63  Stitching Software

1 Can‘t See the Forest for the Trees … Shot Using: D70, Nikkor AF-S f3.5-4.5/24-85 mm zoom Liepaja, Latvia lens, hand-held, 5 images using a 24mm Stitching Software: PTMac (alignment, blending), Photoshop (parallax error corrections, image fine-tuning) Projection Type: Cylindrical, 150° × 35° 64 Stitching Software Don’t Lose Your Way in the Software Jungle 65

Internet Forums process itself. The handling and performance of these programs is as varied as their design • International VR Photography Association: and price range. Most programs offer free http://ivrpa.org/forum downloadable test versions, and most are • Panoguide: http://www.panoguide.com/forums also supported by Internet forums, managed • Panotools: either by independent third parties or even http://tech.groups.yahoo.com/group/PanoToolsNG by the software manufacturers themselves. • Quicktime VR: A little time spent surfing through these http://lists.apple.com/mailman/listinfo/quicktime-vr forums will help you decide whether a par- • PTMac: http://www.kekus.com/forum ticular program suits your level of creativity • Autodesk Stitcher: http://discussion.autodesk.com/forums and experience, and whether the accompa- • PTGui: http://groups.google.com/group/ptgui nying documentation is appropriate to your 1 • Max Lyons: http://www.tawbaware.com/forum2 personal style and workflow. Editor in the 2.6.1 version of the program

Don’t Lose Your Way in the Software panorama fans. His program also provided a Tools for Apple Macintosh, introduced in Software Diversity Jungle strong impulse for the further development 2002) are both based entirely on Panorama of panorama software in general. Panorama Tools and are still clearly related to the origi- Working with a computer is a highly signifi- The introduction of Apple QuickTime in Tools is basically a loose collection of soft- nal program. cant part of the process of creating digital 1991 was one of the major starting signals ware tools designed to distort, correct, align, REALVIZ Stitcher (now called Autodesk from multiple source images. for the subsequent development of multi- and transform digital images for the spe- Stitcher) was probably the first generally So why are we dedicating so much time and media software. QuickTime VR appeared in cific purpose of creating digital panorama available, modern spherical panorama stitch- column space to theory? Firstly, it is simply 1994, and QuickTime VR Authoring Studio images–with excellent results. The only ing program with a user-friendly GUI. While interesting to understand the background (QTVRAS) followed in 1997. QTVRAS was problem is that the tools themselves are not Panorama Tools (and others) offered purely 1 QuickTime VR and the connections between the individual the first commercially available software easy to operate and do not have their own manual panorama stitching functionality, Authoring Studio parts of the process; and secondly, it would that enabled users to create 360° panoramas graphical user interface. In order to operate REALVIZ offered a highly automated stitch- otherwise be too easy to become disori- using computer technology instead of spe- the tools effectively, you need a fair amount ing process without manual control point ented by the complex choice of processing cial , and to display the results as a of background knowledge, and you must also functionality. Image alignment was also per- options and parameters offered by profes- rolled-flat, cylindrical image or interactively use a command line to execute some tasks. formed semi-automatically, and was unfor- sional stitching software. Some background on a computer monitor using QuickTime The main aspects of the necessary back- tunately not always reliable. Until recently, if knowledge helps you to avoid making basic Player. Since the introduction of QuickTime ground knowledge have been addressed you wanted to produce high-quality panora- mistakes from the outset, or at least allows 5 in 2001, 360° × 180° panoramas can also be graphically (if not mathematically) in the mas for printing, you would most likely end you to correct your mistakes effectively dur- viewed interactively. These days, there are a previous chapters, so you shouldn’t have up using a program based on one of Professor ing the stitching process, making the results multitude of stitching and viewing programs much trouble coming to grips with the fol- Dersch’s algorithms, in spite of the steep produced by the computer sometimes less of available, often in the form of Java Applets lowing sections. Additionally, in order to learning curve involved. a surprise. and Shockwave or applications. allow non-physicists and non-programmers All of these tools were part of the early Stitching software is available in many In 1998, mathematics professor Helmut access to these great tools, various groups development stages of digital photographic forms–from free, highly specialized open- Dersch at the University of Furtwangen in have programmed user-friendly GUIs for blending techniques. They demanded perfect source algorithms right up to complex (and Germany introduced his Panorama Tools the Panorama Tools algorithms. PTGui parallax correction and , as well as sometimes expensive) software suites that software suite. He has since earned himself (Panorama Tools Graphical User Interface, excellent alignment and composition on the offer functionality way beyond the stitching a legendary international reputation among introduced in 2000), and PTMac (Panorama 66 Stitching Software Don’t Lose Your Way in the Software Jungle 67

