unit measurements, precise architectural modeling

The interface, modeling, 3d editing tools, import/export, feature requests, etc

Moderators: jesterKing, stiv

gk
Posts: 0
Joined: Sat Sep 03, 2005 5:38 am

units

Post by gk »

Re: joeri

"Even Maya and Max are no longer cad tools. No industrial design company uses Maya todo their cad."
Maya, 3ds Max and Lighwave are all commercial "modelling" tools that are used a lot more than blender. What I and I think everyone before me who requested this feature would like would be able to use units of any sort to help us model the real world without having to guess or use the grid or a virtual ruler. This is not a quest to get 'm' appended to every unit, and I don't think anyone is using blender to design a car.

I think what you are suggesting is that I model every object to be of the same size and then use the transform dialog to scale them to desired size.

It is a workaround but still not very convinient, if this is not what you are suggesting could you please try and explain again.

wavk
Posts: 126
Joined: Wed Oct 16, 2002 9:58 am
Location: The Netherlands
Contact:

Post by wavk »

Aha! I think we're getting to the point now.

Hm... now you bring it up, the size in the 'n' panel might be named a bit wierd. The size really means scale. It has nothing to do with the dimensions, but with scaling.

You need to understand that Blender works with two coordinate systems, the global and the local. Objects are placed, rotated and scaled in global space. The size parameter doesn't tell you anything about the size, but about the scaling of the mesh it contains.

The models themselves are in local space. If the object's size is 0.5, all coordinates in th mesh are halved.

You should never scale objects in global space when doing cad or architecture, that will be very frustrating. It's more or less meant for animation, or placing objects with different sizes, in artsy ways.

wavk
Posts: 126
Joined: Wed Oct 16, 2002 9:58 am
Location: The Netherlands
Contact:

Post by wavk »

Anyway, THE way to measure a distance between two points is enter editmode, go to the edit buttons and turn on 'draw edge lenght'. Select the two point, duplicate with SHIFT+D and make it an edge with 'f'. Voila, the way to make a measurement. Hope that helps,

Wybren

nemyax
Posts: 0
Joined: Mon May 31, 2004 12:34 pm

Post by nemyax »

joeri wrote:Blender is an artist tool.
Artist == someone who constantly eyeballs stuff? Funny reasoning.
joeri wrote:Even Maya and Max are no longer cad tools.
Never were.
joeri wrote:all I can think of is the distance tool in Maya
The distanceBetween node is more use in many situations.

Now that Blender displays edge lengths, the ruler approach is obsolete. You can simply create a mesh of two vertices, snap them to the points you need and check the length of the edge between the verts. Just be careful not to scale this mesh in object mode.
Ideasman proposed something like this in an earlier post.

joeri
Posts: 96
Joined: Fri Jan 10, 2003 6:41 pm
Contact:

Post by joeri »

"and I don't think anyone is using blender to design a car. "

What are you talking about here? design or engineer?

Design is done with: Sketchbook, Painter, StudioTools, Rhyno.
Engineer is done with: ProE, SolidWorks.
Animation is done with: Maya, Lightwave, 3d Max, Blender.
3d Game modeling: 3d Max, Wings, Blender.
Modeling: Rhyno, Modo, Wings, Blender.
2d Cad drawings:

So, no need for CAD tools in blender. Just as there are little to few CAD tools in Maya or Lightwave.

"would like would be able to use units of any sort to help us model the real world "
BU works just fine as a unit.
And how come your 20 turns into a 1 is probably because you put your vertex on 20 and expect your object boundbox to become size 20; but that's not what the size matrix is about.

Hmm, I see wavk beat me to it.
i'll quote from another threat
The size you are reading in the property window is not global size.
As you can see the cube is not size 1,1,1 in global space, it's size 2,2,2 in global space. It goes from grid -1,-1,-1 to grid 1,1,1.

The local size of the object is 1,1,1. Pretty useless to you as you are approaching size of objects as a measure tool, when blender is giving you information on how it's going to map textures on the object.

If you scale the object by half. (you can do this by typing in .5 is the sizeX Y & Z in the properties window) and then apply the size to the object: ctrl-A, enter then the object once again is size 1,1,1. But also 1,1,1 in global space.
How can this be? Well, if you look at the positions of the verteces inside the cube object (TAB) then things might get more clear.
In the given cube the lower left vertex is on -1,-1,-1 local space and the top right is on 1,1,1. Multiplied by the objects size (1,1,1) gives a global position of -1,-1,-1 to 1,1,1. Now if you scale the object down to 1/2 it's size the verteces will stay inside the object on -1,-1,-1 -- 1,1,1. But 1 * 0.5 is 0.5 in global space. When you apply the size from the object to the vertece (ctrl-a) then visualy nothing changes but data is stored differently:
lower left vertex will be on -.5,-.5,-5 and top right on .5,.5,.5 . And the object will get size 1,1,1

See? the size is a multiplier of the local locations of the verteces.
Not a measurement of the object in global space.

