Blueprint Appreciation Post

Technical drawings are the thing that made this Hogwarts project possible, full stop. I don’t remember which of these was the correct order of events:

  1. I stumbled upon some blueprints online and thought, Wow, I could actually do a 3D model investigating the changes!
  2. I thought, Wow, I’d really like to do a 3D model investigating the changes! and subsequently found some blueprints online.

But either way, I don’t think I ever would have started this thing without some floor plans to guide me.


For the first film, I’ve got two different scans of a single plan of the miniature. One is a high-res B&W scan; the other has much lower resolution and a tighter crop, but it’s in color. Interestingly, their perspectives don’t match, suggesting that one or both of them may have actually originated as photos, not scans. But regardless, here I’ve tried to align them together, applying the low-res color data to the high-res scan. I’ve also rotated it (to match the plans for the other films) and corrected the perspective.

I have a few observations. First of all, this is evidently the fourth revision, dated January 14th, 2001, but there were likely other revisions after this. I say that because this plan is not completely accurate. Flaws I’ve noticed:

  • The Great Hall balcony has the wrong shape – the corners are square and it doesn’t wrap around the north side of the structure.
  • The training grounds tower doesn’t indicate the circle tower where it meets the Durham courtyard structures.
  • The quad interior has the wrong dimensions.
  • The walkway along the east side of the quad exterior appears to have a single level, and the elevation is marked as (I believe) 220′. This is the same level as the adjacent stone bridge. The final design for the first film moves the walkway lower down, with the part nearest the bridge even lower still. This also calls into question the accuracy of the area north of the quad, for which I sadly have no adequate photo reference.

Still, this is an absolutely invaluable look at the original castle.


Sadly, I have no floor plans for the miniature in the second or third films. I very much appreciate Warner Bros. posting these Prisoner of Azkaban elevations at the Studio Tour in London, though:

These cover many of the main changes to the castle in that film, and they were the reason I started my project with the Azkaban castle.


Goblet of Fire is an interesting one. I do have one partial floor plan, but the whole Great Hall/boathouse area is all wrong, as is the quad interior. I suspect that one wasn’t the final revision either.

As you can see, this consists of two scans or photos overlaid on top of each other. This composite I did not do – this is how the image was posted by user “decat” at the RPF.

This drawing provides evidence for the quad cloisters still existing in POA. Presumably, they were still part of that version, and at the time this drawing was created, they simply hadn’t yet decided to raise the quad, add the new arch, remove the cloister and fountain, etc. This is also the only plan I have of the training grounds tower from the COS redesign, and of the adjacent pathway that would eventually change in HBP.


I have no drawings of the miniature from OOTP. Fortunately, not much changed, and the changes that did occur will be easy enough to replicate with help from photogrammetry measurements.


The final HBP floor plan was actually released by Warner Bros. in the book Harry Potter: Page to Screen. It’s a two-page spread, which is wonderful for being able to read all the writing, but it does put an unfortunate seam right in the middle:

Still, it’s a fabulously detailed view of a critical production document and I’m grateful for it. I’m not aware of any inaccuracies here.

The same can almost be said of the earlier version on display at the Studio Tour:

The odd tapering crop is the result of perspective correction, since the original photo was taken at an angle. Note the lack of even the small HBP training grounds tower, the dotted outline of the old DADA tower to be removed, and the more detailed plan of the new astronomy tower.

If that’s not enough for you, though, don’t worry – when it comes to the astronomy tower, MTV News has your back! (Of all sites!)

I haven’t built the astronomy tower yet as of this writing, but this drawing is going to make it a cinch.


The main DH floor plan has also been officially released, albeit with some photo overlays that obscure some of the writing:

That film’s substantial changes are on full display here. The Fantastic Beasts castle is virtually identical; if they did create any drawings for that one, I haven’t seen them.


The real danger in studying these closely is that they refer to all the countless detail drawings that have not surfaced, and likely never will. Always leaves me feeling like the proverbial mouse for whom that cookie was simply not enough.

But ultimately, there’s a real beauty in all these drawings, even if I always find myself wanting more. I’m grateful to the deeply skilled drafters who brought these to life, and to the folks who’ve made them available to us fans!

Starting the Back Cliffs & Ravine

We’ve now got four chunks of Hogwarts’s original terrain finished. In my model, they’re divided as follows:

The blue chunk below the viaduct entrance is separate from the purple chunk below the Long Gallery because the blue chunk was redone in Goblet of Fire. The gold and green chunks on the other side could have been combined with each other and/or the blue chunk, but separating them improves sculpting performance.

The next chunk I added was a small patch that’s exclusive to Prisoner of Azkaban. They slightly built up the area just beneath the corner of the Great Hall, giving it a slightly different profile. (All of this terrain had to be redone when the Great Hall was shifted in Goblet of Fire, but the redesign was more similar to the POA version than to the original.)

