6 Basic Tips In Making 3D Models for AR (Augmented Reality)

Although AR has been around for a very long time — we still don’t have that “Ultimate Guide to Everything AR” yet — because as of now — the technology is evolving and AR applications are only recently booming. It still wows everyone with how cool and futuristic it looks and that more people gain access to smart yet cheap devices that are capable of playing AR everyday.

So anyway — since you stumbled upon my blog, I would assume you are either: a 3D artist, a developer, maybe both (ooor someone who just accidentally clicked my blog while scrolling) - and you’re now going to venture into the world of AR (insert rainbows and magical sfx) - but have little to no experience in creating apps that integrate it.

I’m no master or expert, but I do have experience in creating 3D content for AR and I-may-have-a-tip-or-two-for-you~

(It’s quite a long post — so I added TLDRs at the end of each point — for the lazy ones — like me.)

TIP 1: DECIDE ON A STYLE

Before anything else — you need to think about how your 3D assets should look in the real world. Would you like them to look as photorealistic as possible? — or do you want them to stand out and seem out of this world, cartoony, or intriguing?

Knowing what style you want matters — because this affects how you’re going to approach creating the 3D assets from here on: How smooth the models should be, how detailed their textures are, and how much you need to tweak to make it look seamless with the scene or eye catching and alienated.

TLDR: Decide if photorealistic or stylised/not photorealistic?

TIP 2: SIZE MATTERS

Since our goal is to place 3D Objects in the real world (regardless of the style), you have to ALWAYS model based on what their actual size is going to be in real life. So before doing anything else — set up your preferred unit of measurement in whatever 3D modelling software you use, and model based on its real life size.

Try your best to research for their standard sizes or whip out a measuring tape to get an idea on how big or small it would be. So that when you’re done and have to test in on a device — it will look just right.

TLDR: Create models in real life scale.

TIP 3: MESH COMPLEXITY

I’m gonna start to use them big 3D terminologies from here on out — starting with the word ‘Mesh’. So mesh is basically the overall shape of which was formed by a number of polygons — but I know you already know that. :)

And for those of you who have experience in creating models for games like me — then you may also be conscious about your Polycount. This is basically how many polygons there are currently in your model. The higher this number is — the more the device has to process, and we don’t want that of course.

So for objects that really do require a lot shapes and a lot of smooth edges which bumps up the polycount — we usually create different LODs for them — or Level Of Detail. Details are only noticed anyway when the object seen on the screen is near — so the trick is to create different versions of the same mesh but with lower polycount. So whenever the user comes near your 3D model — it will show the most detailed one — and when they go further away from it — they’ll be shown the ugliest- (I mean)- lower polycount version.

Also take note of how many 3D objects you will show in the scene — cause the sum of their polygons is what your device needs to process. Process that. :)

TLDR: Click and read this: LOD . Low polycount = less stress on device = good.

TIP 4: TEXTURE SIZE

AR applications are played in mobile devices — and as of 2019 — we still think about how to optimise file size so that the app isn’t heavy or that it takes too long to load and process stuff. So since we are gunning for mobile devices — always make sure to keep an eye on how high the resolutions of your texture images will be.

If you know a thing or two about PBR materials — then you are aware that they require multiple texture images — which means more file size. So best be careful about that too.

The usual sizes for a texture image in pixels are 512x512 ,1024x1024 , 2048x2048, and so on. Depending on how details should be sharp, and how important they are is how I determine how big or small the resolution would be.

TLDR: Textures are heavy in file size — be careful.

TIP 5: THE MODEL AND ITS ENVIRONMENT

In setting your model up with its possible environment — you have to consider the following: Reflections, Environment Light, and Shadows. Actually all three of them may already be handled by what ‘program’ you will use — as long as you set up your materials correctly. If you created a metal ball for example and had set the metallic and smoothness property to the highest value then it is expected to reflect the environment it will be put on.

The program should also be responsible for ‘Light Estimation’ — this is how the current environment will affect your 3d model. So let’s say you spawned it in a dark room (but with enough light so that the app detects the floor) — then your model should appear dark too.

Same goes for shadows as well. The program should automatically create shadows and occlusions for you.

But in cases that it won’t do all those three for you — you should just read my next point…

TLDR: Set up your materials so that it can properly react to any environment.

TIP 6: FAKING IT!

So in my experience before, but I’m not sure if it’s still applicable now, we (me and the awesome XR group I work with) needed to fake the shadows and the ambient occlusion of some of our AR models because for some reason the program didn’t generate it for us. :(

But actually, it might have helped though — since I can imagine generating all those in real time would eat up more processing power — which could potentially slow down the application. But again, I’m no expert, so do get a second opinion for this one. For shadows we created a simple ‘Plane’ and gave it a transparent shadow texture, and just placed it below the model so that it looked like it was placed on the floor and not floating.

Next is ambient occlusion, these are the dark creases that add depth to the sides of your models — it has a great impact in adding to the realism — so some programs do this for us — while others don’t. But never fear, you can actually just add in an ‘Occlusion Map’ or texture and Voilà! Darker edges — Yay!

Last, but most basically, fake smoothness, bumps, and details through textures. What I’m trying to say is — model and texture smartly. For example, you have small bolts in a small object. You don’t have to model the bolts themselves, you can just fake them by adding it to the texture and add bumps via a Normal Map.

It may take some time to determine what you can or cannot fake, we all level up with experience after all. So try and play with different ways to model. :)

TLDR: Sometimes, you have to put on your own shadows, bake occlusions, and rely on textures to fool people.

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And that’s basically it for my tips :) Thanks for dropping by! Hope this proves useful in your journey to exploring Augmented Reality~ ❤