Units of measurement...

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Units of measurement...

Post by browman » Fri Nov 01, 2002 10:43 am

This one has puzzled me for a while, I'd love to be able to figure out more accurate placement of objects in a scene, and be able to build models that are done to a proper scale (i.e. Metric units, switchable).

What I'd like to see is a permanently available numeric display (perhaps in a buttonwindow), of where the cursor is, the xyz extents of the current object at its current scaling, and when editing. It would also be nice to be able to find the length of an edge, when selected.

( :? Knowing me, this functionality is already there, and I just haven't found it yet! )

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Post by ton » Sat Nov 02, 2002 2:08 pm

Pressing 'N' will pop up a series of buttons with number info.
A wish-list feature of course is having this permanently somewhere, and expanded to other measurement tools like distance or edge lenght.

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Post by browman » Tue Nov 05, 2002 10:50 am

I knew all about that one, but it just shows you how much an object is scaled, not it's absolute size. As soon as you "Apply" the scaling, it will show 1x1x1 even if your mesh is 50x20x100.

IMHO this functionality is essential, especially when creating movies that consist of more than one scene, otherwise your scaling goes completely to pot...

I don't like counting grid squares, gives me a headache...

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Post by Knowmad » Tue Nov 26, 2002 2:08 am

I was also frustrated with this in the Blender 1.x days. There were problems with scaling (later I'd discover I was the prob.) one trick I taught my self was to biuld my own 'Ruler'. I'd put them in a locked layer, one for each view t,rs,ls. mostly theyd get lost,resized,or in the way.
now I just reajust the grid by a mutipul of my desired scaling factor.
and/or use a python script to biuld my meshes. at some point though we all get cozy to the bacic geometric theroms. dont wory thoug the head-aches go away (or at least the math/Geometry/square-counting ones :wink: ). then theres the whole question of what one is using for a camera lens ratio, camera angle, distance, fov. oh, theres that buzz agian,happens evey time before my head feals like it fell into a Blender!

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Post by animats » Mon Dec 02, 2002 8:40 pm

Blender should know what units it is working in. That's needed for import, export, and physics.

The zoom range seems a bit restrictive, too. If you're building a big world, Blender doesn't seem to support enough range of scale.

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Post by SirDude » Mon Dec 02, 2002 9:32 pm

The whole reason the units are not set to a specific scale is because
you need to use various scales depending on what you are working
on. (i.e. if your building a solar system you better not be using microns)
If your building a nanomachine you better not be using inches.

If you do your going to get massive errors computers just don't deal
with large numbers well. To do it right you need to pick the approprate scale for what your working on. If your worried about
it open up one of the text windows and write down what scale your
using. Then when people inport/export your stuff they can
resize it approprately.

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Post by vaniasmrkovski » Sun Jul 04, 2004 9:31 pm

Came across this old post in a search I did trying to find a solution to my problem, so I'm resurrecting the topic....

I've been taking advantage of the Python scripting Library module and have created a LoadLibrary script which loads specified files from other areas. My plans are to make this whole bit connected to a database and to have an engine which will load or unload various bits that are out of scope.

My project is the creation of a village, so I have objects that are scaled down to the millimeter, and up to a hundredth of a mile. But the village itself spans a much larger range, and I have encountered a few problems, even trying to take into account the ability to scale objects which contain meshes.

To help me along in my quest, I have a .blend file called "_unitsofmeasure.blend" which contains millimetercubed, centimetercubed, inchcubed, footcubed, yardcubed, metercubed, hundredthkmcubed and hundredthmilecubed objects. Experimenting, I found I had to stop here because of a few limitations with Blender 2.33a.

a) Using international standards, I used statistics to figure out exactly how a mile, my largest unit, relates to a millimeter, my smallest. I found I had to settle on 1 pixel = 1 cm, because if I got much smaller, the significant digits of the larger numbers would be off. That is, if I wanted 1 cm = 1 pixel, my attempt to get 1 mile = 160934.4 would fail because I found my mesh had a ceiling of -1000 to 1000, but if I tried to use 1 pixel = 100 cm, I would find my millimeter would become equal to 0.0005, which would always round up to 0.001.

b) Having decided to just create a "HundredthMileCube" reference object, I was able to keep the millimeter. I decided to try to make the mesh stay within the bounds of -1000 to 1000, but to scale the OBJECTS up or down as needed. Then I found I was unable to even SEE my objects because of the clipping.

c) I tried creating a camera object, and this helped a little bit. Now I was able to see more than just the user-centric browser (as opposed to Front, Side, Top), but I was still unable to see the whole thing.

d) I also found the camera had a problem when I tried to go too high. I moved my camera some 2000 or 3000 pixels up with the grabber, and it popped back to a point closer to the origin.

BINGO! I figured out one of the problems. If I have my Number Panel visible, it immediately locks me back to 1000 for the axis that has gone over. But if I close the number panel, I don't have this problem.

Conclusion: I disagree that it is really all that much of a help to have Blender stay measure agnostic. I have a great need to keep a universal constant because I am working with objects that range greatly in size. But even if I use my units of measure blender file for reference, I am further complicated by the fact that I cannot see everything I am working with, and the number panel is placing arbitrary limits on my work.

I'll work with scripting to help me, create functions which scale down or up as needed, but that's not optimal.

By the way, what does the Physics engine use as a reference? Gravity of 9.8 in real physics means 9.8 meters per second per second. That would be visibly different if it were 9.8 km per second, and since Blender does not have dimensions, there is a problem.


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