part of the photographer, in order to produce at various stages in the stitching process. You error-free panoramas. can enter lens correction parameters manu- Without going into too much detail, ally, and, should you not want to use the we now compare four currently available, program’s built-in control point generator, professional-level stitching programs that you can align your individual source images offer very different handling characteristics by manually entering tilt, pan, and roll coor- and diverse functionality. But before we go dinates, with the mouse, or by selecting your any further, we would like to point out that own control points. You can also use addi- recent developments in stitching software tional plug-ins, such as Autopano, Enblend, algorithms have led to an ever-increasing or Smartblend, to control the alignment and level of fault tolerance for the overlap areas blending processes. in panorama source images. Until recently, it The 7.0 and 8.0 versions of PTGui signifi- was necessary to shoot precisely aligned and cantly increase the program’s range of func- exposed source material in order to produce tionality and go a long way beyond simple acceptable results. Modern blending algo- panorama stitching. Constant program rithms, such as Enblend and Smartblend, maintenance and fine-tuning has markedly can produce astonishing results even if the improved the automatic control point selec- source material is not of optimum qual- tion function, the program’s own blending ity. We can be fairly certain that the avail- algorithm, and general processing speed (no able blending algorithms will continue to need to be scared of gigapixels!). The pro- improve, and that the near future will bring gram now includes built-in QuickTime VR 7 PTGui Pro even more exciting developments. functionality, allowing you to output images User interface in directly to the interactive digital panorama Advanced mode The Perfectionist: format without having to use additional, New House Software – external tools. PTGui Pro While most stitching programs only adjustable Vedutismo projection type, these In a nutshell: PTGui is very fast and offers PTGui is well-known and offer the three standard projection types projection types offer a real plus when it an extremely wide range of useful functions. extremely popular among (flat, cylindrical, and spherical), PTGui has comes to producing printed output. Once you get used to the somewhat cryptic professional panorama pho- included Mercator and fisheye projection The automatic EXIF data recognition user interface, it quickly becomes a pleasure tographers. Although it had its origins as a for a while now, as well as various trans- function helps to realize large stitching to use the program to produce perfect pan- GUI for Helmut Dersch’s Panorama Tools, it verse projection types for use with vertically projects at least semi-automatically, and the oramas. is constantly being developed and expanded, stitched panoramas. The Mercator projection program‘s outstanding batch and template and is now only loosely based on the original. produces similar results to a cylindrical pro- functionality allow you to render hundreds The Ghost Buster: Today’s PTGui not only includes all of its jection, but with significantly less distortion of projects overnight. Additional support for Autodesk (REALVIZ) Stitcher original (and complex) command line-based to the upper and lower edges of an image; it HDR and bracketing sequences rounds out Bought by Autodesk in 2008, stitching tools, but also a suite of automatic, is thus a very useful addition for producing PTGui’s functionality, which also includes this program was probably GUI-based tools for aligning and merg- printed panoramas. The program even allows Exposure Fusion algorithms as an alternative the first to offer user-friendly ing images. As we have already noted, no you to alter the degree of stretch for flat and to Classic HDR image production (which is support for multi-row pan- software-based process is perfect, and it can cylindrical projections, thereby reducing the often complex to handle and sometimes pro- orama production. The program’s user sometimes fail completely. For this reason, extreme distortion often found at the edges duces rather garish results). interface and handling can still be described PTGui allows the user to intervene selectively of stitched images. Together with the also as ground-breaking. The Stitcher workflow 68 Stitching Software Don’t Lose Your Way in the Software Jungle 69

The program offers flat (here, confusingly creation of 3D and multimedia applications. called “snapshot”), cylindrical, and spherical This strategy ensures that the program projection types. includes a well-designed and easy-to-use But Stitcher has more than just these basic interactive panorama export function. panorama functions. Moving objects (such as people or vehicles) can often produce “ghost” The Blender: images in a panorama. Stitcher includes a special “Stencil” tool which can be used to Photoshop has been around mask image areas affected by ghosting before for more than 20 years, and its rendering, causing them to be left out of the comprehensive functionality final panorama image. This is a very practical is continually being devel- alternative to complex Photoshop masking oped and extended. The program is generally procedures. accepted as being the de facto standard image Stitcher also offers comprehensive processing program for today’s advanced QuickTime support, including the compres- user. Before the CS3 version was introduced, sion mode, zoom, window size, and start Photoshop had