Isometric View Help


#1

For a while now i’ve been using the Parallel Projection > Iso View method to display my objects in isometric view, Though today I downloaded this plugin, http://sketchucation.com/forums/viewtopic.php?t=29018.

Which has made me quite anxious that the objects I have printed for my project are not true isometric views. So, I’m wondering what the difference is between the inital method I used and the plugin.

Thanks, also I’m sorry if this hasn’t made sense, I haven’t been using Sketchp for that long.


#2

I’m sorry if this hasn’t made sense, I haven’t been using Sketchp for that long.

Perhaps you can help me understand why you are even interested in an isometric view. The several forms of axonometric projection, including isometric, were developed as a means to produce a pictorial image of an object as a simplified alternative to true perspective, back when it was prohibitively difficult and time consuming to draw a true perspective in most cases, although they were clearly preferable. The trade-off was, isometric views appear distorted and unnatural, although they are relatively easy to draw by hand with a 30-60 triangle.

These days, when true perspective views are easy to create from a model, why would you wish to use an inferior isometric view?

All that having been said, “isometric” means “same scale” That is, each of the three receding axes are inclined an equal amount to the picture plane and consequently foreshortening affects each receding axis equally. This means there is only one correct orientation for an isometric: namely, each normal face is inclined to the picture plane by 35°16". Normal axes are 30° above or below horizontal (depending on whether you’re looking up or down at the object), and the vertical axis is vertical.

An isometric drawing is typically made at full scale. An isometric projection is made at about 82% of full scale to account for foreshortening.

But again, this stuff really only makes sense if you’re drawing this by hand with instruments. Dumbing down a 3D model to look like an isometric drawing makes no sense to me, unless perhaps you work in a museum or are planning a trip back to the 60s. It is exactly like throwing away information you’ve already paid for.

-Gully


Print Scale isnt true in isometric
#3

SketchUp has tons of problems with its parallel projection camera. This is a long-standing issue that needs to be fixed before large-scale uptake of the tool occurs across the board.


#4

Perspective views are great for visualization, but not for construction or measurement. They depend so much on the camera’s field of view angle, lens length, etc, that a model can be made to look properly proportioned when it’s not (and vice versa). Ortho or axo views are created around known angles. Parallel projection views in general serve the purpose of avoiding parallax errors when visually analyzing a model.


#5

Before fixing one needs to al least know what problems you are refering to. Could you sum (some of) them up please?


#6

You don’t “measure” a 3D model. You interrogate the model for exact dimensions using the original modeling software or a compatible viewer app. The view is immaterial.

The idea that you would scale a blueprint (forbidden in the world of engineering even in the days of paper drawings) rather than extract exact dimensions from the 3D database is somewhat astounding. Any construction or fabrication tolerance would immediately be gobbled up by measurement errors.

-Gully


#7

I’m glad I could impress you with ideas I’ve never even thought about!


#8

Awesome! Excited to see that Trimble folks are listening in.

I think that instead of saying SketchUp has lots of problems with its parallel projection subsystem, I should have said it has one long-standing graphical bug that causes loads of problems for users who find that sort of camera more conducive to their workflow.

Many users have found over the years that spending a little time orbiting around with the parallel projection camera causes geometry to disappear.

Google Search for “SketchUp parallel projection clipping”

The general solution is to switch to a perspective view. However, like the original poster, I need orthogonal views sometimes, and I actually prefer working in that mode where others prefer perspective mode.

I hope that answers your question. Thanks for making an awesome product.


#9

Clipping is not peculiar to SU, nor is it a “bug” in the sense of an unexpected error in the code. Clipping is a deliberate and necessary algorithm-driven rendering technique required to limit the demands on the 3D graphics engine lest it become overwhelmed trying to render an essentially unlimited number of objects occupying an unlimited volume of space. By establishing a front and back clipping plane, outside of whose boundaries objects are not processed or rendered, SU is able to focus limited computing resources on objects within the region of interest and ignore those that are either out of scope or out of sight.

Your reference to this as “tons of problems” is not only hyperbolic but bespeaks a certain naivete about the inherent limitations of early twenty-first century computer graphics technology. See the Following Wikipedia article about clipping in computer graphics: Clipping (computer graphics)

-Gully


#10

Hello
I have found that this happens if you have drawn a huge surface for the ground. Or if there are even any stray objects or lines / bits of lines quite far away from the actual model which are not needed. If you deleted these stray objects and keep the ground plane small, clipping would be much lesser. Probably most of your model would fall within the near & far clipping planes.
Best regards
PRSS