HMCS Yukon Guns Photogrammetry Model (San Diego, 105 fsw)

I won’t spend time describing the Yukon wreck since it is probably the most famous wreck in California.

I’ve dived it a number of times and there are a lot of cool features. Probably the most well known and most often photographed are the guns on the forward section of the ship. They are massive.

I recently did a dive on the Yukon with the express purpose of working on photogrammetry models. I picked two subjects: the guns and the propeller. More on the propeller in another post.

The guns are a tricky subject to photograph due to their length and the fact that the visibility is usually not great on the Yukon. So, you are trying to do a wide angle photograph to get all of the guns and the turret in the frame and the visibility isn’t great.

Below is a link to the model, a photo and the details about the challenges building the model.

Yukon guns
Low Res Model on Sketchfab

Some Trivia about those guns

When I showed the initial model to Tyler, he said to me “did you know that those aren’t the real gun barrels” and that “they are light posts.”

Huh?!

Well, it is absolutely true! According to the article in California Diving news:

“The forward guns look real enough but the barrels were replaced before sinking with dummy pipes to simulate the guns. “

California Diving News

Steve Lawson also provided more context in an email exchange:

“When the ship was decommissioned, the barrels were removed (NB: pictures below). It is unclear whether they were repurposed or whether there was a security concern having the real barrels on the wreck. Prior to the sinking, one of the volunteers cleaning up the ship noticed the missing guns. He was employed by CalTrans and saw a resemblance to the light poles that they replaced due to damage or wear and tear. He was able to get two scrapped light poles and had them cut to the right length and welded in place. If you take a close look at the end of the barrels, they are very thin compared to the ~ 2 inches of thickness of a heavy duty barrel.”

Summary of an email with Steve Lawson

I found a couple pictures of the guns without the fake barrels yet attached:

Building the model

I knew that the model would be challenging to build – primarily due to the sharp angles at the of the gun barrels. Anytime you have structures suspended in “mid-water” and with sharp angles and ends, it requires a LOT of pictures to get the photos to align.

I took a total of 359 pictures. Most of the aligned but it took a few tries to get them all correct. The total processing time was about 90 minutes to align the photos with “medium” accuracy.

Sparse model after alignment

I then built the dense cloud with medium quality and, unfortunately, did not get the end of the guns to get modeled. The depth maps and the dense cloud took about two hours to build

Medium quality dense cloud model (note that the gun barrels are clipped)

I built a textured model based on the medium cloud model but it obviously didn’t include the end of the guns. I then decided to see what a “high quality” model would end up looking like. I kicked off the process before going to bed one night and expected it to be completed the next morning. Boy, was I wrong!

Building the depth maps and the the dense cloud model took 11 hours!

However, the model turned out to include the full length of the guns so that worked out well.

High Quality Dense Cloud

I then built the textured model which took about 40 minutes.

High Quality Textured Model

Here are some additional screenshots and a link to the online model

References

California Diving News

Divebums article with photos

One thought on “HMCS Yukon Guns Photogrammetry Model (San Diego, 105 fsw)

  1. Cool. Finally got out over the weekend. I looked at a target off Oceanside that turned out to be the chassis of an old military truck. Vis was poor and arm’s length.

    Steve

    Like

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