Howto Panoramas and Digital Stitching

The joy of Panoramas

How wide is wide? Not wide enough? Panoramic formats like 612 and 617 are great, but sometimes they just aren’t wide enough. Sometimes a 180° view is needed, sometimes 360°, even 360° x 360° fits the bill. Everything the eye can see, any way you turn, the full visual experience captured. This article will provide an overview of the panoramic making process, mainly digital stitched and blended panoramas, covering the software (mostly PC, but also Mac and Linux) and the hardware required to produce high quality panoramas suitable for printing.

Contents

The Options
What you need - Hardware
Modifications
What you need - Software
Taking the photographs
Stitching
Printing
Conclusion
Appendix 1 - Other resources - websites & books
Appendix 2 - Installation instructions for Panotools

The Options

With film you have a range of relatively simple options:

• Swing lens cameras e.g. Noblex and WidePanPro
• Rotational cameras e.g. Seitz Roundshot
  
• Flatback cameras if 617 is enough e.g. Linhof Technorama 617S
  

By simple, I mean simplicity and speed of operation, the cameras themselves are complex and beautiful engineering creations. With digital, the above types of cameras are available, but with price tags that will scare your bank manager. The low cost answer is stitching a series of images. Cheaper by a long way, with the same stunning panoramic results, but a little post production is required. However, modern software tools and panoramic heads make it very simple to produce high quality panoramas in no time at all.

What you need - Hardware

Simple and effective panoramas of distant scenes can be shot with a handheld camera, like Photograph 2, but if there are strong foreground elements, my favourite, then shooting handheld will not yield good results because of parallax error ie as you rotate the camera the foreground elements will move relative to background elements making it difficult for stitching software to produce good results. To avoid parallax a panoramic head is used which works by rotating the camera around the lenses nodal point.

For single row panoramas a simple panoramic head that sets the camera up around the horizontal nodal point is used. Examples of these are:

• Manfrotto 303PLUS
• Kaidan Kiwi

If you want to create multirow panoramas or 360° QTVR or even just be able to tilt a single row panorama to maybe take in more sky or more foreground, then a spherical panoramic head will be required. The first time I saw one of these I couldn’t believe what I was seeing, and the instruction manual looked awful, however things were a lot simpler than they looked to both setup and to use. In fact, after a bit of use, I removed a lot of the un-necessary pieces on my panoramic head, see below. The following are all well respected products:

• Manfrotto 303SPH which is the one I use
• Peaceriver 3Sixty
• The budget and deliciously named Panosaurus

I chose the Manfrotto 303SPH as it gives a lot of setup flexibility to accomodate many cameras from digicams to DSLRs to medium format (many heads only allow digicams or small DSLRs), the cost was mid range and I’ve used and trusted Manfrotto products since starting photography.

You will also need:

• A tripod
• A spirit level

Modifications

Modifying the head will depend on your camera. If you have a digicam or small SLR, there may be simpler products you can buy in the first place, but with the D2X I needed the Manfrotto head, but could remove a lot of parts that weren’t needed and also to reduce weight. The panoramic base with click stops is useful, but not essential and at 700g was a no brainer as to removing it. This part of the panoramic system is probably an expensive part, and as there are a few other parts that aren’t needed for every camera it might be useful if Manfrotto had some sort of online configuration tool that would allow you to select only the parts that you need for your camera and hence save a bit of money and reduce clutter in the drawers of ‘stuff’.

The panoramic head now attaches directly onto my tripod ball head using a ‘200 PL-14 Spare Plate’ which is screwed into the bottom of the panoramic assembly.

I have also replaced the slotted screw that holds the camera to the sliding adjustment plate with a screw from a standard ‘200 PL-14 Spare Plate’ that has a folding head on it to allow easier mounting/unmounting from the camera.

What you need - Software

There are quite a few panoramic stitching programs out there. Photoshop CS and Elements both contain basic stitching actions, but I’ve never found them to work all that well, and they only produce 8 bit files. Apologies to Mac users now, I’ve only experience of PC programs, but I some of the programs I mention are available for Mac and Linux too.

