Author Topic: Drawing Axonometric using the Scale - Skew - Rotate (SSR) method.  (Read 12035 times)

March 04, 2015, 10:33:12 AM
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ragstian

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Hi.

Based on a thread in Inkscapeforum.com I made a guide;



Feedback welcome!
« Last Edit: March 04, 2015, 12:57:01 PM by ragstian »
Good Luck!
RGDS
Ragnar

March 04, 2015, 12:12:12 PM
Reply #1

Lazur

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Hi.

Nice guide!


Some notes:
Never heard the term "axiometric", I belive it should be called isometric this case.
Axonometric illustrations and axonometry in general refers to a drawing made with a Cartesian grid with x, y, z, axises in any direction and scale. 
Isometric drawings are such axonometric images, where the axises are in 120? to eachother, and the scales of the axises are 1:1:1.


If the transformation panel is used, 86,60254% for scaling may be quite precise, but not to the max.
(0.48 uses only 3 digits)
Nor that appealing to users not liking math.
Some sort of snapping may do the trick?

For that practical reason, I would also draw a square covering the views, moving them to the bottom, and grouping the objects together
-so in the end there would be 3 object with a square bounding box.

How to scale a square to that (3^0,5)*50% height?
An equilateral triangle would do the trick of the same edge.
Could be snapped it's bounding box to the square's bounding box edge, to make it the same size.

If snapping does not work -converting it to guides and pulling the diagonal guide lines to the square's right corners can be a solution.
Pulling guides from the rulers and changing them direction may also work but it then won't reduce the typing.
Then the horizontal guide (a new one pulled from top ruler in the second case) line needs to be snapped to the diagonal guide lines intersection.

After that, the square can be scaled to the equilateral triangle's bounding box/horizontal guide line, producing the exact scale.


Then, the skewing and rotating can be done much easier by holding Ctrl and moving the handles of the bounding box.


But, if the transformation panel is used, adding a - mark may make it too complicated on a larger project.
Why not to use only one value for each kind of transformation?
-30? skew is equal to mirroring the object (H), applying a 30?skew, and mirroring it back (H).
For the rotate, the cheapo solution would be to click the rotate -90? rotation icon when in object select mode, then apply 30? rotation twice.
(Hmm that may double the inaccuracy, even if not notable.)


In general it is right, but simply using such transformations without a bit of background, can hardly solve cases like drawing a chimney over the gable.
Or drawing cast shadows after.

March 04, 2015, 12:50:55 PM
Reply #2

brynn

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Very nice, Ragnar!  You're welcome to upload to Illustrations for Text Tutorials album.  And if you don't have time, I could make an "article"/ tutorial that can be listed here - http://forum.inkscapecommunity.com/index.php?action=articles;cat=2  (or probably http://forum.inkscapecommunity.com/index.php?action=articles;cat=5)  (although if I do it, I'll be shown as the author  :hmm:)

(Instructions in the Text Tutorials section of this message - http://forum.inkscapecommunity.com/index.php?topic=51.0.  It really doesn't take very long, once you have the tutorial written, that's the hard part.)

(axiometric seems like a blending of axonomic and isometric --  I have no idea if it's a real word or not -- it seems real  :D)
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March 04, 2015, 01:24:40 PM
Reply #3

ragstian

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Hi.

Quote from: Lazur
Never heard the term "axiometric", I belive it should be called isometric this case.
Updated the guide and thread heading. Thanks for pointing this out.
Quote from: Lazur
If the transformation panel is used, 86,60254% for scaling may be quite precise, but not to the max.
Ok, will update the guide with a more precise number. Here it is with more precision;86.6025403784.

I'am not sure if I understand your "For that practical reason, I would also draw a square covering the views, moving them to the bottom, and grouping the objects together - so in the end there would be 3 object with a square bounding box. " Do you mean to have one box around the resulting cubes - above the "barns"?

I just tried to make this simple - a more thorough and accurate guide might be nice but might discourage the "casual" Inkscape user.
Will have your suggestions in mind for a "proper" tutorial.

brynn;A proper tutorial might be better than this "one-pager" - I tried to cram all the info into one page, will have a look at some of the other (yours) tutorials for a better version number two. Stay tuned. Can upload to your "Tutorials Gallery" if you feel that's a better solution than using dropbox.

RGDS
Ragnar

« Last Edit: March 04, 2015, 06:10:43 PM by ragstian »
Good Luck!
RGDS
Ragnar

March 04, 2015, 02:26:06 PM
Reply #4

Lazur

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Someting similar as in the attachment.

My concern about scaling by % is the 3 digits limit (still on 0.48, opensuse doesn't have an update on inkscape yet.)
If the square is 500 px high as in the example, 433,0127019 px would be a close value, but
scaled by 86,603%, 433,015 px will be the result.
Which, after the skewing and rotating, results in a 500,003 px height for a cube, instead of 500 px.


For the casual users it is a nightmare I guess, because they would need to learn to use some of the tools to achieve a result based on a concept they probably don't know either.