little to offer for the modern position settings necessary for producing “-stitching” digital photographer. The effective interactive output. If your pan- results produced by the Photomerge com- 3 orama does not include zenith and nadir mand were always fairly basic, and often left Autodesk image data, you can limit the visible view- a lot to be desired with regard to alignment (REALVIZ) Stitcher ing area so that the upper and lower edges and stitching accuracy. This all changed with Live Preview of the of your panorama do not appear empty and the introduction of Photoshop CS3 and the aligned source images black in the viewer. You can set QuickTime new, separate Auto-Align and Auto-Blend panoramas to rotate automatically as soon as tools. they are fully loaded into the viewer. Stitcher The best part first: The Auto-Blend Layers is dominated by the constantly visible Live images using individual control points. The allows simple creation of hotspots, which command merges multiple Photoshop lay- Preview of the source images and their posi- great advantage of this program is that you allow the viewer to jump from panorama to ers and delivers excellent results quickly, tions in relation to each other. It is simply can combine various alignment methods, panorama as if they were connected using even when blending large source files. A a lot of fun using the program to align your using semi-automatic or manually selected conventional hyperlinks. This is a simple slight disadvantage of the command is that images, select a horizon, view the effects of control points to correct any errors that and effective way to create extensive virtual it is only really designed for stitching partial converging lines, or zoom in and out of the the automatic mode might produce (if, for tours. panoramas; it cannot blend the “end” seams current image. example, too much blue sky causes automatic In a nutshell: Stitcher’s graphical interface of a 360° image, making it less useful for Stitcher now supports various alignment alignment to fail). makes it easy for beginners and experienced producing interactive QTVR panoramas. The methods, including a fully automatic mode Stitcher provides automatic recognition of photographers alike to produce great pan- Extended version of Photoshop CS4 includes and a semi-automatic mode that allows the and lens details via EXIF, and auto- oramas. A real standout feature is the Stencil 360° blending functionality within its 3D and user to select the rough positions for the matic distortion correction for your source tool for removing ghosting. As with most technical imaging toolbox. source images, and then leaves the fine- images. The program also allows the user other “automatic” programs, Stitcher only The Auto-Align Layers command (which tuning to the software. If the source images some manual intervention at various stages, allows a limited degree of control over the is actually used to align and straighten have a sufficient number of unique features, should it be necessary. processes involved. the source images before the blending the fully automatic process usually produces Autodesk’s product development strategy step) unfortunately displays all the known excellent results. You can also align your means that Stitcher is firmly aimed at the weaknesses of fully automatic tools. The 70 Stitching Software Don’t Lose Your Way in the Software Jungle 71

7 Autopano Pro User interface in Edit 1 Photoshop CS3 mode Automatic image alignment dialog box command offers a choice of projection types, out the final blending step in order to blend but that’s it. There is no way to tweak the the final panorama using either Photoshop then import them into Photoshop to repair, work around the camera rather than the horizon, converging lines, or the starting layers or multi-TIFF export with the Auto- manipulate, and optimize the individual lay- computer. The photographer is left to con- point, and the results are, at best, mixed. Blend command instead of the program’s ers, before using Auto-Blend to produce the centrate on making great source images, and Even the addition of spherical projections own algorithm. This extra step is often worth finished panorama. Autopano does the rest–automatically and and support in CS4 has not the additional work involved, especially if excellently. improved the general quality of Photoshop’s you have to deal with moving objects in the The Robot: Unusually, Autopano is not designed to results. The program sometimes works fine seam areas, or other details that need to be Kolor Autopano Pro process one panorama after another, but and sometimes fails completely. The manual manipulated on individual layers. Autopano Pro is one of the rather to take an overview of all the available Reposition option is designed for use with In a nutshell: Photoshop offers a great newer contenders in the material. It uses EXIF data to identify source specialized cameras with removable backs, or blending algorithm, but lets itself down stitching software market. It images that belong together, then automati- for the adjustment of scanned source images; when it comes to image alignment. However, left a lot of the competition cally sorts them into pre-stitched preview however, it doesn’t help DSLR photographers it is unbeatable as an element at the post- standing when it was introduced in 2005 and panoramas. If the source material is well- who pan the camera, as it doesn’t include any processing stage in the panorama workflow. quickly became a firm favorite among pan- defined, this process can work for hundreds perspectival transformation functionality. Use the multi-TIFF option within your dedi- orama photographers. The program’s most of images in a single folder. The program Professional stitching programs (such as cated stitching software to export the trans- important feature is its workflow, which is automatically recognizes 360° panoramas, PTGui or Stitcher) offer the option of leaving formed and aligned source images. You can designed for photographers who center their partial panoramas, and HDR panoramas 72 Stitching Software The Dilemma, Part 2: No Software is Perfect! 73