Below are the programs I have used and my opinions of them. However everyone is different so you are best to download the trial versions and give them a spin yourself. I have used Panotools for a few years now, so some of my criticisms on other programs will probably be out of date.

• Arcsoft Panorama Maker - This simple and effective program that comes with many digital cameras. Limited to 8 bit files and really slow to use, but the ease of stitching and quality of results is high. Recommeded for beginners or if you have a quick and easy stitch that you need to do. (PC/Mac)
• Realviz Stitcher - An industry standard, especially for producing QTVR files, I found the program slow in use and had a very limited maximum file size it could output for print. Recommended if you only want to produce high quality QTVR files. (PC/Mac)
• Panorama Factory - Despite the slightly cheesy name and website, the program is actually really good and I used it for quite a few years. Offers heaps of controls, good customer support, but it wasn’t always that great at stitching complex panoramas, however, it has been a while since I used it so newer versions maybe better. Recommended for those wanting a lot of control with an easy to use interface. (PC)
• Panotools with PTAssembler - This is a collection of programs often pulling programs out of the open source movement. Be warned, installation and use can still be tricky, but the quality and types of output are only limited by your imagination. I wouldn’t use anything else to produce my panoramas for gallery exhibition, but I often curse the complexity despite being an experienced user. PTAssembler is a graphical frontend for Panotools and makes it relatively easy to produce fantastic panoramas. Recommended if you want the best quality panoramas and have time and computer skills. (Panotools - PC/Mac/Linux, PTAssembler - PC, Hugin - as of 20-06-07 the program has not reached version 1 but is available for all platforms.)

The basic PTAssembler installation program includes everything you need to get going, but if you need any further help have a look at Appendix 2 at the end of this article.

I have also started experimenting with stitching under Ubuntu Linux which has Hugin built in. I’ll report on this (and image processing) at a later time, but initial tests have been positive. (Much like working with Linux itself. I’ve moved all my office, DTP and internet/email work over to Ubuntu Linux and am much happier and productive for it. Image processing is a little more complex though!)

There are other variations on the above tools.

Taking the photographs

This will depend on the panoramic head you are using, but the rough process is:

• Follow the manufacturers instructions for setting up the nodal point for the camera/lens combination you want to use. In practice I find one setup does for all my lenses.
• Go out (or stay inside) and find a scene that you want to make into a panorama.
• Study the scene. Study it some more. Does it need a wide or a long lens? Are there any foreground elements that will make stitching difficult or be visually obtrusive? (e.g. A thick tree trunk that goes from the top to the bottom of the frame is often obtrusive.) What do you want your panorama to show and convey
• Get out a light meter or use your cameras spot meter mode and analyse the scenes exposure and dynamic range.
• The common advice with respect to exposure is to find the desired exposure and set this exposure into the cameras manual mode. This kind of necessitates shooting on flat light days or you can end up with expanses of black shadow and white highlights. Sure, this approach works, but I like to defy convention and find that setting the desired aperture in aperture priority mode gives more even exposure, most of the time. This approach can fail. You may also need to use ND grad filters to control dynamic range, just as you would with a single frame.
• The camera will also need to be set to manual focus. This ensures depth of field and the focus point stay the same which makes stitching easier.
• Beware of wind and light changes. A bulky panoramic head can suffer from a lot of vibration in even low winds. If the light is changing rapidly, in both exposure and white balance, you will either need to work quickly or make a simpler panorama. Trying to process and stitch photographs from these conditions, even if you are shooting RAW, is a frustrating and often results in failure. Photograph 5 consists of about 13 frames, but I actually took about 20. Because of the low position of the sun and the mountain shadows the changes in exposure and light colour were simply too much to achieve a high quality stitch.
• Take the series of photos that you need. Approximately 25% overlap is required between frames.

