Always Use A Scale Reference When Modeling In 3D
By Neil Blevins
Created On: Aug 27th 2023

How the 3d object you're modeling interacts with the whole environment is frequently more important than the object itself, and so getting scale right at the beginning will save everyone a ton of headache. This short video discusses the advantages of always considering the scale of the 3D object you're creating, especially when working with a team, and discuses some tricks to make sure you get the correct scale from the beginning. Consider it an important reminder, always start with the correct scale.

You have two choices with this lesson, watch me discuss the issue in the video below, or read the full text.

So this may seem like a small thing, but it's a very important thing, and can be easily forgotten as you're focused on modeling an object in 3d and not yet worrying about how that object will fit into the larger environment. But how your objects interacts with the whole is frequently more important than the object itself, and so getting scale right at the beginning will save everyone a ton of headache.

What sorts of headaches? Well, beyond having to rescale the object when it reaches the environment, there's plenty of other ways this can go sideways. Some material types rely on world space for their coordinate system, and so scaling your object will mess up your material. If you're doing simulations such as water or fire, and someone accidently uses an object that's the wrong size, "scaling" the effect is usually not as easy as grabbing it and using a Scale tool. And if you rig a character that's the wrong size, scaling the rig can cause all sorts of errors, and broken geometry.

So it's far easier to make sure the scale of your object is right in the first place.

As a somewhat silly but still pertient example, there's this great film called "This Is Spinal Tap" from the 80s, and there's a scene in the film that pertains to this, so spolier alert, I'm going to tell you one of the jokes. The movie is about a ficticious rock band, and in one scene they want to play a song about "Stone Henge", and they want a stage prop of one of the pillars, so they draw a diagram. And they accidently mark it as 18 inches tall instead of 18 feet. So when they play the concert, instead of this mammoth rock that instills awe and wonder in the crowd, they get a ridiculous 2 foot rock. The lesson here is don't be like spinal tap, make sure you have the scale right at the beginning.

Now it's not totally the artists fault. When you load up almost any piece of 3d software there's nothing in your scene to tell you the scale of anything. I mean, there's a grid. But what size is the grid? What size is a grid square? And is it the small grid square or this larger grid square that's 1 unit? And to find out the size of a unit, you have to go find it hidden several menus deep. So 3d software in general could be a lot better at making scale obvious.

So what I do to solve this is have a 6 foot tall human model in my scene. Now I'm biased since I am a 6 foot tall human, but it's not the specific size, the important part is I always have the human in the scene so I can always turn it on and see the scale of what I'm modeling. I also have some other scaled models, like a car, or a single floor of an apartment building. And I use a script I wrote years ago in 3dsmax to quickly pull these assets into my scene, so I can always check.

At Pixar, we tended to have a flat plane that had a picture of our Production Designer on it, so when he came to your desk and asked to see the scale of the object, you'd just load in the flat plane so he could immediately tell sizes. Again, the important part isn't what you use as scale reference, the important part is using it.

If you don't have a quick way to load a scale object, another technique is to always start with one. For example, in 3dsmax, if you make a file called maxstart.max and place it in the default scenes directory, when you reset a scene or start 3dsmax from scratch, it will not load a blank file, but instead it will load your maxstart file, and anything in it. So make a blank scene, place your human in there, save it as maxstart, and now everytime you start max you'll have your scale reference ready. And there are other similar systems for the other major 3d programs out there.

So please consider using a scale reference when modeling in 3d, it will save you tons of trouble later on, and will make life easier for the next person in the pipeline if you're working at a studio.

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