Holden Observatory

3D scanning a full size building

The very first time I saw ordinary television working, I was struck by a tremendous idea. "Look here!" I shouted. "If these people can break up a photograph into millions of pieces and send the pieces whizzing through the air and then put them together again at the other end, why can't I do the same thing with a bar of chocolate?

Why can't I send a real bar of chocolate whizzing through the air in tiny pieces and then put the pieces together at the other end, all ready to be eaten?"

-Willy Wonka, Chocolatier                                       


After scanning a few people, some art, and even my cat I was approached by Arland Whitfield and his drone with the idea to scan something BIG.

The building we decided on was Holden Observatory on Syracuse University's campus, one of the oldest buildings in the area and at a little over 2 stories tall it was the perfect sized challenge to try and bite off.

Instead of attaching a depth sensor to the drone we decided to take the route of photogrammetry, which involves photographing the object from all different angles to later calculate the size and shape of the subject.

Essentially the software will attempt to retrace your steps as the photographer and from the photos recreate the objects that were front of you. The easier it is for the software to follow and understand the path of your camera and the objects you were looking at, the better the result of the model.

isaac on left, Arland on right in a candid photo between flights
Photogrammetry - 'photo' - light | 'gram' - drawing | 'metry' - measurement


From my experiments scanning regular sized objects, I knew there were 3 basic angles we needed to capture in order to get the scan.
  1. Low and angled up
  2. High and angled down
  3. Directly above and straight down


Using that process we ended up with a lot of photos, over 400 in total! Here is a sampling of a few of the different angles we were able to photograph.

Software Point of View

After looking at all of the photos we took we narrowed it down to a hardy 274 photos to upload. After uploading it takes awhile for everything to get sorted, analyzed, torn apart and finally pieced back together together.

After we click go the software takes all of those photos, finding common and identifiable elements in each stitches together the objects in the scene.

This photo shows how the software deconstructs the different pieces of the photo before stitching them together. If you look closely you can see different parts of the Observatory!


Success! A 3d Model

After all that and a little bit of manual clean up we get the 3d model you see below!
Click on it to pan, zoom and spin around the digital Holden Observatory

3D Printed Observatory

After we have our model cleaned up and ready to go we sent it to our 3d printer to be produced in three dimensions. If you would like to learn more about 3d printing , how it works and how you can get involved check out my book The Book on 3D Printing.

The Holden Observatory was printed in ABS Filament at a 130 micron layer height and hand painted with acrylic painted.

Historical Facts

Building Announced: Fall, 1886
Construction Completed: September, 1887
Dedicated: November 18, 1887
Dedication Speaker: Dr. Simon Newcomb, noted astronomer
Named For: Charles Demarest Holden, Class of 1877
Materials: Onondaga Limestone with lead-covered dome
Architect: Archimedes Russell
Size: 30 feet by 32 feet with 30-foot high tower
Funding: Erastus F. Holden, coal merchant and SU trustee
Original Location: south side of hill west of Hall of Languages
1991 Relocation: 190 feet southwest of original location

The second building on Syracuse University's campus, the observatory was named in memory of the donor's son, Charles Demerest Holden (d. 1883). When completed, the observatory held an eight inch Alvin Clark telescope, 3 inch reversible transit, a comet seeker, chronograph and chronometer. The telescope was housed in a tower with a rotating dome.

Historical Information from http://archives.syr.edu/buildings/holden.html