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First time in metric system and I can't figure out what is the dimension in blender, first of all the scale of a cube is one and the dimension is 2:
enter image description here
scaling the edge of only one edge up in edit mode turns up the dimension of the whole object to the size of the scale of the edge, and not the object in an average:
enter image description here

enter image description here

So, I'm a bit confused, about what the dimension in blender actually refer to, and what the difference between it and scale is?

EDIT: What if the bounding box length and the edge are of equal size:
enter image description here

BumbleBee
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  • Somewhat related: http://blender.stackexchange.com/questions/47318/why-do-the-measurements-of-this-object-seem-erroneous/47320#47320 and http://blender.stackexchange.com/questions/7298/why-is-it-important-to-apply-transformation-to-an-objects-data –  Jan 21 '17 at 06:49

1 Answers1

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Scale is a factor applied to an object non-destructively, on top of its true real world dimensions. It doesn't really modify in underlying geometry or mesh data unless applied.

A 2 units cube with a scale of 2 will result in a total size of 4 units; a scale factor of 0.5 will result in a final size 1 unit. Scaling doesn't change the actual objects size, so if you enter Edit Mode on a cube with a scale factor of 2 its edges will still show dimensions with a perceived factor of 0.5 in relation to Object Mode because that is their true size.

Also see related Why do the measurements of this object seem erroneous?

Since scale is applied per object, several objects can share the same objectdata (shape defining geometry) but appear to have different sizes because each instance has a different scale factor, despite its geometry being the same and thus having the same true dimensions in Edit Mode.

Object dimensions are the result of the scale factor multiplied by the actual geometry size, and are measured relative to the size of its bounding box. If you change one edge size in Edit Mode it will change the cube's bounding box size, and hence its dimensions.

Duarte Farrajota Ramos
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  • if we were to make a 2" edge then, we can't rely on the dimension panel then, better take it from the edge length? – BumbleBee Jan 21 '17 at 06:47
  • You can always rely on the dimensions panel, it will always display the size of the bounding box. Now if that is the actual dimension you want to know or not is a another matter. – Duarte Farrajota Ramos Jan 21 '17 at 06:50
  • Why are the edge length and dimension showing unequal sizes when the bounding box length is equal to the edge length? (Please see my edit) – BumbleBee Jan 21 '17 at 06:59
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    The dimensions panel is absolute measurements, the scale is relative –  Jan 21 '17 at 06:59
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    @BumbleBee if your scale is not applied the measurements in edit mode are not correct, they are relative to the scale of the object. –  Jan 21 '17 at 07:01
  • @cegaton, omitting the scale part, is the edge length also the absolute measurement of the length of an edge?(Please see my edit above) – BumbleBee Jan 21 '17 at 07:03
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    only if the scale has been applied. –  Jan 21 '17 at 07:06
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    Please read the links: http://blender.stackexchange.com/questions/47318/why-do-the-measurements-of-this-object-seem-erroneous/47320#47320 AND http://blender.stackexchange.com/questions/7298/why-is-it-important-to-apply-transformation-to-an-objects-data –  Jan 21 '17 at 07:08
  • @cegaton, Though I found it while doing, but, to confirm, does the dimension correspond to the local axes? And, also , changing the dimension would also change the scale, and to have accurate measurements, do we apply the scale from time to time? – BumbleBee Jan 21 '17 at 07:09
  • Let us continue this discussion in chat. –  Jan 21 '17 at 07:11