# How do I draw to scale

How do I draw objects to scale. When I draw a cube and check using the NKEY the size x,y,z are all equal to 1. When I draw a UV SPhere and check using NKEY the size x,y,z are all equal to 1, yet the two objects appear to be different sizes. My grid size is 1 and the cube is 2 wide and the sphere is about 3 wide. I was expecting that both objects in the x-direction would be the same?

the size values are relative. when creating a sphere, the radius is one grid unit, hence the diameter 2 GU’s. a cube has edges with the length of 2 GU’s. however, you can scale each object and hit CTRL+A. this will keep the new size (compared to other objects) but reset the numerical values for size to 1.

blender hasn’t methods for precise measurement and unit definition. if you want CAD, then it’s not well suited. it’s more for visualization and an artistic approach to 3D.

i don’t wanna start another such thread, there are plenty of them on this forum. use the search function to get a clue.

marin

Thank you, yes the cube has edges with length of 2 GU’s (1 GU from center to edge), however the sphere radius is not 1 GU it looks more like 1.4 GU (outside diameter is 2.8GU’s) even though the sizex=1, sizey=1 and sizez=1.

All circular objects created (UV SPhere, IcoSPhere, circle, cylinder, tube) appear to be about 1.4 GU’s in radius when created.

I would like to be able to create objects and know there relative size to each other fairly accurately.

Do I have a setting wrong?

solmax wrote :

the size values are relative. when creating a sphere, the radius is one grid unit, hence the diameter 2 GU’s.

The radius of a sphere is exactly the square root of 2 grid units, approx. 1.4142…

tg_blender wrote :

I would like to be able to create objects and know there relative size to each other fairly accurately.

The grid units don’t have to be 1 blender unit big : open the panel under 3D window header/View/View Properties and set there the Spacing to 0.70710678118655 ; don’t worry if the display doesn’t reflect that degree of precision since Blender will take it into account internally : with it you will be able to create a sphere of (close enough for most practical purposes) 1 blender unit in radius. Take advantage of the situation to create a cone, a circle, a cylinder…
I store such precisely measured primitives on layer 20 of my default display, the one I saved using ctrl+u.

Hope this helps

Jean

of course you’re right