Pbarnhardt is correct. Here are some images that show some of the process I went through.
Essentially, I first took a **** ton of references. Throughout the project I was constantly going back into the game and getting more references from different angles. I ended up with about 400 images:
I spent a good while measuring out the room and guesstimating its size by using Isaac’s step-length and his height (which proved quite difficult as he has terrible posture in game haha). I blocked out the room in Unreal and began creating the pieces of the level that repeated the most and were the most influential to the shape and size of the space (most notably the large open windows). Here are some early shots of the project:
From there I essentially just went at it, filling in the various architecture/props one by one. I tried to recreate things as closely as possible to original game. Here and there I would make some changes/edits to the appearance or scale of things as I saw fit. Other times I just made mistakes and didn’t get them to look quite right haha. Here are some comparisons:
The models I created in Maya. Luckily the Ishimura has a huge amount of repeating shapes and patterns, so I was often able to re-purpose many of things I’d created into other objects. That being said, this process still took months. There were so many little details 0_o
The textures I created in photoshop and crazybump. Almost all of the metal pieces of the ship (the walls, railings, floor, etc…) I hand painted myself trying to replicate the lines and patterns I was seeing in the reference images:
I then reused many of these textures on smaller, more insignificant objects by finagling their UV’s around. For other objects, I created the textures with a combination of photos from the internet and hand painted texturing:

I tried to avoid using anything I found without significantly altering it in some way. The only textures I didn’t change at all are the propaganda posters from the original game (which I found in this old article: A week of Dead Space: The REAL signs from the Ishimura – Destructoid). Also some of the holographic UI symbols/elements are from things I found/Photoshop brush sets.
So yeah, I hope that was helpful/answers your question! Let me know if you have any more