Mold tool question

[ZEBtoonz]

I have an image (see below) which I need to add some perspective to. The original was from a PDF so I could easily import it as a vector into Xtreme. As you can see, even though the picture angles off in "mock" perspective, it is not true perspective in which the back upright is smaller and the lines gradually converge towards a vanishing point. I believe this is a convention of architectural drawings so that the draftsman can simulate perspective without going to all the extra work of a horizon line and vanishing points.

So, I've been trying to adjust the picture using the Mold tool, but to no avail. I can get the back upright smaller and the lines angling off to the left to converge towards a vanishing point, but then, I cannot get the lines angling off to the right, to converge. Perhaps I am trying to do something which isn't possible. If so, I will just have to use this pic as a base and then set up a perspective grid and, piece by piece, adjust my drawing accordingly. But if there is a shortcut, bring it on!

[ss-kalm]

......I believe this is a convention of architectural drawings so that the draftsman can simulate perspective ......

It's called "Isometric Projection" and the architects use it and perspective. The one that really looks wrong is the "Axonometric Projection". Isometric is 30°/30° and Axonometric is 45°/0°

[ZEBtoonz]

Thanks, Keith! I vaguely remember the term isometric from my high school drafting class. Had a 30/60 plastic triangle for drawing the lines, etc.

So, can I fix it with the mold tool?

[ss-kalm]

Probably not as you adjust the mold to get the perspective right on the left, the right side will twist the wrong way. However if you use two pictures (cropped to suit) and faded together you may be able to fake perspective on both, but it will take some work.

Why can't I copy and paste your picture. All I get is a blank square ....?

[ss-kalm]

Well, I can't make it work ...... applying the mould tool make it disappear !!!

[MarkMyWords]

This is one of the big problems with the mold tool that really limits it's usefulness. If we could detach the mold then position it and then re-attach it, but it will only affect the image, distort it, when adjusted after "re-attachment".

Hmm... that doesn't seem very clear. what I mean is that now, when you detach a mold and position it, then re-attach it, the image is distorted from the basic start position as if the mold was not detached.

[Burpee]

Keith, I get the same problem when I try to use the mould tool with anything except simple vector shapes.

[steve.ledger]

Zeb I might be misunderstanding, but using the 'default' perspective mould-tool selection and adjusting the corners appropriately, I seem to be able to achieve what (I think) you were referring to??

[JET]

It's called "Isometric Projection" and the architects use it and perspective. The one that really looks wrong is the "Axonometric Projection". Isometric is 30°/30° and Axonometric is 45°/0°

It's kind of a "pet subject" with me, so I hope no one takes offense at the following correction:

Isometric drawing is axonometric drawing.

Isometric: Think "same measure for all three axes."

Dimetric: Think "two measures." (One of them is used on two axes.)

Trimetric: Think "three measures." (A different measure for each axis.)

Axonometric: Think "measured along axes." (Thus, isometric, dimetric, trimetric are all axonometric.)

The awkward-looking "45°" projection you mention is oblique projection.

The purpose of axonometric drawing's using parallel perspective (or "othographic projection") is not to avoid the "difficulty" of drawing a horizon line, vanishing points, and converging perspective rays. It is done for far more important reasons: technical clarity and accuracy.

Clarity: Think of an exploded parts illustration of a motorcycle engine. When you need to buy a part and/or see its assembly order, clarity and accuracy is just as important at the rear of the assembly as it is in the fore.

Accuracy: A properly-drawn axonometric drawing is just as accurate--and just as measurable--as the typical three-view "blueprint" with its top, side, front views. But the axonometric is obviously much more intuitive to discern the actual shape of an object. So think of axonometric drawing as a 'bridge' between the working drawings of the engineering room and the customer's eyes.

Nor is even isometric (as opposed to dimetric or trimetric) necessarily "easier" to construct than converging perspective. Yes, isometric drawing is simple for box-shaped things (like the table example) with nothing but perpendicular surfaces aligned to the drawing axes. But consider: What if the box is not oriented parallel to the drawing axes? For example, suppose the boxy table has a cereal box sitting on top of it, but the box is turned, say, 28° relative to the table edges (simple rotation). How do you correctly construct that? What if that box is not only rotated, but is also tilted (compound rotation)?

Now consider that most objects we illustrate (thankfully) are not so boringly boxy in shape. Have you ever seen an isometric illustration of a crankshaft? Or a bicycle frame?

Fact is, nothing in axonometric drawing is arbitrary. The drawing is either correct--or it's wrong. There is no middle ground. And axonometric method can correctly construct all of the subjects described above, in isometric, dimetric, and trimetric, including objects of any shape, and with objects in simple or compound rotation relative to the drawing axes.

So no, it's not at all about a 'lazy man's alternative' to the kind of converging perspective that our eyes see. It's about conveying the same technical clarity and accuracy at all "depths" of the drawing. That's very important in things like motorycle engine service manuals, lawn sprinkler systems, bicycle assembly instructions, Lego kit instructions--and just about every kind of product illustration in between.

(Traditional on-the-board technical illustrators, by the way, have also long employed construction methods for converging perspective that are more mechanically-accurate than the kind of arbitrary "horizon with two vanishing points" typically taught in art classes.)

Again, not meaning to sound like "Mr. Knowitall". But correct axonometric drawing is a bit of an under-appreciated 'art' these days, and I thought others here might appreciate knowing.

JET

[JET]

Zeb I might be misunderstanding, but using the 'default' perspective mould-tool selection and adjusting the corners appropriately, I seem to be able to achieve what (I think) you were referring to??

Sledger,

Using the mould tool's perspective distortion on the already-drawn-in-perspective (albeit parallel perspective) table does not a proper converging perspective drawing make.

Note that in your mould tool distortion the horizontal members of the top of the structure now flay apart at the rear, whereas they should actually converge toward a right-side vanishing point.

JET