consisting of multiple bracketing sequences. processing power available) to stitch unlim- Exposure Fusion–Producing HDR Images Without Using HDR Techniques You can, for example, start the identification ited numbers of source images into a single process in the evening and view your entire panorama. The Giga version has better sup- A general problem often encountered in many photo- A relatively quick and simple approach to the high- collection of new, automatically generated port for motorized VR heads, and also shifts graphic situations is handling a high range of contrast contrast problem is provided by recently developed panoramas the next morning. Very handy! the software emphasis from printed output within a single image. This problem is especially relevant “exposure fusion” algorithms. This technique is based on While professional panorama photogra- to the production of interactive VR panora- for panorama images; a single panorama can often scientific research done by Tom Mertens, Jan Kautz, and phers tend to use manual exposure mode to mas and Internet-based virtual tours. The cover objects in dark shadows right through to those lit Frank van Reeth. Similarly to HDR techniques, it produces create their source images, less demanding program makes it simple to create hotspot by direct sunlight. No known film or can high-contrast images by merging multiple source images. users often rely on the camera’s automatic links between individual panoramas, and the directly capture such a high range of contrast. This issue The difference between this and more well-known HDR exposure features while shooting. Autopano’s entire tour is saved in the widely-used Flash has been the subject of intense discussion in recent techniques is that exposure fusion does not require the developers had exactly these photographers format. years, and the processes that have been invented to work use of an intermediate 32-bit image. The Enfuse algo- in mind when they designed the program’s In a nutshell: Some of the best technology around it are now generally addressed using the label rithm, for example, uses the same bracketing sequences ingenious automatic and exposure available today is at work behind Autopano’s High Dynamic Range (HDR) photography. as its source material, and calculates the individual correction features. Autopano can often simple interface, including the SIFT control This new process involves shooting traditional brack- according to the exposure, contrast, and saturation values turn image sequences that include large dif- point extractor and the Smartblend blend- eting sequences, then merging them via an intermedi- present in the source pixels. In spite of its simple interface ferences in image brightness or color tem- ing algorithm. Together with the program’s ate 32-bit image and an additional process known as and limited user-controllable parameters, Enfuse pro- perature into perfectly acceptable finished automatic color and exposure control func- “tone mapping”. The new image simultaneously displays duces pleasing, remarkably balanced results which are panoramas. tions, these technologies produce first-class adequate detail in shadow and highlight areas. There often of better quality than equivalent tone-mapped HDR Although Autopano is clearly aimed at pro- results, even in Auto mode. The potential for are various specialized HDR programs available, such as images. ducing panoramas automatically, the results user intervention in Autopano is (intention- Photomatix (www.hdrsoft.com), FDRTools (www.fdrtools. Enfuse and other exposure fusion algorithms are still in it produces sometimes need manual fine- ally) limited, which sometimes makes more com), and Picturenaut (www.hdrlabs.com/picturenaut). their infancy, but already represent a significant advance tuning. Here, you need to delve further into complex projects difficult to realize. Photoshop also includes some HDR functionality within in panorama techniques. Many developers are constantly the program’s internal workings. Autopano its broad range of tools. HDR techniques are generally programming new, user-friendly interfaces and plug- offers a similar level of user-controllable well suited for use with panorama techniques, but are ins for their algorithms, and you can check out the cur- functionality as Autodesk Stitcher, but it The Dilemma, Part 2: quite tricky to apply, and often produce a surreal, over- rent state of affairs in the PanoTools Wiki at: http://wiki. doesn’t allow the user to intervene as much No Software is Perfect! saturated “HDR look” in the final image. panotools.org/Enfuse. PTGui and the Photomatix HDR as more sophisticated programs. The pro- software package already include built-in exposure fusion gram’s basic philosophy of simple, automated In order to create a seamless panorama from functionality, which is very useful indeed! panorama production becomes more obvious two or more adjacent image segments, the when you need to tweak your images your- images need to be corrected, transformed, self. aligned, and finally merged into a panorama