The Making of a Gigapixel Image
Patrick Smith is a world-renowned landscape photographer who specializes in gigapixel panoramic projects. We wanted something special for SmugMug HQ – a mind-bendingly tricky pano of San Francisco – and we thought he’d be up for the job. He pulled it off perfectly and lived to write up this guest post for us. You can see it here and cover your own walls with this amazing shot. Here’s how he did it.
It seemed like such a harmless idea at the time.
SmugMug’s Chris MacAskill wanted a print for the SmugMug headquarters that would be similar to a photo I had shown him earlier, only much bigger. He wanted a huge panoramic version of the classic view of the Golden Gate Bridge with the Transamerica building seen through the north tower. Chris was thinking of printing it somewhere in the range of 30-36 feet across at close to 240DPI. I thought it would be a decent amount of work but not a big problem – after all, multi-gigapixel photos are becoming more commonplace every day and stitching programs have improved a lot over the past few years. One recent image of London is made up of over 4,000 individual photos!
Most gigapixel images are created during daylight hours or well after dark, conditions at which the light is consistent over dozens (or hundreds) of shots. However, I wanted the entire panorama to be done during the rapidly changing light that occurs just after sunset.
After a few quick calculations, I figured that I could get the resolution Chris wanted from about 30-40 portrait photos across and a few rows high with my Canon 5D MK II and about 25% overlap between photos. I decided to rent the Canon 800mm F5.6 lens for 10 days from BorrowLenses. They were very helpful and even had a drop-off point near my house in Walnut Creek. I thought that 10 days of shooting would be plenty of time if I could choose a window of opportunity where there would be plenty of clear days with good visibility. It was November, and the California rainy season was about to begin. But with no storms in sight and a warm spell in the offing, I rented it.
I wanted to create an image that would look like a single photo taken during those few moments about 20 minutes after sunset where the softening natural light is about equal to city lights. A photograph created at this time will not have blown-out highlights but still have the glowing atmosphere of a nocturnal view. Since I needed to shoot over 30 photos per row and at least 3 rows tall, I knew that it would take several favorable days to shoot them all. This is because there are only a few minutes with good light after sunset and each exposure would take around 7-12 seconds to shoot. Also, with the 800mm lens you have to be very precise about focus, and setting the focus using the Live View feature adds even more time to each shot.
I was excited to begin. The next 10 days looked clear and warm, so off I went. The first obstacle was how to stabilize this huge lens during 10-second plus exposures when it is perched on the side of a hill exposed to strong ocean wind. The Golden Gate is the easiest place for wind to pass through the California coastal mountain range so there is a lot of it passing through. The sturdiest tripod is no match for these breezes so I had to come up with another solution.
I headed over to Home Depot and bought a 1-inch thick rounded and sanded plywood wheel that is about 18 inches in diameter. It is about the size of a very large pizza. Also I bought a plastic bucket, a short 1×4 and some thin wood shims. The idea is to place the plywood onto the bucket and then put the lens on the plywood. Then it is easy to rotate the lens right and left. The bucket is low to the ground and very stable even in high winds with the big lens on it. Also, it is easy to level the entire thing using by moving it in the dirt until your line of sight across the wheel is level with the horizon. I cut the 1×4 to a length of about 6 inches and cut notch in the middle so that the end of the lens would rest in the notch. That stops the lens from rolling around. The thin wood shims are then used to raise and lower the camera side of the lens. With this setup, you can shoot an entire row, insert or remove some shims and then shoot another row.
For the first 10 days, visibility over the bridge was perfect but it was hot and the city lights twinkled. Twinkling when viewed through 800mm of lens makes the entire frame flicker back and forth as though you are looking into a swimming pool on a windy day! During daylight it is not too bad because you can have an exposure time of 1/100 or less and things may look a bit wavy but at least they are sharp. At night, an 11-second exposure with the heat shimmering will make the entire image soft in a similar way to what you might see on a long exposure of ocean waves. Even my morning shooting suffered from atmospheric distortion. After 10 days with that magnificent lens I had nothing to show for my efforts! Needless to say I was a bit discouraged. However, I am not one to give up easily, so I borrowed a friend’s 500mm F4 and a 1.4 extender for a total of 700mm of magnification. Fortunately, he was very patient because it took about 4 extra weeks to get the images I needed.
