Borbin the 🐱

Imagine standing in front of a pastry display – the kind you would find in an Italian café, filled with cakes behind glass. In my part of the world it is a Kuchentheke. Not just a place to store and display cakes. It is where they take the stage.
Now picture a Tiramisu cake, viewed through a fisheye lens. The distortion, the curvature, the way the image wraps around the edges – all of it hints at the need for a projection method that can handle such transformations. This blog explores how panoramic projections like Transverse Mercator relate to real-world visual experiences, starting with this sweet example:

❌ Equirectangular Projection

The equirectangular projection maps latitude and longitude directly onto a flat grid, making it easy to process and display panoramic images. However, with wide fields of view, it introduces noticeable distortion at the top, bottom, and sides. Straight lines curve unnaturally, and objects near the poles or edges appear stretched. While it is widely used for 360° viewers and stitching software, it is not ideal for realistic close-up scenes.

❌ Cylindric Projection

Unlike the equirectangular projection, the cylindrical projection introduces more distortion, especially in vertical lines since the vertical projection is rectilinear. This makes the center of the image appear more prominent, while the sides curve away, creating a tunnel-like effect. It is useful for immersive panoramas, but in wide-angle scenes, it can exaggerate the central area and distort peripheral objects.

❌ Rectilinear Projection

The rectilinear projection keeps straight lines straight, which is useful for architectural photography. However, when applied to wide-angle panoramic images, it introduces strong stretching at the edges. Objects on the left and right sides appear unnaturally large or distorted, especially in close-up scenes like a pastry display (Kuchentheke) photographed with a fisheye lens.

✅ Transverse Mercator Projection

The classic Mercator projection is widely known for its use in navigation maps, where it preserves angles and represents lines of constant bearing as straight. The Transverse Mercator is a rotated variant, where the cylindrical surface is aligned along a central meridian instead of the equator. This makes it especially useful for mapping narrow regions that extend north–south, such as countries or cities, with minimal distortion near the central axis.

In panoramic photography, the Transverse Mercator projection can be creatively applied to emphasize the central vertical axis of an image. It helps reduce distortion toward the edges and provides a more balanced appearance in wide-angle scenes, such as standing in front of a pastry display (Kuchentheke) and capturing it with a fisheye lens. The result is a projection that keeps the center prominent while minimizing distortion on the sides.

Only a few horizontal control points are needed to achieve good alignment. For this type of optimization, at least three horizontal control points are required.
Once the optimization is complete, the areas marked by green lines in the image will be perfectly horizontal.

Only yaw, pitch, and roll angles need to be optimized.
Usually it gets you a perfect result.

More of the same scene:

From A Day in Florence, Italy
🍰

See also Panotools projection, The Balcony Panorama, Panotools projections example and Stereographic projection.

Editing equirectangular panoramic images can be challenging, especially near the zenit (top) and nadir (bottom) due to the heavy distortion in those areas. A practical solution is to convert the equirectangular image into cube faces, which represent the six sides of a cube (front, back, left, right, top, bottom). This format allows for easier and more precise editing. Once the modifications are complete, the cube faces can be reassembled into a seamless equirectangular panorama.

🖼️ Convert ➝ 🧊 Cube Faces ➝ 🖼️ Edit ➝ 🔄 Reassemble ➝ ✅ Done

This guide outlines the complete process using PTGui:

🧊 Step 1: Load the Equirectangular Image into PTGui and convert to Cube Faces

1. Open PTGui.
2. In the "Extras" menu, select the option to convert to cube faces.
3. Add the equirectangular image, set the Jpeg-Quality to 95 if you are using Jpeg, and click "Convert"

🖼️ Step 2: Edit the Cube Faces

Open the six undistorted cube face images in your preferred image editor and apply the necessary edits to the relevant face(s), such as removing a tripod from the nadir or retouching the sky in the zenit.
Save the edited images with the same filenames.

🔄 Step 3: Reassemble the Cube Faces into an Equirectangular Image

1. Open PTGui.
2. Load the six edited cube face images. You can simply drag and drop the cube face images from the explorer.

