How much is a Blender unit?

[FreakyDude]

1 BU is what you want it to be. A lot of people seem to use 1 BU=1m.

selecting in blender:
rmb=select
alt+rmb=loop select
ctrl+alt+rmb=ring select
shift=add/remove from selection
L=add element to selection
shift L=remove element from selection
inverse selection=ctrl+I

lmb=place 3D cursor
drag lmb=gesture (line for grab, circle for rotate, V for scale)
drag lmb+ctrl= lasso select
shift +drag lmb+ctrl= add/remove from selection

tab=object mode/edit mode toggle.
ctrl+tab=(edit mode)toggle vertex/edge/face mode, enable multi by selecting and pressing shift in the header buttons)
(object mode) toggle object mode/weight paint mode
shift+tab= toggle magnetic snap on/off (off= grid snap with ctrl, on is vertex/face/median blahblah snap)

A=select/deselect all
B once= box select
B twice= paint select
G/R/S=grab/rotate/scale hotkeys. Use in combination with X/Y/Z, XX/YY/ZZ, shift+X/Y/Z, shift+XX/YY/ZZ for axis constraints. Use ctrl to snap to grid(or degrees)/magnetic snap

select+r+45+X+X makes you rotate your selection 90degrees along the local X axis.

the pivots and orientation:
alt+space=choose orientation
ctrl+space=choose manipulator (again, combine by pressing shift and multiple on the header.
.>=3Dcursor
ctrl+,<=median

some edit basics:
k=knife, knife+ctrl snaps to vertex
w=special menu
ctrl+e=edge special menu
x=delete (or remove an edgeloop while keeping faces bridged)
alt+m=merge menu.

that should get you a long way.
Happy blending.

[Eugenio]

Thanks a lot for all those shortcuts! Although I knew most of them, there are some very useful new ones...

About Blender units, as I said, how to deal with photorealistic renderers (indigo, Yaf(a)Ray, luxrenderer, etc.), light decays, dynamics and all these stuff? Or can I set how much a BU is?

Regards,

Jr.

[jrs100000]

The BU is arbitrary so any physical measure assigned to it would be assigned by the exporter or the render engine, not by Blender. 1 BU =1 meter is a fairly common conversion and is probably a good place to start. If you need a more definite answer you should ask on the message board of whatever render engine you are using or write an email to the maintainer of your export script.

[Shenan]

I know that softimage units are also "whatever you want them to be", however I learned that at least in XSI, when you start using simulations (hard body, soft body, maybe particles?) you need to assume that that 1 SI unit = 10cm for the simulations to be realistic.

Wouldn't the same kind of situation apply in Blender? Or does blender magically figure out how large your objects are supposed to be?

[jrs100000]

Physics simulations in Blender are preset to operate under approximately Earth-like conditions with a scale of BU = 1 meter. These settings can be changed to reflect different scales if desired.

Edit : Everyone seems to really want a non-arbitrary number assigned to the BU, but there is a reason that wont happen. Models built with very large or very small numbers of BUs cause rounding errors and result in all sorts of slowdowns and/or glitches. If 1 BU was set to equal 1 meter and somebody tried to make a scale model of the solar system or a scale model of a single molecule Blender would not function properly. 1 BU = 1 meter is a good rule of thumb for most objects but not all exporters or importers follow this rule and not all models can be built this way.

[Eugenio]

Thanks for the answers guys! I imaginated that it works like that. And I really don't want Blender to change it. In 3dsmax we can set scene scale and it can become a HUGE mess pretty much. You really can screw things up with it...

I like the idea of working as each BU = 1cm or 10cm...a meter is way too much, IMHO. A standard character size would be below 2 units! Well, that's just me...

Regards,

Jr.

[FreakyDude]

Got that right, all my characters would be 20 meters tall then. I rescaled all of them the other day, and they seemed just to damn tiny. Or it would be very akward to work at such a small scale.

[sundialsvc4]

There is no absolute scale to "Blender units." However, there definitely is a relative scale ... that is to say, "a sense of proportion."

When I am doing models, I usually think in terms of "1 unit = 1 foot," or something. It really does not matter what I choose, provided that I choose the same thing throughout the project.

The output of physical simulations can be scaled to suit whatever "mental model" you have come up with. And sometimes, you do find yourself tweaking those knobs just to come up with "what looks good." The bottom line, after all, is to come up with a visual result that is both believable and effective... whatever t'heck that means in any given situation.

[freen]

I like the idea of working as each BU = 1cm or 10cm...a meter is way too much, IMHO. A standard character size would be below 2 units! Well, that's just me...


I agree, the BU=1m common scale doesn't work for characters, and you end up doing a lot of stuff with really small decimals, which is annoying when the selectors only display 3 places.

Just as well it's arbitrary!
;)

[ysvry]

I agree, the BU=2 puppies in the window :P, whats better then freedom one bu is whater u want it to be.

[Michael-Williamson]

I dunno...

I thought computers were supposed to be very good at repetitive tasks and maths 'n stuff....

WHy not have somewhere in a blend set a BU = 1m or whatever?

Many programs allow you to type offsets in dialogs as a "real" scale. It's easier! you don't have to do the maths in your head...


I personally like being able to mix imperial and metric in dialogues too: type 10mm or 6'3" or whatever, have the program do the conversion for me!

Give me the choice to display imperial or metric values at any time, let me set the display precision ( km, m, mm, nm...)

Ok , problems could arise with the simulators.... but they all assume 1bu = 1m so THAT shouldn't be a problem to feed them realworld scales converted to the BU scale

What happens if you append or link objects with different BU definitions? well, this is where all the programs that allow this get confusing and problems arise...

you're importing into a scene, so use the scenes definition....

or I guess you add a dialog to "use master" or "import scale"or whatever, but that is always in need of a paragraph for each option to be clear exactly which way 'round it is....

As for precision issues, you're still arbitrarily defining the size of a BU, just putting a nicer interface on it, and you gain a lot in simulations by always having a real world referance point.

[jrs100000]

WHy not have somewhere in a blend set a BU = 1m or whatever?


This sounds to me like exactly the sort of thing plugins are for. There is already the caliper script that sort of does what you are looking for. Caliper Script (http://wiki.blender.org/index.php/Scripts/Manual/CAD/Caliper)

Id guess that if people are interested it could be expanded to get all of the functionality you are after.

[Bliz]

Good question [OP]. My main app. is currently Maya and you are specifically told in the docs that 1 maya unit is treated internally within the code as 1cm.
If the blender code assumes one unit to be a metre for physics purposes then I'm going for that.
Characters at that scale should be fine (?) I can't imagine I'd need to move something less than a millimetre (the precision 3 decimel points gives you) but I haven't yet worked on a character in blender so I might find out I'm wrong further down the line.

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