Metric (or measuring) system failed.

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hanpari
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Joined: Wed Nov 07, 2012 10:07 am

Metric (or measuring) system failed.

Post by hanpari » Sat Sep 28, 2013 8:29 pm

I use metric system and made 1 cubic meter and saved it as a file.

Then, I used metric system and scaled it to 0,01 and save the same cube as 1 cubic centimeter into new file.

So far so good.

Then I created new file and appended my cubic meter and my cubic centimeter and guess what...?

Yes, both objects had the same dimensions! From one point of view it is OK because both cubes are 1 Blender unit.


From second point of view it is very very bad. If, for example, is Blender used to 3d print of assembly of such two "different" objects the result will be disaster and cause Blender to seem untrustworthy.

CoDEmanX
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Post by CoDEmanX » Sun Sep 29, 2013 2:42 am

you might need to apply transformation > scale before saving your first cube
I'm sitting, waiting, wishing, building Blender in superstition...

brasshat
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Post by brasshat » Sun Sep 29, 2013 9:55 am

In English, the word "scale" has multiple meaning. Blender uses at least two of them. One use is to refer to the size of an object. In his usage, an item about the size of a human being might be referred to as in "human scale", while an object the size of a mountain might likewise be considered "geological scale". But among the other uses of the word "scale" is to refer to a units of dimensions, especially when relating measurements between two similar items. For example, one map might be in one scale (for example, one inch depicts 2,000 meters, while another map is in a different scale.

In English, Blender uses the word scale to refer to two different meanings. In transformation in object and edit mode, "scale" refers to the size of an objec; changing the size of the object is accomplished by scaling it up or down. But the word scale is used in the "units" panel of the screen tab of the properties window, in the sense of a measuring tool. So changing the size there on the same object in two different windows, does not change the size of the object, it changes the distance between units on the measuring tool (in this case, a virtual one). To make your 1 cm cube have the proportional size to the 1 meter cube, you need to use the "scale" transform methods.

ns

hanpari
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Joined: Wed Nov 07, 2012 10:07 am

Post by hanpari » Sun Sep 29, 2013 11:09 am

Thank you both for answering.

Actually, with all respect I know the basics. Yes, I applied the scale transform (Ctrl-A) to get exactly 1 Blender unit cube. When I was talking about scale I was talking about setting as follows:

Scene - > Units to Metric > Scale (under metric menu)

For 1 meter example I used Scale 1
For 1 centimeter example I used Scale 0,01

(The mentioned Scale is located in SCENE menu, not in 3d Viewport Properties.

Than you can press N and see the metric units in Dimensions I am talking about.

I hope I made myself clearer.

Allow me add one important thing. I am really aware I have the same units measured by Blender units and I am aware it is right know feature of Blender.

But surely, using metric system in such manner is IMHO very confusing with regards to new users.

My target was rather to point it out then to ask why it is like that. Sorry to confuse both of you (supposing you were thinking I am asking for help ) :oops:

CoDEmanX
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Location: Germany

Post by CoDEmanX » Sun Sep 29, 2013 6:07 pm

well, if you append/link an object from another .blend, it won't look at the scene settings (=metrics). It's arguable if it should respect the metric settings of another .blend.

I suggest you never change the scene scale, but scale down your 1 cm cube to 0.01 units (1 unit = 1 m = 100 cm)
I'm sitting, waiting, wishing, building Blender in superstition...

hanpari
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Joined: Wed Nov 07, 2012 10:07 am

Post by hanpari » Sun Sep 29, 2013 6:56 pm

1/ I am not asking for help. But thank you.
2/ I wanted to report curious behaviour of Blender from point of starting or inexperience CAD user. :idea:
3/ Measurements are essential considering fact Blender is aiming for 3d print.

Howgh :)

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