The images are automatically aligned for equirectangular output in the PTGui editor:

3. Go to the "Create Panorama" tab.
4. Choose your desired output resolution and click "Create Panorama".

Converting an equirectangular panorama into cube faces provides precise control over editing problematic areas like the nadir and zenit. PTGui simplifies this workflow, enabling seamless transitions between projections and accurate reassembly of the final panorama. This method is particularly effective for high-quality virtual tours, 360° photography, and professional post-processing tasks.

Thinking a step further, what you really need is the 15,3mm lens reported by PTGui:

Because sometimes, the best way to solve a problem … is to avoid it entirely in the first place. The 15,3mm cube face lens captures the world in exactly 90° intervals. Just six clean shots stitched with pixel-perfect seamlines, and leave the fisheye theatrics at the door.

Spokane, Washington, nestled along the Spokane River in the eastern part of the state, is known for its rich history, vibrant arts scene, and stunning natural surroundings. Named after the Spokane Tribe, 'Children of the Sun' in the Salish language, the city reflects deep indigenous roots and natural beauty.

All pictures and panoramic images are taken with 1/1000s f/5,6 ISO 100/21° f=7,5mm, unless noted otherwise.

🏥 UW

Our journey begins at the University of Washington School of Medicine's Spokane campus, where the first panorama captures the academic heart of the city.

Interactive Panorama UW

🌳 Riverfront Park

Spokane's green centerpiece, once the site of Expo '74, is now a vibrant public space full of history and movement. Bridges connect the city to Havermale Island, where some panoramas were taken. The view here spans from the upper Spokane Falls to the Pavilion, capturing the park's dynamic blend of nature, architecture, and community life.

The Centennial Sculpture on a cloudy day

And next to it, The Great Northern Clocktower

View from a nearby Hotel to the Riverfront Park

This particular panorama proved trickier than expected. Without a tripod, aligning the frames by hand made it difficult to maintain precise rotation around the nodal point, which is essential for perfect stitching. I even added an extra frame to help with stitching, but small imperfections remain. Still, the result captures the essence of the scene, even if a few pixels had a mind of their own. Sometimes, the story behind the image is part of the image itself.

Interactive Panorama Spokane Pavilion

Interactive Panorama King Cole Woodbridge

Interactive Panorama Spokane Falls Brücke

🌊 Spokane River

The Spokane River winds through the city, carving its path through stone and story alike. Along its banks, trails, bridges and parks invite exploration. The panoramic images captures the river's flow near one of its quieter bends, where reflections of sky and trees ripple across the surface.

Framed by Steel: A View Through the Bridge

River bend

Sunlit Walk Along the Water

More Pictures Along the Riverside

The World Wide Panorama contribution for the event 'Why'

A single dead tree stands between the walkway and the riverbank. Its bare branches reaching skyward in contrast to the lush greenery around it.
Why did it die? Was it disease, drought, or simply age?
Its presence adds a quiet tension to the scene, a reminder that even in places full of life and movement, stillness and decay have their place too.

Interactive Panorama Spokane River

🏢 Apartment Where We Stayed

Spokane offers a wide spectrum of hotel experiences, like a roulette wheel of hospitality. On one end, you've got places like the Ramada by Wyndham, where the décor is "early abandonment", the guests are... let's say colorful, and the rooms come with a complimentary layer of grime. On the other end, there are sleek 4-star hotels that promise luxury but sometimes deliver lukewarm service and Yelp reviews that read like cautionary tales. And in the middle? The classic 3-star American hotel, where breakfast includes a waffle machine, questionable eggs, and the lingering scent of disappointment. Choose wisely, or at least pack your sense of humor.

We were lucky. Tucked into a quiet neighborhood close to the campus, our apartment served as a perfect base for exploring the city. With morning light filtering through the windows and the scent of pine in the air, it offered a peaceful retreat.

Interactive Panorama Apartment 1

Interactive Panorama Apartment 2

✈️ Airport

Our journey ends where we first arrived, and we leave Spokane behind with memories captured in light and lines. Spokane International Airport welcomes visitors with a mix of regional charm and modern convenience. The terminal's open design and surrounding pine-dotted landscape offer a first glimpse of the Inland Northwest's character.

Interactive Panorama C7

1/80s f/5,6 ISO 200/24° f=7,5mm

1/80s f/5,6 ISO 160/23° f=7,5mm

The 737 arrives

Taxi-in

Passenger boarding bridge attaches

Start refueling and unloading

The windows facing the airfield are tinted with a subtle blue hue, and be corrected by adjusting the white balance (photos were taken using the sunlight white balance setting).