Like transforming the sides that way? Why? How would that lead to a right image? Impossible ---oh wait, what kind of magic this is?!

March 04, 2015, 02:57:59 PM
Reply #5

brynn

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brynn;A proper tutorial might be better than this "one-pager" - I tried to cram all the info into one page, will have a look at some of the other (yours) tutorials for a better version number two. Stay tuned. Can upload to your "Tutorials Gallery" if you feel that's a better solution than using dropbox.

I think all our tutorials are 1 page, although a couple of Lazur's are very long pages.  Actually, for this forum's software, we use Articles for tutorials, and  you can't make a 2 page article.  But you can put 2 large images (or up to...I forget how many...6 or 10, I could look it up). 

It should be fine hosted in dropbox.  But I understand (maybe wrongly) that there's a limit to free uploads at dropbox.  So you have 90 mb of space here (which is not final - I may increase it at some point) in your personal gallery.  But the Illustrations for Text Tutorials album is unlimited space.  (I think some of Lazur's tutorials' images are hosted at Open Clipart.)
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March 04, 2015, 03:21:26 PM
Reply #6

Lazur

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Yes, for tutorial svg sources I like to make them available as public domain.
Also it can get some extra attention, with the articles linked there.
Just need to figure out how to embed links better in the descriptions and/or to the svg-s.

For example the brush tutorial's svg at ocal got clicked on 240 times, while the circular meander pattern here has 28 views.
From those who probably saw it previously in the article.

March 04, 2015, 03:45:52 PM
Reply #7

brynn

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Does OC have Tutorial section or category or something?  Just curious.

Edit
Maybe should?
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March 04, 2015, 03:59:12 PM
Reply #8

Lazur

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Does OC have Tutorial section or category or something?  Just curious.

Edit
Maybe should?



 :ot1:

To organise works, you can add any tags, like "inkscape community", and a search for the tag could show them all. 

Also, you can create collecions.
A bit unpolished that you need to click twice the add to collection button, but it works.

For example:

[ad]
technical drawing maaterial

geometric art

challenges

spam remix
[/ad]


Well an important note is (to myself as well...), that the first image of the collection will be the thumbnail image of the collection, so it's wise to make the first image accordingly.

 :ot1:

March 05, 2015, 01:45:23 PM
Reply #9

ragstian

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Hi.

Tested the Isometric - ( Axiometric? ) drawing style
- by drawing my bandsaw
- all from memory
- it might look very different in real life!
- the "brandname" is my "invention" the brand is different but the color is the same.

« Last Edit: April 01, 2015, 03:30:39 AM by ragstian »
Good Luck!
RGDS
Ragnar

March 05, 2015, 04:33:25 PM
Reply #10

brynn

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Nice!  You have a wood shop?  I think it would be a fun hobby  :D
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March 05, 2015, 07:12:46 PM
Reply #11

ragstian

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Hi.

Quote from: Lazur
(still on 0.48, opensuse doesn't have an update on inkscape yet.)
For installation instructions for SuSE 13.2 see here
No need to wait! Got mine installed OK using OpenSuSE as a "virtual machine" with Oracle Virtualbox on Win8.1 - works like  charm!

I got one question about your "hobby-horse" which you seem to ride quite often - inkscape accuracy. Does the (lack of) precision have any significance apart from the pure theoretical aspect? In my admittedly amateurish work I never see the effect of any inaccuracy, should I pay more attention to this or is "good enough" good enough? (Read that sentence again - my English teacher would have been proud! - Maybe not! :D)

Quote from: brynn
Nice!  You have a wood shop?  I think it would be a fun hobby
It is! Set it up a while back - then we moved, have been away for eight years now - hopefully I will get to spend some "quality time" in the shop (mancave?) when we return home this summer.

Good Luck!
RGDS
Ragnar

March 07, 2015, 02:17:32 AM
Reply #12

Lazur

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For installation instructions for SuSE 13.2 see here
No need to wait! Got mine installed OK using OpenSuSE as a "virtual machine" with Oracle Virtualbox on Win8.1 - works like  charm!

That's some good news, thank's for the heads up!

Quote (selected)
I got one question about your "hobby-horse" which you seem to ride quite often - inkscape accuracy. Does the (lack of) precision have any significance apart from the pure theoretical aspect? In my admittedly amateurish work I never see the effect of any inaccuracy, should I pay more attention to this or is "good enough" good enough? (Read that sentence again - my English teacher would have been proud! - Maybe not! :D

It causes me fustration if I type in a value and after a while it changes from ,000 to something else.
Other than that, if there are 2 nodes next to eachother in a 0,00x distance, I can hardly see which one to go by, which one to use as a snapping target.
In general, the inaccuracy of the nodes cause much less trouble than the inaccuracy of the curves.
Like ruler-compass based constructions use alot of circle intersecting, each producing a larger mismatch. And, with each line those add up and the result won't look right.

Rather theoretical, but an example could be this one, constructing a "real" trace of an implement.

Or drawing an Apollonian gasket and
tracery.
« Last Edit: March 07, 2015, 10:34:10 AM by Lazur »