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colorful tiled image showing 4 orchid plants with blooms

Capturing Nature’s Masterpiece: A 3D Scanning Adventure

By Katie Wolfe and Jon Blundell on Tue, 01/30/2024 - 16:47

In the summer of 2023, the Digitization Program Office and Smithsonian Gardens collaborated on a project to 3D scan several orchids in support of The Future of Orchids exhibition. The goal was to create 3D printable files for the artist Phaan Howng to use in commissioned works that would be featured in the exhibit, and to tell the stories of selected orchid specimens through guided tours using the Smithsonian’s 3D viewer.

Explore the 3D collection here!

Before this project, the only plant in the Smithsonian’s 3D collection was a model created from a microCT scan conducted in 2014.

While impressive in its technical detail, this 3D scanning method couldn't capture one of the most enchanting aspects of orchids: their vibrant colors and delicate, painterly patterns. The biodiversity of the Smithsonian Garden’s orchid collection also makes it important to capture color, since a way of distinguishing between varieties is through coloring. So for the 2023 project, our team agreed to take on the challenge of capturing not only the 3D geometry of the orchids, but the color as well.

"On the left is a machine with a door open showing a conical cup holding a flower clamped in the middle. On the right is a close up view of the flower bloom nestled into the cone cup of paper."

These photographs show what the microCT scanning set up looked like for the Embreea orchid capture. To ensure the petals did not move during scanning, a paper collar was wrapped around the bloom.

Now would be a good time to mention that scanning orchids is difficult, to say the least. Orchids are living things that change shape throughout the day as they react to the environment, such as wilting in heat or swaying in a light breeze. Their blooms can be paper thin and have elements finer than a whisker. These characteristics make it difficult to capture them in 3D, since our methods require the subject to be still through the duration of scanning for accurate results.

Creating an Orchid “Still Life”

With botanical specimens so delicate and prone to movement, we had to create a 3D scanning environment with minimal airflow and vibrations to avoid disturbing the plants. In our testing leading up to the capture, we found that the breeze coming from air-conditioning vents caused the petals to flutter. Even people walking by swiftly in the room caused enough wind to move the flowers and leaves. While there were some things we couldn’t control, we did our best to keep our body movements slow and (unfortunately for us in the summertime) the air-conditioning turned off. Over a small speaker, we even played music composed for plants, and channeled the slow and peaceful melodies.

Clear and Present Support

To further stabilize the orchids, wherever we could, our team used clear plastic rods to help support the leaves, flowers, and stems of the orchids.

The long stems of the Psychopsis orchid were able to stay in one place by weaving flexible, thin acrylic rods to quarter meter scale bars. Not only did the scale bars provide accurate measurements the 3D scene could be scaled too, but it helped create more feature points to help in the photogrammetry software’s alignment phase.

The rods helped provide enough support to let the plants rest on top of or in between, without being too obstructive to the camera’s view or adding color that would be reflected onto the plant.

"A photograph of a person in a grey shirt and red cap kneeling at the base of a tripod with a potted orchid placed on top. The person is adjusting supports the clear plastic rods stabilizing the orchid."

Each day of capture, Caroline Stokes would get the orchids in just the right position for 3D scanning, and ensured they looked their best. Her patience and tender care with the orchids helped us achieve fantastic results!

Caroline Stokes, a horticulturist with the Smithsonian Gardens team, spent time each morning carefully placing rods in areas that would support the botanical specimen of the day, without putting too much pressure on the plant.

Twice as Nice: Doubling up on capture

For a project as difficult as this one, our team will often deploy a variety of scanning techniques to ensure we have captured complete 3D data to the best of our abilities. 

"A screenshot from photogrammetry software showing a 3D model of a potted plant surrounded by a circle of thumbnail images."

Although this screenshot only shows a fraction of the images used to create this 3D model, it helps visualize how photogrammetry software triangulates image placement during the alignment phase, which is the first step in the 3D reconstruction process. To make an object 3D, you truly need to capture it from all possible viewing angles!

Our primary capture method was photogrammetry, which is a technique that extracts 3D data from multiple overlapping images. For each orchid, we took hundreds to thousands of photographs at varying angles and heights to feed the photogrammetry software. Since the 3D model is created using photographs, the color information of the subject is also recorded and used to create a color map on top of the 3D surface.

"A person is standing to the left holding a camera to their face pointed up to the right at a potted plant with purple flowers."

Joseph Campbell performing photogrammetry capture of a Vanda coerulea orchid.

In addition to taking photographs, whenever time allowed, we used a laser line scanner to gather rich geometry details of the orchids. Through our partnership with FARO, we have a laser line probe that attaches to an articulating arm that we use for high accuracy and resolution geometry capture. The probe measures how a laser line deforms over a surface and can translate that information into 3D data. Under the right conditions, the laser line probe can capture 30 microns of detail!

"A person is standing to the right grasping the handle of a mechanical arm pointed at a purple flower bloom to the left with a blue laser line coming from the arm and projecting onto the surface of the flower’s petal. "

Katie Wolfe performing laser capture of a Vanda coerulea orchid bloom.

Separate from the full body orchid capture, we fully 3D scanned cut flowers from a selection of the species. Using a ring flash camera rig for photogrammetry and the laser line probe, we were able to achieve robust, detailed captures of these blooms.

"A hand holding a yellow scoop shaped piece of an orchid bloom."

The interior pouch of the Phragmipedium x richteri bloom.

In some cases, we selectively plucked the petals of these cut flowers to reveal their interior and captured even more information that would otherwise be hidden from view.

A Blooming Success

After a couple weeks on site and 2.5 terabytes of raw data later, we packed up our gear and bid our Gardens colleagues farewell. Our team now had the task of using the capture information to create 3D models that hopefully would convey the beauty of the original specimens. Despite some of the difficulties this project posed for 3D digitization, our careful approach and hours of post processing yielded some stunning results!

"A grid collage of four colorful renders of 3D orchid models."

Colorful renders of some of the orchid 3D models.

We enjoyed working with the Gardens team and can’t wait to see how the CC0 data gets used by the public. Their team authored some great content about the orchids in their 3D scenes, which we encourage you to check out! We hope you appreciate learning about these plants as much as we have by talking with the Gardens staff throughout the 3D digitization process.   

If you’d like to learn more about the Smithsonian Gardens The Future of Orchids exhibit, and how artist Phaan Howng used some of our team’s 3D scans of orchids to create her sculptures, check out the exhibit at the Kogod Courtyard running from January 27 - April 28, 2024. 
 
If you like to explore the orchids in 3D, drop some in your living room using augmented reality, or create your own 3D prints see: https://3d.si.edu/collections/future-of-orchids