Forty minutes later, we rolled into Seattle and the Spokane chapter came to a close, pixels packed, panoramas pending, and the last bit of sunlight archived in RAW.

🌥️ Above the Clouds – To Spokane and Back

Every journey begins with a takeoff and ends with a landing, but what happens in between is often the most quietly beautiful. This segment captures both the outbound flight into Spokane and the return above the rugged silhouettes of the Cascade Mountains. From the first lift-off into layered skies to the final descent through fading light, the airborne chapters of this trip offer shifting perspectives: pine forests from above, rivers winding like thoughts, and clouds that blur the boundary between memory and motion.

All images and clips were captured using my Android phone.

SEA - GEG¹

Boarding

Taxi out from Seattle

Our turn now, with all the other Bombers lined up for their turn

Takeoff

Imagine being stuck in that one for 10 hours. It is just you, sushi, and the slow unraveling of time.

View on the Main Terminal

The South Terminal. The empty spot is S11, where the Frankfurt flight LH491 departs.

This view shows Steel Lake at the bottom and Lake Dolloff at the top, separated by Interstate 5

Landing in Spokane

GEG - SEA

Taxi out from Spokane

That view is half of Spokane Airport

Spokane Taxi Out – In Motion

Takeoff

GEG National Forest (Unofficial)

The Space Needle

Landing in Seattle

Arrived at Gate Q2

The AstrHori 6.5mm f/2 Fisheye Lens is a manual focus Circular Fisheye Lens for APS-C cameras with a 192° field of view.

Best general setting is at the 1m mark and f/5.6. This puts everything from near to infinity in focus.

The AstrHori 6.5mm Fisheye Lens fills the entire APS-C sensor with its 192° field of view, unlike the Laowa 4mm Circular Fisheye, which projects a 210° image circle that does not fully cover the frame.

AstrHori 6.5mm	Laowa 4mm

However, with only 192° of coverage, the AstrHori 6.5mm makes it difficult to capture a full 360°×180° panorama using just two images. In contrast, the Laowa 4mm performs much better in this regard thanks to its wider 210° field of view.

Example 360°×180° panorama with two pictures using the AstrHori 6.5mm Fisheye Lens:

1/800s f/5,6 ISO 100/21° f=6,5mm

Both images must be perfectly aligned using a nodal point adapter. If the camera is even slightly off-axis, parallax errors can occur, which may lead to visible stitching artifacts like this because of the missing overlap:

A 360°×180° panorama created from only two images relies solely on control points along the left and right edges. Unlike multi-image panoramas using 6+Z+N shots², there is no flexibility for adjustment in other areas of the frame.

Interactive Panorama AstrHori 6.5mm Test 1

To improve the quality of a 360°×180° panorama, three images should be taken at 120° intervals with the camera slightly tilted upward, along with an additional Nadir (bottom) shot to cover the ground area and eliminate potential shadows.

1/1000s f/5,6 ISO 100/21° f=6,5mm

The three slightly upward-tilted shots capture the sky seamlessly, while the Nadir takes care of the floor details:

But this only yields a final resolution of 8k by 4k. A two-shot fisheye panorama using the 4mm lens is 7k by 3.5k, which is already quite limited. In contrast, a full-frame fisheye panorama captured using 6+Z+N gets 16k by 8k.
All resolutions are based on a 20MP camera.

Interactive Panorama AstrHori 6.5mm Test 2

Surprisingly sharp in the corners for such an affordable lens. A clear improvement compared to the old Zenitar, which was my first fisheye lens and handled sharpness like it was optional and felt more like a Cold War relic than an optical instrument.
Not sure how the Peleng even compares, but for a circular fisheye on full-frame cameras at that time, it seems better suited for museum display than modern photography.

1/800s f/5,6 ISO 100/21° f=6,5mm

And nice sunstars:

1/800s f/5,6 ISO 100/21° f=6,5mm

Only a Circular Fisheye can capture this:

1/400s f/5,6 ISO 100/21° f=6,5mm

With the focus set to its minimum distance, the leaf is actually touching the front element of the lens. This is one of the drawbacks of this lens: you cannot make those funny fisheye closeup shots. The Laowa 4mm is much better in this regard with its extreme close focus capability.