Sorcerer’s Stone on the left, Prisoner of Azkaban on the right:

Another view:

But there were bigger changes in POA, of course. When they added the clock tower, wooden bridge, and so on, the surrounding terrain was totally redone. So in creating the bluffs that originally led down to the lake back there, I have to be able to swap them out with the POA version without affecting the adjacent terrain (shown in green above).

Techniques here are the same as what we’ve already seen, although it’s interesting to see the updated rock textures (sans moss) on the base mesh…

This is where photogrammetry stops being useful and I just have to closely study the few available reference images. (Blueprints aren’t super helpful either, since the terrain only follows them very, very roughly.) Another complication is that some VFX shots actually cut off parts of the miniature, particularly in this area; in those cases, I’m trying to treat the complete miniature itself as canon.

More base mesh:

No, you’re not crazy – the mesh protrudes right through the walls of the terrace in some spots. That’ll be fixed soon enough; it’s not hard to shave off excess landscape.

What’s going to be harder is the ravine between the two halves of the castle. That’s where even photo reference starts to dry up, at least for this original version of the castle. Photogrammetry from the big overhead shot in Chamber of Secrets will help me with the north side of the ravine, so I decided to work on that before trying to tackle the south side:

Meanwhile, around the front side, I’ve finally added the tiny lower walkway that seems to curve through the base of the stone bridge:

Sadly, I still can’t find any clear, reliable, pre-POA information on where exactly that walkway goes on the other side of the bridge. I’m starting to think that the one available SS-era floor plan of this area isn’t accurate.

This post is getting long…I’ll save further progress for the next one!

Continuing the Curtain Walls

Relatively short post today. We’ll start off with some orthographic views of the POA model, by request. This is the state of the model before the progress you’ll see later in this post.

I always enjoy these blueprint-style perspective-less views.

Anyway, onward to today’s update. Let’s start fleshing out the remaining walls surrounding the training grounds! I’m kinda doing the COS version, since most of this is covered by a new hillside from POA onward, but that’s okay.

I hadn’t touched this area since late March 2019…crazy to think that it’s now been over 2 years since I started this whole project!

There’s not a lot of reference for this area of the miniature, but I have found some shots. Between those and photos of the real thing at Alnwick Castle, I think my results are pretty accurate. Interestingly, that guerite (small lookout tower) closest to the camera seems to have been slightly redesigned partway through the construction of the model. I’ve gone with the final design that was glimpsed – if only barely – in the films.

The next structure along the walls is Alnwick Castle’s barbican and gatehouse. (This is the building from which Neville falls and breaks his wrist in the first film.) I had already done a bit of work on this structure as part of an early attempt at recreating Alnwick itself – here’s an old render from this post:

I built this to the same scale as the main Hogwarts model, so it was easy enough to drop that into place and add brick textures:

As we’ve seen with other areas, I’ve built the walls so they go quite a ways down. From this view inside the training grounds, the lowest parts will eventually be covered up by grassy lawns. But on the outside, the terrain is rocky and uneven, and in some areas it slopes downward to reveal the lower areas of the wall. It’s easiest to just make the walls really deep and then cover a lot of it up with the terrain later on.

Fortunately, there are some nice orthographic drawings of the barbican/gatehouse structure on a placard at the location. These provide some very helpful reference. As always, my goal is to capture at least one of these, in roughly descending order of importance:

  1. The onscreen appearance and imagined reality of the castle in the films (which is achieved through a mixture of location shoots, miniatures, CGI, etc.)
  2. The main 1:24 scale VFX miniature of the whole castle
  3. The corresponding real-life filming location

These do not always agree, and there are significant gaps in the reference for the first two, so finding the right compromises can be tricky. For instance, this shot in Sorcerer’s Stone shows Neville’s POV as he nearly impales himself on a statue:

I’m not sure about the background, but the foreground architecture is all CG, and it matches neither the real-life location nor the miniature…although the corresponding spots at the location and on the miniature are never shown onscreen. To make matters worse, in the live-action location shots that follow, the statue (which I believe was installed just for the film) has moved to a different corner of the structure. So there is no single coherent reality for me to replicate.

In this particular case, my approach will be to ignore this quick shot altogether and aim instead for the real location with the added statues and other set dressings. But I’ll save that for the next post.

Starting the Training Grounds Tower

Holy crap! I can’t believe we’ve arrived at the final major tower of Hogwarts! I’ve been eager and afraid to tackle it because of its complex geometry and the limited reference available. Let’s jump in!

The training grounds tower was added to the original castle out of sheer necessity. Alnwick Castle was used as a major filming location so they needed it to be present in the miniature. Stuart Craig’s team tweaked its footprint a bit and built it up into a much taller complex of towers; the bottom floors just looked like Alnwick while the upper floors took their stylistic cues from the original castle’s other conical turrets. Evidently Mr. Craig didn’t like the vertical extensions, because they were totally redone for the second film in a style that slightly foreshadowed the more Gothic look that would take over in the third film. (Interestingly, some COS shots still feature the SS version.) That revision stuck around till Half-Blood Prince, when it was replaced with a single tower echoing the bell towers’ design.