So how does this help you? not at all.
But how can you be helped?

Image

Can you tell me what the sizeX,Y & Z should read in an object like this?

joeri
Posts: 96
Joined: Fri Jan 10, 2003 6:41 pm
Contact:

Post by joeri »

nemyax wrote:
joeri wrote:Blender is an artist tool.
Artist == someone who constantly eyeballs stuff? Funny reasoning.
== ???
nemyax wrote:
joeri wrote:Even Maya and Max are no longer cad tools.
Never were.
http://www.alias.com/eng/about/history/ ... shtml#1986

dumbf
Posts: 0
Joined: Wed Aug 31, 2005 2:16 pm

Post by dumbf »

Maybe, you CAD guys if you could just import your CAD stuff cleanly into Blender, there would be no need to keep banging your head over CAD features in blender. blenders never going to have CAD features like your typical CAD applications have and then if blender did have CAD features I bet they would'nt work like the CAD your used to. so best use your fave CAD software and import cleanly into blender.

you need good import of a most widely used CAD format.

gk
Posts: 0
Joined: Sat Sep 03, 2005 5:38 am

Post by gk »

Firstly, I am not doing CAD, and I don't think this is a CAD issue. I am modelling the real world and trying to model objects on their real conterparts with sizes etc. And I know I'll have to point out again that I don't mean metres, any makey up unit will do including blender units, I am ok with imagining the 'm' on the end.

Re: wavk
"You should never scale objects in global space when doing cad or architecture, that will be very frustrating. It's more or less meant for animation, or placing objects with different sizes, in artsy ways."
Yes, this is exactly my problem. Ideally I'd like to be able to resize all objects with global dimensions rather than scaling them. Imagine the transformations panel except with sizeX meaning exactly that.

Perhaps it should be renamed to scaleX in the existing transformations panel?

Thanks


Re: joeri

I am sure I can be helped and I think I've described my problem and what I would like reasonably clearly, but maybe not by you as you're being a bit of a pedantic ass.

re your last question x & y should be about 4 & 3 respectively, of course it could be different depending on the angle that I can't see from here.

wavk
Posts: 126
Joined: Wed Oct 16, 2002 9:58 am
Location: The Netherlands
Contact:

Post by wavk »

I don't see the problem in adding CAD tools. If they fit in right into the interface and workflow, what is there to loose? It's just not on the top of the priority list. Blender is primarily aimed at making beuatiful pictures and animations a fast speeds.

I'm doing architectural visualisations with Blender, using CAD data from another application. So that CAD data is a good workaround for the lack of CAD features in Blender. Which brings me to another point, what exactly do people think CAD tools are? Measurments? Units? Snapping would be a relief. I think sooner or later we'll have snapping in Blender. That would be so cool. Being able to rotate and move stuff around in leterally a snap. When I think of CAD tools in the architectural field, the biggest thing that pops to my mind is snapping, all kinds of snapping. Measurements are primarily added for printing.

Also numeric entry could be improved, it's not very user friendly and not supported in all tools. Also I understand the difficulty of say creating a sphere with a diameter of say 5 units. When adding a sphere, you get a shpere with a diameter of 2.828 units. It would help to have it be one unit. Then you could just scale it according. All examples of Blender not being perfect, but I have good hopes things will be improved. Look at the speed Blender is moving right now. Look at the big transformation recode. Very boring work with little visible results, but they did it and paved the way for transformation widgets and lots of cool things in the future.

I agree with dumbf that the work on the import scripts would be very welcome. DXF is really poorly supported. I need to literally tear CAD drawings to pieces to get them imported in Blender. The recent improvement of the VRML '97 export script was very welcome, now exporting to 3d studio got much better!

I guess it's frustrating to fix up a scene that started off with wrong dimensions... I've had my share of it when a dxf drawing imported at the wrong scale (not fault of Blender). It really saves a lot of time getting things right from the start. Enter right dimensions right away and there's really not much need of measuring.

So I think of course you can ask for and discuss features related to CAD, but don't demand them like they should have been there... Blender coders don't code for money, they choose to code what they want to do. So get them excited to code the tools, make detailed proposals why it would be so cool.