Other aspects of the program’s handling using specialized stitching software. results if no unforeseen circumstances intro- latest at the post-processing/image process- are great, and include a History function for Different programs use different duce errors into the process. The problem ing stage. retracing your processing steps when your approaches and handling methods to execute here is that manual user intervention is often The stitching programs available on today’s image doesn’t turn out as you had hoped. these steps. These days, a purely manual not possible, and errors cannot then be cor- market can be broadly divided into two Version 2 of the program has seen the workflow, as supported by Panorama Tools, is rected once they have occurred. If your proj- types: manually controlled programs, such product line expand to include Autopano a thing of the past. All contemporary stitch- ect is technically ambitious or was carelessly as Panorama Tools or PTGui, which include Giga, which has extended functionality. ing programs have integrated automatic shot, it is more likely that stitching errors some automated tools but allow manual Both Pro and Giga versions are suitable for functions (for example, for selecting control will occur. The user has to learn to recognize adjustment of every step of the panorama producing gigapixel panoramas, and allow points), and some programs work fully auto- and correct these problems–ideally before creation process; and highly automated pro- you (depending, of course, on the amount of matically, which can also produce excellent the actual stitching takes place, but at the grams, such as Kolor Autopano, Autodesk 74 Stitching Software The Dilemma, Part 2: No Software is Perfect! 75

Stitcher, and Adobe Photoshop, some of results produced by the program are usually image quality which allow manual adjustment of some very good. aspects of the stitching process if necessary. PTGui is the real perfectionist amongst Manually-controlled programs rely more on today’s stitching programs, and is augmented in-depth user knowledge and hands-on inter- with a good set of automatic functions while action, but a skillful user can adjust optical still allowing the user full manual control of errors, image alignment, image output, or the process. The program’s interface appears Optimizer control to successfully stitch just somewhat dated but, with the help of a little about any project. background knowledge, the program never- Five years ago, the differences in quality theless produces perfect stitching results, between the results produced by the various and there are virtually no stitching situations panorama programs were significant. Now, that PTGui cannot handle. Additionally, the better blending algorithms help the user program’s developers are constantly improv- to produce increasingly consistent results. ing and updating the tools and algorithms Photoshop PTGui, Autopano, and Autodesk Stitcher built into the package. manual controls allow you to chooose between different Why is it so difficult to compare the perfor- algorithms, such as Enblend or Smartblend, mance of different panorama software prod- better automatic and you will simply have to experiment to ucts? All modern programs can easily handle Autodesk Stitcher workflow find out which produces the best results for simple situations in which a panorama PTgui each individual project. Photoshop’s Auto- head and a (relatively) long lens with no sig- Blend blending algorithm delivers stunning nificant distortion are used to shoot a subject Autopano results–a true boon to all those who already with obvious, easily-overlapped features. own this (not inexpensive) program. On the The situation becomes more complex when other hand, the Photoshop Auto-Align func- the photographer uses extreme wide-angle tion does not do justice to the rest of the or fisheye lenses, or when the frame includes program, and 360° stitching is only possible objects at close (and remote) distances, or if if you are using the Extended version of the the sequence is shot with little or no regard program. Photoshop is nevertheless the best for the no-parallax point. currently available program for post-process- This is the point at which it becomes ing panoramas. impossible to compare different programs The smooth and modern-looking Autodesk objectively. Every photographer shoots dif- 1 No Software is Stitcher is especially appropriate for photo- ferent subjects under different conditions, features Perfect! graphers who want to quickly and easily pro- and the results must be judged in context. If duce interactive panoramas for direct output you are shooting in a studio, moving vehicles, in QuickTime. people, or clouds are not a problem, whereas The newer Autopano is highly automated objects at multiple distances can be trouble- sky between shots, or to have problems with even the best software can only attempt to and uses some of the best currently available some. On the other hand, if you are shoot- moving clouds or trees. gloss over these errors. Nowadays, you can algorithms to work its magic. Should it be ing a broad landscape, you probably have Some factors are more important than oth- often eliminate “soft” aesthetic factors, such necessary, some manual user intervention no parallax problems, but are more likely ers when it comes to producing the perfect as inconsistent white balance or brightness, is possible, but the automatically stitched to encounter differences in the color of the panorama. Parallax errors or inconsistent at the image processing stage. settings are knock-out criteria, and