Axonometric?

[Rok]

Heeelp...I'm new to 3d Vectorworks,...so that's my excuse.Now that that's out the way.

;-)

I'm attempting to set up an axonometric from a true plan.The problem quite simply is,I can't...I don know how...I'm lost on how to do this.

So far,I think I understand that you should be able to achieve an axo in Oblique Cavalier 45.

But it doesn't work. The height (z)is correct but both (x and y) are too short.

Principles of an axo, object drawn at 45 degrees,all lengths are true(x,y,z).

Any ideas,would be cool.

Cheers

R

ps.Forgive me, if it's really simple(please refer to my first paragraph).

[JBC]

Rok, I think that the at heart of this matter is the distinction between an axonometric projection and an axonometric drawing. Within an axonometric projection all axes are foreshortened to a degree. In the case of an isometric setup all principle axes are foreshortened to an equal degree. When one does and this type of an axonometric drawing however, they will input the measurements true to scale, thus keeping a 1:1 ratio. Cavalier and Cabinet drawings can be drawn with equal scale, but have distortion with regards to the receding lines. As I understand your question the discrepancy in scale goes back to the computer projecting rather than drawing your model. I hope this helps, and doesn't confuse you as I am certainly no good at these types of drawings. That is one reason I like the computer so much. I've pulled the old Francis D.K. Ching book "Design Drawing" off the shelf and it makes things more clear for me. He does make an effort to emphasize the difference between an axonometric drawing and an axonometric projection. You should be able to scale your model to compensate the shortening of lines within an isometric view however. This would give the appearance of a drawn to scale view. Like I said before I am certainly no expert, but your question got me thinking. Perhaps one of the more seasoned forum persons will chime in to correct me, but I hope this at least give you some new leads.-Brendan

[islandmon]

The VW orthogonic projection is based on the octet angle tan30?=0.57735. Which equates to the tetra angle of 70.5288?. Which when div by 2 equates to the spheric angle of 35.2644?. Multiply the length of the lines by the scale factor=1/cos35.2644 = 1.224745, eg:

if you want the projection lengths to match the plan lengths of a 10x10x10 cube multiply the cubic XYZ by the scale factor.

[NickB]

This is an old topic I know, but one that was puzzling me, so in case anyone needs this in future...

To do what Rok was suggesting (a 'plan/elevation oblique' in Ching's terms):

1) select a straight 'Standard View' (i.e. 'top' if you want a true plan)

2) select an oblique 'Projection' (e.g. 'oblique cavalier 45')

Simple... a true plan and true lengths for the third dimension suitable for scaling from.

To choose which direction the oblique comes off at (i.e. which sides of the object are shown) use the 'Rotate 3D View...' command to rotate the plan relative to the direction of the oblique.

**Don't use any of the isometric views and/or orthographic projections, and don't try combining an isometric view with an oblique projection***

(all things that I tried several times over)

True the oblique lines don't run vertically from a plan turned 45o, but turn the piece of paper round and the effect is the same.

[ 12-02-2005, 08:00 PM: Message edited by: NickB ]