3D Modeling Standards: Real-World Scale

by Michele Bousquet

With regard to scale, a digital 3D model is a funny thing. If the file says the building is 3 meters tall, the model renders the same as if it were 300 meters tall (unless the scene uses scale-sensitive lighting, but most scenes don’t). Scale becomes important only when you merge the 3D model into a scene, a very common practice with TurboSquid customers. If a bunch of merged models are at different scales, the customer has to do extra work to make all the models work together, which involves guesswork (fast, but inaccurate) or time-consuming research to figure out exactly how big that thing is supposed to be.

The number of 3D models at TurboSquid that aren’t at real-world scale is surprising, especially when you consider how easy it is to model to scale in the first place, or to change the scale when you’re done modeling. Most 3D models can be re-scaled quickly and accurately with a few mouse clicks. Models with rigging or dynamics aren’t as easy to scale, but the vast majority of 3D models at TurboSquid consist of geometry only, which responds accurately to scaling.

If your models are already at real-world scale, be sure to mention this in the product description. Customers strongly prefer real-world scaled 3D models over the who-knows-what-scaling-was-used types of models. And if your models aren’t to real-world scale, you can improve your sales by making them so. Check out the videos below to find out how to check and change a 3D model’s scale in 3ds Max or Maya.

Both programs have a default scale. Maya uses centimeters (1 unit = 1 cm) while 3ds Max uses “generic” units that default to inches or centimeters depending on your geographic region (1 unit = 1 in or 1 cm). 3ds Max users that want maximum compatibility for exported file formats are best off using centimeters or meters for scale. In 3ds Max, you can always model in your preferred scale and change it later; if you model in inches, for example, then when you’re done you can change the units to centimeters using the tool shown in the video, and all measurements will convert automatically. Both 3ds Max and Maya also have tools for messing with the way the program handles unit scales under the hood, but it’s a bad idea to change these settings unless you have a definite reason for doing so. If you stick to the tools shown in the videos, you’ll be safe.

Are your models at real-world scale? Do you feel this gives you a competitive advantage at TurboSquid?

10 Responses to “3D Modeling Standards: Real-World Scale”

  1. Kupfer says:

    Always use a centimeter in his scenes, some of my colleagues use millimeters, when importing models from different scenes to be increased to 10 times

  2. Anonymous says:

    Digital-tutors: Modeling Interiors in 3ds Max…

    I think your post is similar and trackback it. Thanks…

  3. Jamie says:

    I’ve often thought of creating an object out of text that says: “This text is X inches long” and placing it in the scene before publishing. Or perhaps a cube that’s 12in with the dimension carved into it.

    Is that a silly idea or a good one?

  4. Magoo3D says:

    Isn´t easyest to scale using the SergoScript “Scale by 3 points”?

  5. Michele Bousquet says:

    > Is that a silly idea or a good one?
    Who says a silly idea can’t be a good one?

  6. DreiDe says:

    What is “real-world-scale”? If I model a house I choose meters not millimeters! If I model little things like a fly for example, I´ll choose mm not meters! So the model makes the “real-world-scale”. It´s a way of logic, I think.

  7. Cain says:

    What about scaling down? Its strange how the grid in 3ds max video is just like mine, but my model doesnt cover the whole grid and I need to scale my human down from 200 meters to 2 meters and when I do that my viewport messes up because the object is so small in the world space,even after resetting the scale. I cant zoom in up close to a vertice because the viewport slices my model open! It like there is a piece of glass in front of the viewport and it pushes into the model.

    Default size I have been working on:
    http://img26.imageshack.us/i/200m.jpg/

    Vertex selection on that default size (200m)
    http://img542.imageshack.us/i/vertexlarge.jpg/

    2 meter size or real human size:
    http://img444.imageshack.us/i/14020910.jpg/

    Vertex selection on that 2 meter resized model:
    http://img585.imageshack.us/i/vertsmall.jpg/

    Zoom tool:
    http://img696.imageshack.us/i/sameo.jpg/

    Field of view tool:
    http://img26.imageshack.us/i/fov0.jpg/

    Anyone know whats wrong?

  8. raymarcher says:

    Here is my cheat cheat for units in 3ds max:

    units

    general:
    -always set up the system unit before you import or create geometry
    -do not change system units in an existing scene
    -system units: 1 inch, leave as standard for compatability reasons
    -1 unit is 1 cm
    -display units: cm, important for fbx

    system units:
    -determines the actual scale of geometry
    -1 unit is size for smallest geometric detail of scene

    system unit calculator:
    -use the slider to enter the distance from the origin to see the resulting acuracy at that point

    display units:
    -affects how geometry is displayed in viewports
    -use whatever display unit, has no impact on scene

    file load units mismatch:
    -appears when opened file has different system unit settings than the current session
    -option 1: rescales to match current sytem unit settings
    -option 2: adopt, changes current system unit settings to settings opened file

  9. gorillamilk says:

    Great idea for Turbo Squid to put this in an email.

    Another good idea would be to have a check box when uploading the models.

    Example:

    Is your model to scale? Yes or No… and have it a required field before uploading.

    Either answer will allow you to upload, but at least the buyer would know ahead of time and be able to make a more informed decision.

  10. Hermes David Montes de oca Segovia says:

    Funny thing about those videos is that they are teaching how to scale to real world units and its recommended to do research and in the one with the plane, its scaling a boeing 737-400 to the size of a boeing 747-400 (at least twice as large plane), now thats a wrong scale! hahahaha

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