Stitching

The following tutorial will point you in the right direction for PTAssembler. There is no point in duplicating good content.

http://www.tawbaware.com/ptasmblr_tutorial.htm

Max’s excellent tutorial was really helpful and more than enough to get me going.

When I first started using PTAssembler with 16bit TIFF files there was a workaround for 16bit files which AutoPano didn’t recognise. In the current versions of PTAssembler, Max tells me that PTAssembler will automatically in the background create 8bit files and run these through AutoPano and then apply the control points to the original 16bit files. So, 16bit TIFF files can be used no problems.

I have had problems if I add files that have been heavily processed after RAW conversion, for example, files output from DxO will not stitch at all. I’m not sure why.

Panotools and many of the front end tools are module based. This means the basic program may do image alignment, but if you want better performance you will have to add in other modules. For accurate alignment (from accurate control point placement) I use AutoPano/Auto-SIFT. For good quality blending of the stitching I use Enblend. There are others out there that work equally well.

The process for other programs will be similar.

You should now have a high quality stitched and blended panorama that you can process in Photoshop or similar. If not, drop me an email if you need more help.

Printing

There are a number of options for printing panoramas:

• Print them out using a sheet paper printer and trim the paper to the correct size.
• Use a photo lab. There are plenty online labs that do a great job, but ideally I always like to use a local lab so that I can oversee the results.
• Print them out onto roll paper. There are plenty options out there, both large format and consumer printers. I used the consumer level Epson Photo 2100 for a while (now replaced by the Epson Photo 2400. I currently use the Epson Stylus Pro 4800 which has great features and is cheaper to run than the Epson Photo 2100. Printers by Canon and HP that support roll paper options are also available.

With consumer level photo printers you are limited in the types of paper that are available in roll paper, but there are a myriad of papers in roll form for large format printers. I don’t think there is any particular paper that I would recommend for panoramas, just use your favourite. I usually use Epson Smooth Fine Art papers as the quality is good and they are stiff enough for safe handling but not so thick as to make printing a problem.

Conclusion

It is always satisfying to make a great photograph, but I find it especially satisfying when I make a good panorama. It is not only technically satisfying, but there is something emotionally appealing about seeing the bigger picture.

Got any comments or suggestions? Let me know.

Appendix 1 - Other resources - websites & books

• Panoguide
• Gigapxl
• cliffordross
• Stretch The world of panoramic photography, Nick Meers, Rotovision, 2003 - superb photography and resources section.
• The Worlds Wild Places, Colin Prior, Constable, 2006 - not that wide, but Colin has truly made the 617 format his own. A lot of the content in this new work is stitchers. Starting with Scotland in early books, this new book shows a new level of mastery and love for the land.

Appendix 2 - Installation instructions for Panotools

21-06-07 NOT REQUIRED NOW [Small PanoTools
Source:
http://www.tawbaware.com/maxlyons/pano12ml.htm
File:
http://www.tawbaware.com/maxlyons/panotoolsml.zip
Instructions:
Pano12.dll should be placed in the Windows “system” directory (typically c:\windows\system32), and PTStitcher.exe and PTOptimizer.exe can be placed in any other directory.
Create Program Files\PanoTools, but it would appear that PTAssembler installs its own copies anyway.]

PTAssembler
Source:
http://www.tawbaware.com/ptasmblr.htm
Instructions:
After unzipping the “zip” file, use the setup.exe program to install PTAssembler.

AutoPano
Source:
http://autopano.kolor.com/pta/pta.html
Instructions:
Download Autopano here and unzip the package in some folder. Launch PtAssembler (Warning : this tutorial is for version 2.4.2 and above) and go to the Preferences menu, tab Plugins. You should put in the autopano directory the path where you unzipped autopano. The optional command line arguments can be used to improve the result. Leave it to the default value for standard use.

Enblend
Source:
http://enblend.sourceforge.net/
Instructions:
Unzip it in a folder. Then in the dialog box, just below Autopano Parameters are located the parameters for enblend. Just Browse for the enblend.exe. Supports 16bit.

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