Have fun,

Wybren

LetterRip
Posts: 0
Joined: Thu Mar 25, 2004 7:03 am

Post by LetterRip »

On IRC Ton stated a desire to discuss CAD features at the next Blen Con, so those of you who are adamnant that Blender will never have CAD features might well be wrong.

The reason that XSI, Maya, et al don't have specifically CAD oriented features is due to their parent companies segmenting their markets. Blender is not constrained by wanting a target to only serve a particular niche market. The overlap between CAD and 3D apps is so substantial that it would be rather odd if Blender didn't expand its capabilities to encompass the needs of CAD users as well.

LetterRip

wavk
Posts: 126
Joined: Wed Oct 16, 2002 9:58 am
Location: The Netherlands
Contact:

Post by wavk »

Perfect! I see it's sooner instead of later. I'll be there to join the discussion :D

joeri
Posts: 96
Joined: Fri Jan 10, 2003 6:41 pm
Contact:

Post by joeri »

gk wrote:I am sure I can be helped and I think I've described my problem and what I would like reasonably clearly, but maybe not by you as you're being a bit of a pedantic ass.
I don't know what pedantic means but the ass part is out of line.
I can state my opinion just as much as you can without being called names.
gk wrote:re your last question x & y should be about 4 & 3 respectively, of course it could be different depending on the angle that I can't see from here.
Not true, the angle is perfect visable, it's 0,0,0...

But I guess what you want is a tool that will set the (local) boundingbox to global sizes depending on the local rotation. That should not be hard to implement.

This is already possible in blender:
Image

But then you need to make sure your internal verteces are in order:
Image

I think all your need is for a tool that will do this for you.

joeri
Posts: 96
Joined: Fri Jan 10, 2003 6:41 pm
Contact:

Post by joeri »

wavk wrote:I don't see the problem in adding CAD tools. If they fit in right into the interface and workflow, what is there to loose? It's just not on the top of the priority list. Blender is primarily aimed at making beuatiful pictures and animations a fast speeds.
There is no idealogical problem with adding CAD tools, it's not a 'religion' thing. And it's also not that I don't want CAD tools in blender. I would be more than happy if there where trimmable nurbs surfaces, boolean functions on volumes, history alterations, and resolution independant models.

But the Interface&Tools section of the blender forum is about feasable proposations. New features that fit into current architecture. And I challenge anyone with a 'brilliant' "new" idea to come up with a solution how to implement that in the current blender.
It's just to simple to drop feature bombs on this forum, they will not be implemented (trust me I've been around a while) unless they where going to be implemented anyway.
Or unless they show dedication to be solved by the requester himself.

stiv
Posts: 0
Joined: Tue Aug 05, 2003 7:58 am
Location: 45N 86W

Post by stiv »

I don't see the problem in adding CAD tools. If they fit in right into the interface and workflow, what is there to lose?
One thing you guys are missing is that the problem is not the UI. The problem is the underlying data structures. CAD programs use structures like implicit surfaces, half-planes and trimmed nurb patches because those data structures support the kinds of operations a CAD program features. Both CAD and 3D animation deal with objects in space, (space-time in the case of animation!) but they have different fundamental concepts of what those objects are and what they can do. A model of a piston connected to a crank may need constraints, but it does not need morph targets or vertex keys.

The reason Blender's boolean operations are problematic is not because the coders are lazy clueless slackers, but because the underlying mesh data structure makes the problem inherently complex. The long and passionate discussion here about object dimensions and how they are determined is simply another view of the fact that CAD and animation treat objects differently.

Without CAD-like data structures, adding CAD-like features to blender will always be difficult and hacky.

stiv
Posts: 0
Joined: Tue Aug 05, 2003 7:58 am
Location: 45N 86W

Post by stiv »

I don't see the problem in adding CAD tools. If they fit in right into the interface and workflow, what is there to lose?
One thing you guys are missing is that the problem is not the UI. The problem is the underlying data structures. CAD programs use structures like implicit surfaces, half-planes and trimmed nurb patches because those data structures support the kinds of operations a CAD program features. Both CAD and 3D animation deal with objects in space, (space-time in the case of animation!) but they have different fundamental concepts of what those objects are and what they can do. A model of a piston connected to a crank may need constraints, but it does not need morph targets or vertex keys.

The reason Blender's boolean operations are problematic is not because the coders are lazy clueless slackers, but because the underlying mesh data structure makes the problem inherently complex. The long and passionate discussion here about object dimensions and how they are determined is simply another view of the fact that CAD and animation treat objects differently.

Without CAD-like data structures, adding CAD-like features to blender will always be difficult and hacky.

Post Reply