# Are Illustrator 3D effects not calculating accurate values to construct with

I'm having an interesting issue I recently encountered when dealing with Illustrator 3D effects. I'm trying to explain this issue with a more simple example than it actually was.

I have two `isometric left` 3D cubes which I already have expanded to their appearance. Let's say these two cubes are two table legs of a desk. They are perfectly isometric left aligned to each other, but I don't know their distance.

Now I want to add the missing tabletop. I don't know how long the length of the tabletop should be so I thought I need to get the distance of those two anchor-points: So I checked transform, got `x, y` coordinates of both anchors and calculated the distance with an online calculator.

Let's assume the distance between these two points is `240pt`. I created a line to doublecheck this and it fitted perfectly from one anchor to the other.

So I created a 2D shape with the exact width of `240pt`, applied the same 3D effect as on the cubes, but it turned out: The tabletop was too short. I thought it must have to do with me mixing up some numbers, but I did it again and it did not work. I wanted to make sure that the way I do the calculation is correct, so I did the exact same thing in Cinema 4D, and it worked. Is Illustrator not actually calculating with proper values? Is it behaving differently when it comes to coordinates and 3D?

• Instead of calculating, why not just use the `Measure` tool to measure the distance between the points? Aug 19, 2016 at 14:45
• @Manly true, just wanted to test it with actual calculation Aug 20, 2016 at 21:32

No its accurate, in this sense, at least on my machine. But then depends on what you mean by accurate. I can easily show that cinema 4D is not accurate in lots of things.

Based on your description it seems you are in fact calculating the projected distance. Projected distance is not 1:1 proportional to non projected distance*. it is like flattening your 3D view and measuring distances from that (camera loses scale so you need to chose right sized scale to project it). Image 1: It works perfectly fine.

But, I rarely use this tool. If i want 3D geometry i will use a 3d application for that. If I need vector art I just export my geometry form 3d app into illustrator. Or then draw by hand to keep up my practice. Example of the former and a example of the later

PS: you can measure distances with the line tool

* Its possible to make a isometric cardinal axis be, but illustrator chooses to foreshorten instead of keep length, this is perfectly valid if not really practical. Nothing says post camera scaling is not possible.

• thanks for your answer. So according to your image you were able to make this work, the question is how? If I understand you correctly you mean that having a distance in 3D, creating a 2D object with this distance and then applying 3D effects does not work. Because 3D distances don't have the same "ratio" than 2D objects in Illustrator? Aug 19, 2016 at 7:17
• @supersize yes exactly mainly because ratio means nothing except in the isometric special case. Even Cinema4D does not preserve scale in orthographic cameras that are rendered out. I store all my original 2d paths so i can measure stuff in 2D. Aug 19, 2016 at 7:31
• could you refer to your image how you made this work? Did you basically applied the effect and transformed afterwards to make it fit properly? And why would you store the 2D paths to measure things for 3D if it wouldn't work properly anyway. I need to get a grasp on this, and I'm still missing some bits in my head. Aug 19, 2016 at 7:38
• @supersize the paths themselves always transform the same way. The ratio is fixed its each and every time the same. Its just not 1:1 to the 2S object so you can not just measure stuff from the projected thing. Aug 19, 2016 at 7:57
• For isometric views the ratio is about 0.8191 But different rotations have different ratios (to fit the view width) Aug 19, 2016 at 7:59

Select all areas 2d ago and the data groups and the command Extrude.