How accurate

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conchyliferous
Posts: 2
Joined: Fri Feb 05, 2010 9:45 am

How accurate

Postby conchyliferous » Fri Feb 05, 2010 10:02 am

I'm about to create a research simulator based on Ogre. Now I need a tool to create models. Just ordinary models including textured blocks and cylinders.

My questions are:
1. Is Blender accurate enough for serious (publishable) research. If I specify something to be 1.43 m, I need it to be exactly that. I know there are no units in Blender, but I wonder if everything is perfectly proportional. If the answer is 'NO', could you please give me some advice on other tools?

2. If I use Blender for my modeling, which format should I use when using in Ogre.

Thanks.

pep
Posts: 32
Joined: Wed Dec 16, 2009 7:58 pm
Location: Costa Rica

Postby pep » Fri Feb 05, 2010 1:53 pm

blender has units, and i understand that they are perfectly proportional. You should have a look at Robert Burke's tutorial "Precision Modeling" at

http://homepage.ntlworld.com/r.burke2/p ... ling1.html

In fact it's a 151 Pages/613 images book with some very interesting arguments about... well, precision modeling.

I would like to avail myself the opportunity to start collecting our specific wishlist for Blender in Academic and research environment.

Would conventional (inch and centimeters) units option be the first one?

stiv
Posts: 3646
Joined: Tue Aug 05, 2003 7:58 am
Location: 45N 86W

Postby stiv » Fri Feb 05, 2010 4:41 pm

If I specify something to be 1.43 m, I need it to be exactly that.


Exactly that? You wouldn't be happy with 1.42999999999999993783 ?

Computers do math with binary numbers. These are not the same as real numbers from math class. Nasty surprises await the naive on their first expose to digital math and numeric analysis.

Blender uses standard C floats for math which give you about 7 significant digits and a range of about +- 10**38.

I don't know what 'perfectly proportional' means in this instance.

conchyliferous
Posts: 2
Joined: Fri Feb 05, 2010 9:45 am

Postby conchyliferous » Fri Feb 05, 2010 6:28 pm

blender has units, and i understand that they are perfectly proportional.


Blender uses standard C floats for math which give you about 7 significant digits and a range of about +- 10**38.


Thanks, that is what I needed to know.

http://homepage.ntlworld.com/r.burke2/precision_modelling1.html


Superb! Thanks.

Computers do math with binary numbers. These are not the same as real numbers from math class.


Of course I know that. But that is not the point of this question.

MonZop
Posts: 25
Joined: Wed Dec 16, 2009 9:51 am
Location: Pisa

Postby MonZop » Mon Feb 08, 2010 12:47 pm

pep wrote:
Would conventional (inch and centimeters) units option be the first one?


Thanks for the offer. However academics and scientists don't actually use the inches, feet and other body parts (not for measuring, i mean).
As for the decimal metric system, in Blender there are 8 orders of magnitude.
In some scenes we use objects (atoms) measured in Angstrom (10 e-10 meters) with motions of fractions of Angstroms. In other scenes we have objects as big as 100 micrometers (10 e-4) or even larger. We typically have 1 BU = 10 e-9 (for proteins) or e-6 (for cells)

People modelling, say , earthquakes would need a completely different scale system, but the fact that it is decimal makes it very easy to use Blender as is (establish 1 BU = 1 km, for example)

So, I would say, you're welcome to make a converter, but it should be flexible to be useful to everyone!

thanks!
monica


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