Ruby E Photogrammetry Model (including engine room)

[beldridg]

The Ruby E is a great wreck in San Diego in relatively shallow water (85 fsw to the sand) with a fun and interesting history. I did a few dives to build a photogrammetry model but then also decided to include the engine room and cargo area in the model. It is my first attempt at including interior spaces into a model. I'm still working on the best way to "show" interior spaces.

The post along with photos and a link to the model are at the link below. If you click on the link for the model, you can actually navigate into the engine room and see the dual six cylinder engines!

Ruby E (San Diego –85 fsw)

Background The Ruby E was the second vessel intentionally sunk off of Mission Beach, San Diego as part of “wreck alley.” She was built in 1934 and sank on June 18, 1989 so she has been …

wreckedinmyrevo.com

Here is a direct link to the model:

Ruby E Wreck (mobile / low res version) - 3D model by Brett Eldridge (@beldridg)

The Ruby E was previously a Coast Guard Cutter that was sold to the private sector and then finally sank in “Wreck Alley” in San Diego. Note that this model includes interior spaces in the engine room and cargo area to the aft of the engine room. You can “peek in” and navigate into those...

sketchfab.com

Below is a screen capture looking into the engine room:

Regards,

- brett

 

[falconguy]

WOW this is awesome. The Ruby E was sunk the day I was born and was the first wreck I was able to dive once I got my OW. Thank you for doing this, really cool!

Landon

 

[Akimbo]

Very nice work. Can you tell us a little more about the process?

1. About how many images dives were required?
2. Are images still or video?
3. You mentioned difficulty aligning images between dives, is that a common problem? What about images from different cameras and/or on different days?
4. Is there an option to bring up the images used to generate the model during the editing process?

 

[scubadada]

Hi @beldridg

Thanks for posting the Ruby E, brought back good memories of my 6 dives on her from 2007 to 2012, often as a 2nd dive after the Yukon. The wheelhouse was still in place when I visited.

You've recently covered 3 of my old favorites, the Yukon, the Hogan, and the Ruby E. You briefly covered the P-38 off Torrey Pines in your blog in a post from the summer of 2020.

Take care, good diving,

Craig

 

[beldridg]

Very nice work. Can you tell us a little more about the process?

1. About how many images dives were required?
2. Are images still or video?
3. You mentioned difficulty aligning images between dives, is that a common problem? What about images from different cameras and/or on different days?
4. Is there an option to bring up the images used to generate the model during the editing process?

Thanks!

I wish there were "simpler" answers but, like most things, it is all a tradeoff. One of the reasons I'm teaching a workshop is to help "jumpstart" some people into photogrammetry. I'll try to provide some answers to the questions:

1. For this model, if I don't consider the inside spaces, it would be two dives and about 2,500 images. The big tradeoff comes in details vs more photos. Assuming you had crystal clear waters, you could probably get away with something like 250-500 photos to show the entire wreck. However, you wouldn't get the level of detail. The more detail you want, the closer you have to get which means the more photos you have to take. SoCal also has the added challenge of not-so-great vis on most dives so you have to get closer anyway which means more photos.

I tend to shoot way more photos then needed knowing that I can use the "estimate quality" function in Metashape and throw out low quality photos AND I can use the "reduce photos" function to reduce the photos used for the model construction and texture (if I want).

2. I use still images. There is an option in Metashape to input a video and it will pull out frames and then you can align them. I have only tried it once or twice and what I have found is that the frames are not always completely focussed and the model tends to be a bit blurry). Admittedly, I haven't spent a bunch of time working with video.

3. I'm not sure if it is a common problem. To be honest, I don't know a ton of people building models of large underwater wrecks with the level of detail. I know Becky Kagan Schott is and I talk with her about photogrammetry, but I haven't asked her about her multiple dive techniques. I think the conditions in SoCal and the need to get closer to the structure complicates it.

One thing I can definitely tell you is that if you plan to shoot something across multiple dives, you should use the same camera / lens / focal length / lighting, etc. I think the Metashape manual even mentions it.

4. The short answer is "yes" but there is a much longer answer depending upon what you are trying to do with the selection. Here is a screenshot that shows which cameras were used on a specific area in a model. I've selected one photo on the list on the left and you can see where the software has placed it during alignment.

The "long answer" is much longer.

Related to that, I just found a new option that can be used when selecting areas to delete that will only select "visible" sections. I think this will help when I try to "strip away" a hull or deck to show the inside structure. Normally, when you select an area to delete, it slices through the entire model.

One of my research areas right now is the "best" way to show an inside space within the context of an overall model. In the example below, I have selected the port side of the hull and deleted it in a "cutaway" fashion to show the inside of the Ruby E.

I plan to put out a detailed post sometime in the New Year that compares different ideas / methods for depicting the insides of wrecks.

This is why I refer to photogrammetry as both "an art" and "a science." For simple models, it is more science. For complex models, it is definitely an art that has a lot of nuance.

Regards,

- brett

 

[beldridg]

Hi @beldridg

Thanks for posting the Ruby E, brought back good memories of my 6 dives on her from 2007 to 2012, often as a 2nd dive after the Yukon. The wheelhouse was still in place when I visited.

You've recently covered 3 of my old favorites, the Yukon, the Hogan, and the Ruby E. You briefly covered the P-38 off Torrey Pines in your blog in a post from the summer of 2020.

Take care, good diving,

Craig

Thanks, Craig! I've got a few more surprises coming this week before my annual "Top 10" for 2022 post.

- brett

 

[Cthippo]

Video I did on the Thetis Class, of which the Ruby E, nee USS Cyane, is one

 

[Jeff_O]

Nice work! I was looking to see the prop, which I did not see. Did it come with one before they purposely sank the Ruby E. I dove wreak alley and I know I saw a huge 3 blade prop at somewhere around 120 ft depth. The other two wreaks there when we dove were the El Ray and the Yukon. So maybe was one of the others.

Video I did on the Thetis Class, of which the Ruby E, nee USS Cyane, is one

 

[Johnoly]

If you click on the link for the model, you can actually navigate into the engine room and see the dual six cylinder engines!

WOW,,,that came out really nice and clear. It will be a great source of information for divers who want to make a dive plan to get the very most out of their bottom time. Excellent model !!

 

[beldridg]

Nice work! I was looking to see the prop, which I did not see. Did it come with one before they purposely sank the Ruby E. I dove wreak alley and I know I saw a huge 3 blade prop at somewhere around 120 ft depth. The other two wreaks there when we dove were the El Ray and the Yukon. So maybe was one of the others.

Thanks!

There is a prop on the RubyE on the port side of the ship. There might also be one on the starboard side (I'm assuming so) but it is buried in the sand due to the list. Here is a picture of the prop from my blog post:

It is also visible in the on-line photogrammetry model:

However, it is at about 85-ish feet deep and nowhere near 120 feet. The prop on the Yukon is actually a "training prop" and is surrounded by a shroud. It is at about 105 feet deep so closer to what you remember. I built a photogrammetry model of the Yukon prop a couple years ago as an exercise when I was learning the skill.

Here is a picture (not a great one, just a picture for a model) I recently took when working on my model of the Yukon along with a screen capture of the model:

The max depth of the El Rey is something like 75 feet so I don't think it would be that wreck. I've actually never dove it so I'm not sure if the prop is there or, if it is, what it looks like.

Regards,

- brett