Since I’m working on the Azkaban castle right now, it’s that second iteration of the tower that I’m focusing on. And “focus” is indeed the right word, because I’ve spent a lot of time just staring at reference images and…thinking. Trying to piece it all together. Eventually, I started working on the facade toward the right:

This is the project’s first render with the OptiX denoiser, which wasn’t compatible with my GPU till Blender 2.90. Denoising is critical with path tracers like the Cycles render engine, where speeding up the render introduces more noise. I was using Open Image Denoise before, but OptiX is faster and it’s retaining more detail, so I’m pretty stoked!

Anyway, training grounds tower. It’s proving as challenging as I feared/hoped it would be. The modeling itself is not particularly difficult, but the paucity of high-quality reference images makes it difficult to piece together all the details, especially since I want to get the scale right.

I’m keeping an eye on the original version too, since the lower section is identical and I want to make sure I can reuse it without any issues.

In a twist that will shock precisely zero longtime readers, I’m finding lots of small discrepancies between shots of miniatures, location shoots at Alnwick Castle, CG long shots, etc. As usual, I’m striving for something of a happy medium, but weighted toward the main 1/24th-scale miniature.

There’s still a lot more to do on this structure, but it’s been 10 days since I last shared my progress and I think I’ll save further progress for my next post.

A Detour on the Grand Staircase

All right…the main model is still going strong, but I’ve found myself intrigued by a side project: the grand staircase, AKA marble staircase. Much like a parking garage, its interwoven spiraling structures are hard for my brain to visualize, which makes them fascinating to reconstruct.

I’ve specifically focused on the version seen in the first two films…after that, it went through some changes, though those changes remained subtle until Deathly Hallows. But in the first two films, it seems to have been brought to life with the same miniature and full-sized partial set – with digital augmentation. (Incidentally, based off of the few images of the miniature I’ve found, I’m pretty sure it was built on its side at somewhere around 1:3 scale…but don’t quote me on that. If I’m right, that would make the miniature over 50 feet long.) [EDIT: I’ve now found a source that claims it was a 40-foot miniature built at 1:8 scale, which doesn’t seem to work mathematically. I’m not sure what to make of this.]

Initially, my primary goal was to replicate the set. I figured the miniature was kind of its own thing, and I got to work aligning technical drawings and photogrammetry and so forth just for the set. (Each of those small orange shapes is where the camera was for a specific frame from the film…pretty cool to see how the camera moved through the space!)

After more closely studying both films, I came to realize that the available reference material does consistently and explicitly establish the spatial relationships between the set and the miniature. (Thank goodness the different paintings and frames provide excellent reference points!) So I changed tack: the new goal was to create a single model that brought the set, the miniature, and the digital elements together. This was aided by a bit of photogrammetry from Chamber of Secrets that worked WAY better than I thought it would:

So the good news is that I had a lot of information to work with. The bad news is…it was a lot of information! This room is enormous and very repetitive, so it’s easy to get lost in the reference images and forget which staircase is which. I tried to just jump right in with the modeling, but confusion set in pretty fast, so I decided this would just be an exploratory first pass. I kept this mockup simple and not super precise. Still, I kept getting lost, so I spent a long while color coding flights of stairs in both the model and in my reference images. Here’s a glimpse of just part of that process:

It looks like a gaudy mess, but for the first time in my life, I understood the complex geometry of the grand staircase! Things I learned:

  1. In plan view, the stairs form three adjacent squares. The flights that actually move are all part of the middle square.
  2. There were definitely at least 36 flights in the miniature – more likely 38, but I can’t find a clear angle confirming the last 2. Regardless, these cover 19 different levels, each 10 feet high. Almost every levels has 2 landings on opposite walls of the room. (I’m hesitant to call these floors, since Hogwarts isn’t really supposed to have 19 of those…but each landing does have a door…)
  3. In the miniature’s “default configuration”, so to speak, the flights are organized into two separate helical pathways. In the middle floors, these each spiral in a clockwise direction as they ascend on opposite sides of the room. Toward the top and bottom, the two pathways intertwine so they can switch sides. Through most of the model, the two paths are identical; they’re just rotated 180 degrees relative to each other.
  4. The bottom-most level is a bit irregular and doesn’t follow rule #3.
  5. If all the flights that form part of the middle square rotate 90 degrees from their bases, you end up with more of a DNA-like double helix, as opposed to two side-by-side helices.
  6. In the first film, we look all the way up and the stairs seem to continue into infinity. The most distant stairs were added digitally to obscure the top of the miniature. These aren’t part of my model.
  7. In the second film, the camera moves swiftly downward through the miniature; the set is composited in toward the bottom. Below the set are still more stairs; these were created by shooting the miniature again from a different angle and compositing it in as the bottom.

Clear as mud, right? Yeah, it’s hard to visualize. But the rough mockup was a success in that it gave me a clear roadmap for making a serious attempt at modeling the grand staircase. I’ve already begun, and I’m looking forward to sharing the details in a future post! In the meantime, here’s an orthogonal elevation-style view of the mockup, just for fun.