Notes: The Issue of Scale



Wikipedia defines "Scale Model" as a physical model, a representation or copy of an object that is larger or smaller than the actual size of the object, which seeks to maintain the relative proportions (the scale factor) of the physical size of the original object. Architects and engineers use scale as well when creating construction documents or "Blue-Prints" for use on site during costruction. Scale drawings have been described as drawings that show a real world object with accurate sizes except they have all been reduced or enlarged by a certain amount (refered to as the scale)."

The hardworking little train below is an example of a scale model of a real train.


When using 3D in Visual Effects or for Previsualization, theoretically everything you are going to build in your scene has a real world counterpart. The Filmback in the camera, the focal length of the camera, the height of the camera, etc. In this respect you are not working with clay, you are inputing real "data" in your scenes, and you need to be very careful in this regard. Everything should have a real scale. The degree you adhere to this should be based on each particular project's needs.





In Maya we have a few options for scale. You can access these by going to Window / Settings/Preferences / Preferences.

Typically when I build a set or a model that will be part of a larger set, I work in feet.

In Maya you have the choice of using Centimeter, Millimeters, Meters, Inches, Feet, or Yards.

The default working units for Maya are centimeters. These units work best with final gather settings, clipping plane settings, particles, etc.

My advice is to use the "centimeter" setting as a generic unit, and you can decide what scale it actually is. Typically for me one generic maya unit is equal to one foot. My working units settings match those on the left.


Some 3d programs just use generic units anyway, so this is not an issue (then you are already using generic units).


Each one of the grid spaces on the left is equal to one foot (in this case).
With my scale set, if I make a 1,1,1 cube I can call that a 1'-0" foot cube. It also corresponds to the grid in the scene.

A typical interior door size here in the U.S. is:

30" x 6'8" high x 1-3/8" thick

You will have to convert these numbers to a consistent decimal feet and inches (example: 6'-8" = 6.66').

If were were to build that door the converted dimensions would be:

2.5' wide x 6.666 high x .1375 thick.


This is a very simple object and should work very well to get the general point across.



The channel box info for our door looks like this on the left. They have all been converted to decimal feet w/ inches..nice and tidy.

We can use the measure tools in Maya to check these dimensions later.


Make sure "snap to point" is active.

Add a distance measure tool by going to:

Create / Measure Tools / Distance Tool (as shown on the left).

It may take a little getting used to, but you will need to make sure you snap the measure tool to the desired points...and now you can be sure confident about the dimensions of your model.


After you have verified your dimensions you can place these all under a locator or just delete them to maintain a neat and tidy scene.

The typical doorknob height it 36" (converts to 3'-0").


After you have verified your dimensions you can place these all under a locator or just delete them to maintain a neat and tidy scene.



Speed / MPH

Let's take a look at another situation. You are building a set and you need to calculate how fast your car (or Truck in this instance) is traveling. Our set is built to scale, so it's very easy to calculate how fast the car / truck is traveling in your scene.


I have built the roads to be 12.5 feet wide. You can measure your set with a Disto or other laser measuring device. Google Earth works fairly well for general dimensions. Don't do anything stupid like try to measure a busy street with a tape measure.


I have a model for a Toyota Tacoma Truck in this scene. Below are the dimensions for the truck I found online, and I have scaled the truck to match.

Wheelbase 127.4 (10.62)
Width (in.)72.2 (6)
Height (in.)65.7 (5.475)


Our scene is built to the scale of one unit = 1'-0" Let's say this shot calls for the truck to be traveling at 35 mph. This will require us to convert 35 mph to feet per second.


Multiply the speed in MPH by 5,280 feet per mile. The result is the speed in feet per hour. For example, 35 MPH is 184,800 feet per hour.

Divide the speed in feet per hour by 3,600 seconds per hour. The result is the speed in feet per second. For example, 184,800 feet per hour is 51.333 feet per second.












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