Last Spring two FARO employees Jeff Squibbs and Matthew Daly and myself took a FARO Focus3D laser on a hike up to Delicate Arch located just outside Moab Utah in Arches National Park. The goal was to capture the world famous natural sandstone landmark in an accurate 3D point cloud using a laser scanner.

Why capture the Delicate Arch in 3D, because we can. Capturing the Arch is not only fun, but demonstrates there are no limits to the practical use of Reality Capture techniques and applications to document existing objects in 3D.

From my blog post prior to the adventure To Capture Delicate Arch in 3D

In this photo you can see the scale of Delicate Arch as many people are climbing around it. The arch is about 65 feet (20 meters) tall and sits on the edge of a slope that turns to a cliff a bit further down.

Sandstone arches like Delicate Arch are fragile structures made up of layers of Entrada Sandstone and by their very nature are changing all the time with weather and erosion which not only creates them but results in their demise over time. Just a couple years ago nearby Wall Arch lost its battle with gravity and the elements and was reduced to a pile of sandstone boulders.

Going from analog to a digital - then down to a four inch plastic arch.

The Team from left to right Matthew Daly of FARO, Jeff Squibbs of FARO, and me Shaan Hurley of Autodesk.

We received the written permission of the National Park Service before even considering this project so as not impacting the location or visitors. With the FOCUS 3D laser scanning unit being so small and portable were easily able to capture several scans without impacting any of the other visitors to the site that day. We did get several people inquiring “what kind of cool new camera is that.”

In order to capture the entire arch we had to climb like all over the visible sight lines which resulted in capturing over 95% of all surfaces. The only surface not able to be completely captured by laser was the top which was flat except a small bush growing on it.

For the areas we could not scan using the laser, I was able to capture photos of the surfaces and generate 3D mesh for the missing surfaces using Autodesk 123D Catch which takes photos captured with a digital camera and converts them to a 3D model.

The 3D Model created from photos using Autodesk 123D Catch

The 123D Catch model imported into 3ds Max

Using both the data from the laser scanner captured point clouds and some surface mesh from 123D Catch we re-constructed an accurate 3D digital model of Delicate Arch.

Here are some images of the point cloud captured. It is comprised of billions of points in 3D x,y,z space. We scanned much of the bowl formation where the arch is.

You can see closer detail of the point cloud here with intensity values coloring it red-orange.

Getting the point cloud from a laser to a surface watertight meshed model is no easy feat especially with an organic structure as faceted as the sandstone arch and currently requires a great deal of work and various software. Hopefully in the future this becomes an easy process.

Here is the meshed model in 3ds Max created from the point cloud data. This is one highly detailed and accurate model.

Using a consumer 3D printer a MakerBot I decided to take this huge digital model and reduce it to a small 4” model which could be printed in 3D as a plastic replica of the original.

So I sent the STL of Delicate Arch to my MakerBot and in 90 minutes had my Delicate Arch in red ABS plastic which I can proudly place on my desk or show to people explaining the story taking this huge natural landmark and reducing it to the scale that I can carry in my hand. It is captured forever in time while the original continues to shift and change but hopefully lasts well into the future for everyone to enjoy. I will be making available the STL file of the scaled down Delicate Arch for others to 3D print their own. I am not including the monster detail model or point clouds just the STL file for the small 4 inch arch. The location of the STL model will most likely be in the Thingiverse library.

Below is the resulting four inch 3D print in red ABS plastic, the same materials Legos are made of.

I can’t wait to drop some miniature arches and the point cloud data set off to the National Park Service. They will be surprised as most every other Delicate Arch model in existence was based on an artist sculpture, not capturing the real geometry digitally. I am also giving many of these small arches to others including all those involved such as FARO’s Jeff and Matt who were key in this experiment in reality capture.

You may be wondering “but I don’t have a laser but would like to capture existing objects in 3D and print them as well.” That is not a problem as you too can do this using Autodesk 123D Catch then working on the mesh in the free Autodesk MeshMixer then export a standard STL format file for your 3D printer or you can use an online 3D print service like Shapeways where you could also print on several other materials.

Update: The Arch is now on Thingiverse http://www.thingiverse.com/thing:18224

Cheers,
Shaan

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