1/800s f/5,6 ISO 100/21° f=6,5mm

More examples shot with the AstrHori 6.5mm lens on a Nikon Z30:

1/800s f/5,6 ISO 100/21° f=6,5mm

1/640s f/5,6 ISO 100/21° f=6,5mm

1/640s f/5,6 ISO 100/21° f=6,5mm

1/800s f/5,6 ISO 100/21° f=6,5mm

1/800s f/5,6 ISO 100/21° f=6,5mm

1/800s f/5,6 ISO 100/21° f=6,5mm

1/1000s f/5,6 ISO 100/21° f=6,5mm

1/1000s f/5,6 ISO 100/21° f=6,5mm

1/1000s f/5,6 ISO 100/21° f=6,5mm

1/1000s f/5,6 ISO 100/21° f=6,5mm

Summary

✅ AstrHori 6.5mm: Best for general fisheye photography, great sharpness, sunstars, and APS-C coverage.
✅ Laowa 4mm: Best for minimal-shot 360°×180° panoramas and creative close-up fisheye fun.
✅ TTArtisan 7.5mm: Best for general 360°×180° panoramas.
❌ AstrHori 6.5mm: Not ideal for close-ups or minimal-shot panoramas.
❌ Laowa 4mm: Weaker in flare resistance.
❌ TTArtisan 7.5mm: Beware the lens cap: it has a mind of its own and occasionally makes a break for freedom. Even with a fix in place. A true escape artist.

See also
TTArtisan 7.5mm f/2.0 Fisheye Lens
Laowa 4mm f/2.8 Fisheye Lens

It is finals week for spring quarter at the University of Washington (UW), and graduation celebrations are just beginning. The weather is good, and with the UW campus full of open spaces and interesting buildings, it is the right time for panoramas and for capturing every pixel from zenit to nadir.

Overview

Campus Landmarks

• Red Square
• The Quad
• Statue of George Washington
• Drumheller Fountain

Academic Buildings

• Suzzallo Library
• School of Art and School of Music
• School of Art
• Denny Hall
• Smith Hall and Miller Hall
• Communications Building

Bridges & Pathways

• Bridge to Henry Art Gallery
• Rainier Vista
• Rainier Vista Northeast Bridge
• Bridge to Husky Stadium

Panoramas

All panoramas photographed that day were taken without a tripod using a Nikon Z30 with a 7.5mm Fisheye Lens. In the library, this was necessary anyway, since photography is allowed but tripods are not permitted in the UW Libraries.

Red Square

This panorama captures Red Square, a central open space on the University of Washington campus known for its iconic views and architectural surroundings.

Interactive Panorama Red Square

1/1000s f/5,6 ISO 100/21° f=7,5mm

Suzzallo Library

Suzzallo Library stands as one of the University of Washington's most iconic buildings, with its grand Gothic architecture lending a timeless presence to the campus landscape.

Suzzallo Library Reading Room

Interactive Panorama Suzzallo Library 1

1/125 f/5,6 ISO 320/26° f=7,5mm

Interactive Panorama Suzzallo Library 2

1/125 f/5,6 ISO 320/26° f=7,5mm

Interactive Panorama Suzzallo Library 3

1/125 f/5,6 ISO 320/26° f=7,5mm

Suzzallo Library Treppenaufgang 1x3

1/125s f/5,6 ISO 1320/26° f=7,5mm

Circular Fisheye projection

Equirectangular projection

3 + up + down

View from Red Square

1/1000s f/5,6 ISO 100/21° f=7,5mm

Equirectangular projection

Rectilinear projection

Statue of George Washington

The Statue of George Washington stands at the west end of Red Square, a longstanding symbol of the university's heritage and a familiar landmark for students and visitors alike.

Interactive Panorama Statue of George Washington

1/1000s f/5,6 ISO 100/21° f=7,5mm

Bridge to Henry Art Gallery

The Suzzallo Library and the Statue of George Washington are partially visible in the background, adding a subtle sense of place and history to the scene.

