard geometric lines? Let's find out.
The next panorama is made from three photos taken inside the historic Driskell Hotel in Austin, Texas. An image containing many subjects with hard lines and patterns can present some unique challenges, all of which can be overcome using Photoshop Elements:
When the files Hotel Left, Hotel Right, and Hotel Middle are loaded using Create Photomerge, they sometimes will automatch incorrectly, as shown in Figure 11.14. When this happens, it is a simple matter to grab the individual photos with the Move tool and drag them to the thumbnail gallery above the main workspace, as shown in Figure 11.15. It isn't necessary to move them all up therejust enough so that you have room to move and match the pieces.
Figure 11.14 Sometimes, the automatching feature of the Create Photomerge command gets confused and needs help.
Figure 11.15 By dragging the photos to the preview area and bringing them back one by one, most times it's possible to assist automatching and have it work great.
The next problem is that the normal stitching of the Photomerge cannot correctly compensate for the distortion of the wide-angle lens and the close proximity of the subject as shown by the part of carpet pattern that doesn't match (see Figure 11.16). Another problem of the image is that it has too much overlap.
Figure 11.16 Using the Normal setting causes a mismatch where the carpet and ceiling in the different panels meet.
If you change the setting from Normal to Perspective, the program attempts to distort the end panels so that the perspective of the different panels match, as shown in Figure 11.17.
Figure 11.17 Looking like a bow tie, the Perspective setting looks weird, but the carpet and ceiling panels of the panorama match better.
When the Perspective button is enabled, another option becomes available: Cylindrical Mapping. This option flattens the image, much like you would flatten out a map of the earth to display it. The result with the hotel panorama also looks a little weird (see Figure 11.18), but it produces a smooth transition between panels.
Figure 11.18 Cylindrical Mapping reduces the transition, but as we will see, it exacerbates another distortion.
Figure 11.19 shows the panorama created using the Cylindrical Mapping setting after it is cropped. Notice the bending distortion in the carpet and the ceiling. Sometimes, the content of the image does not give you the option of using Normal mode. Figure 11.20 shows the resulting mismatch of the floor pattern using the same panorama content, but with Normal selected instead of Perspective.
Figure 11.19 The Cylindrical Mapping flattens the panorama but introduces a fish-eye type of distortion in the middle of the image.
Figure 11.20 Here is a close-up of the type of mismatch that can occur when either of the two perspective options is not used.