Eventually the weather cooled, the atmosphere stabilized and the twinkling was dramatically reduced. Next, my hope was to get some mist in the atmosphere over several days to get through the entire panorama with consistent light. I made a total of about 20 trips to my spot before I had all the images I needed. All of the images used to make the final pano were captured on five of those evenings.
There were other problems during shooting besides the atmospheric distortion. First, the focus. The city is far behind the bridge, so when I was shooting the towers in front of the city I had to stop down to about F29 and focus extra carefully and do an extra long exposure. On the left side of the panorama were some foreground hills, so I had to refocus there too as well as every few shots throughout the panorama because the focus ring might get moved just a little. Most images, however, were made at F11. This allowed me to get enough depth of field to keep everything sharp. The DOF at F8 (the optimum setting) is too shallow and would cause something in each frame to be out of focus. I kept the exposure time down to 11-seconds by using an ISO of 200. There was very little noise in the final images.
The next problem is that I had to come back on successive days and pick up where I left off. So I had to arrive well before sunset to set up and practice what I was about to do. It is easy to not be perfectly aligned with a row from the day before. If you are not perfect all the way across then you don’t get enough overlap for stitching.
The other big problem is that the light was changing quickly and was different from the far left side to the far right side. This is a very wide-angle image so this is to be expected. So if you attempt a gigapixel image at dusk, study the direction of how the light fades and start shooting from the darkest areas and move towards the lightest. By the time you get to the lighter areas, they will be closer in brightness to the darker side. This way, the overall image will be more evenly lit.
I brought the images into Capture One, a RAW processing program. It has lots of settings which allow you to gain a little extra dynamic range and still have the image look natural. I collected the best images from all the shoots into one folder and carefully adjusted them for brightness and color. This went fairly smoothly, though there were a few images where I had to dig deeper. The idea is to have all the images be the same brightness.
I saved each one as a JPG because I knew the final file would be huge and I don’t have a super powerful computer! Also, I didn’t touch the JPGs until I had created a PSB file after stitching. TIFF files can only be 4gb in size and a 16-bit file would be 5gb. I ended up creating an 8-bit file but I kept it in PSB format, anyway. I did not lose any information as would be the case if I edited the JPGs directly. And JPG files have a 30,000 pixel width limit.
Originally I planned on using the highly rated Autopano stitching software. It did a great job until it reached areas where the bridge cables were in front of the bay water. As you can see in the small portion below, one cable or a bridge section looks like the next. The stitching software became confused no matter how I adjusted the settings. I auto-stitched as much as I could and then I stitched the remainder of the image (about 50%) manually in Photoshop. Fortunately there was plenty of overlap and after about 80 hours of work, the image was completely stitched.
After stitching, I went over the TIFF image carefully while viewing it at 100% magnification. I cleaned up any bad pixels or stitching errors. There was a bit of noise in some of the darker areas so I used the Photoshop noise reduction and that worked fine. Then I looked at the entire image to make sure that the entire scene looked evenly lit. A few places needed to be brightened or darkened but the adjustments were small because I was careful when creating the first set of files from the RAW files..
The combination of the 500L lens and the 1.4 II teleconverter along with close attention to focus created a final image that was very sharp. Most of the image needed no sharpening, though some areas were sharpened a bit just to get things as close to perfect as possible.
The total amount of time I spent doing recon, 20 trips to the location, and post processing was around 160 hours. Was it worth it? Yes!
If you have any any questions you can reach me at firstname.lastname@example.org .
Details about the entire panorama:
- 112 11-second exposures (they were all 11-seconds to keep the city lights constant)
- All shots were taken between 20 and 27 minutes after sunset on several nights over a 6-week period.
- The final size is (13,423h x 80,540w, 1×6 ratio)
- AutoPano stitching software to start, but 50% was hand-stitched
- Canon 5D mark II with live view set to 10x magnification to help with precise focusing
- Canon 500L F4 lens with 1.4 extender
- 3 rows of portrait oriented shots with about 35-40 on each row
- 25% overlap on each shot
- Refocus every 3rd shot with extra care on the towers and hillside to the left
- Refocus on Bridge towers to make sure that every bolt can be seen clearly
- No grad filters
- No polarizer.
- No HDR
- ISO 200 (to reduce the exposure time a bit but not too much to induce noise)
- RAW files processed with Capture One by Phase One
- TIFF files processed with Photoshop
- Tripod – 1 home depot bucket with a circular 1-inch thick plywood board rotated on top to create panoramas.