Interactive Panorama Bridge to Henry Art Gallery

1/1000s f/5,6 ISO 100/21° f=7,5mm

The Quad

The Quad is a beloved green space on campus, especially known for its breathtaking cherry blossoms each spring and its peaceful, tree-lined walkways year-round.

Interactive Panorama The Quad 1

1/1000s f/5,6 ISO 100/21° f=7,5mm

It is probably called The Quad because it was easier than explaining That Big Square Where Everyone Takes Cherry Blossom Pics. Besides, calling it The Quadrangle sounds like a spell Hermione would cast right before finals.

Interactive Panorama The Quad 2

1/1000s f/5,6 ISO 100/21° f=7,5mm

Airplane spotted cruising at tree level. Must be a scenic route.

Smith Hall and Miller Hall

Smith Hall and Miller Hall stand side by side along the edge of the Quad, their classic collegiate architecture framing the space with a sense of tradition and academic purpose.

Interactive Panorama Smith Hall and Miller Hall

1/1000s f/5,6 ISO 100/21° f=7,5mm

Denny Hall

Denny Hall, the oldest building on campus, stands with timeless elegance, its Romanesque architecture marking the historic beginnings of the University of Washington.

Interactive Panorama Denny Hall

1/1000s f/5,6 ISO 100/21° f=7,5mm

Rectilinear projection from the panorama

School of Art and School of Music

The School of Art and the School of Music sit near the edge of campus, where creativity and performance shape a vibrant cultural presence within the university's academic landscape.

Interactive Panorama School of Art and School of Music

1/800s f/5,6 ISO 100/21° f=7,5mm

Avoiding Stitching Artifacts with Masking

In panoramic imaging, particularly in architectural or urban settings, a common source of stitching artifacts occurs when prominent structures such as building façades are captured in separate frames rather than as a whole within a single exposure. This segmented capture approach increases the risk of misalignment during the stitching process, often resulting in visible seam lines that disrupt the continuity and geometry of key architectural features.
In this panorama, the two building façades are each captured in separate frames but have been (green) masked to ensure that no seam line intersects the primary architectural elements, preserving structural integrity in the final composite.

School of Art

The School of Art combines creativity and academic depth, giving students a place to study classic forms like drawing, painting, and sculpture.

Interactive Panorama School of Art

1/200s f/5,6 ISO 250/25° f=7,5mm

Communications Building

The Communications Building houses the university's journalism and communication programs, offering students a dynamic space to explore media, storytelling, and public discourse.

Interactive Panorama Communications Building

1/160s f/5,6 ISO 100/21° f=7,5mm

Drumheller Fountain

Drumheller Fountain sits at the center of Rainier Vista, offering a stunning reflection of Mount Rainier on clear days and serving as a scenic focal point surrounded by some of the campus's most iconic buildings.

1/1000s f/5,6 ISO 100/21° f=7,5mm

Equirectangular projection

Stereographic projection

Interactive Panorama Drumheller Fountain 1

1/1000s f/5,6 ISO 100/21° f=7,5mm

Interactive Panorama Drumheller Fountain 2

1/1000s f/5,6 ISO 100/21° f=7,5mm

Rainier Vista

Rainier Vista is a grand, tree-lined axis that stretches from Red Square to Drumheller Fountain, offering a sightline to Mount Rainier on clear days and serving as one of the campus's most iconic visual corridors.

Interactive Panorama Rainier Vista

1/1000s f/5,6 ISO 100/21° f=7,5mm

Rainier Vista Northeast Bridge

The Rainier Vista Northeast Bridge spans a key pedestrian route near the end of the vista, offering elevated views of Drumheller Fountain and the surrounding landscape while connecting key parts of the campus with ease and elegance.

Interactive Panorama Rainier Vista Northeast Bridge

1/1000s f/5,6 ISO 100/21° f=7,5mm

Bridge to Husky Stadium

The bridge to Husky Stadium provides a vital pedestrian link between the main campus and the athletic complex, guiding fans and students alike across Montlake Boulevard with sweeping views of Union Bay and the stadium's iconic silhouette.

Interactive Panorama Bridge to Husky Stadium

1/1000s f/5,6 ISO 100/21° f=7,5mm

UW Panorama Map³

And here, the panoramic journey ends for today

1/200s f/5,6 ISO 100/21° f=7,5mm