(SOLVED) Complex Rake - Example of Raked Stage Techniques

[James Russell]

Alright all,

I've been trying to do this raked stage for a little while now, and now I need inspiration/suggestions.

As you'll see in the attached file I've created a lovely solid, and a nurbs curve showing the cutting plane.

The thing that I'm finding tricky is manipulating this object into something that can interact with the solid. I can't seem to loft it into something to subtract, I can't seem to project it.

All ideas welcome. At least one beer can be claimed in Melbourne, Australia on your next adventure here.

J

Edited April 21, 2015 by James Russell

[michaelk]

James

I see 6 different rakes. Is that what you're after?

Go to a front view. Select the nurbs curve. Modify>Convert>Convert Copy to Lines > hidden line

You will get 6 lines. Which to me means 6 rake angles.

Is that correct?

mk

[AlanW]

If you want to rake the stage just use the split tool to draw a line on the angle and take away the top.

Click on the start point then the end point and then remove the top bit.

See image if this is what you are after.

Also you can subtract solids to get your shape.

Convert to polygon, close the polygon then extrude, rotate along the centre of the cutting block and subtract.

See last image

Edited April 21, 2015 by Alan Woodwell

[James Russell]

@mk - Mmm I don't know about 6, In the ideal world I have a feeling it's a slightly curved. Check it out in side profile. Correction - I see where you're talking about, I see 5 lines. Still doesn't help with my stupid curve upstage. ;p

@Alan - The cutting plane and subtraction are both vaild options, the problem in this scenario is the curve at the top needs to be mapped correctly so it isn't as easy as a straight cut.

@all - See the image attached, it's the closest thing to me drawing contour lines to explain this weird stage. The Prompt and OP sides slant by the approx amounts shown. Note I'm currently showing my 'cutting' NURBS as green here, the true stage outline is black.

Edited April 21, 2015 by James Russell

[Kevin McAllister]

James,

In order to create a rake using the outline you've created you would need to define some crease lines where it changes directions. There are likely quite a few if the top curve line is important.

If you just want a standard, single slope rake just change to front view and slice it using the Split tool in its 2nd or 3rd mode. Here's a file where I've done just that. You can double click on the solid section to see the cutting plane.

Kevin

Edited April 21, 2015 by Kevin McAllister

[AlanW]

How about lofting the surface

[michaelk]

I think this does what you want.

Draw the big radius at the top of the rake. extend it farther than you need it. Convert to nurbs. Raise it to 1000

Grab the geometry for the curve at the bottom of the rake. Convert to nurbs

Loft between the 2 in the first mode. Make sure Create Solids is NOT ticked.

Shell the resulting nurbs surface 1000.

Pull it down into place. Subtract solids.

mk

[James Russell]

@Kevin - Several crease lines is right, I was temped to do a circular duplication array to attempt a subtraction but it's a pain. Slice is what I normally jump to.

@Alan - Loft is the first thing I thought about for this, post not being able to simply extrude the NURBS surface. Michael's loft below is a much more cleaver way of lofting than I had thought of.

@Mk - Firstly cheeky. That loft direction/approach was not on the plane that I had thought of at all so kudos to that. Secondly can you explain how/why you've chosen to Shell Solid on this NURBS surface. I can see the result (which is exactly right btw) but I'd like to know how you came across using the Shell Solid on an NURBS and how the growth (depth/extrusion) works in this instance, does it elevate perpendicular somehow to the surface?

Thanks for all the input team. I can finally start figuring out truck configurations.

[michaelk]

First: what kind of crazy stages are you guys using in Australia?

Second: I didn't realize that you used "prompt" and "op".

Third: I shelled the nurbs surface just to get a solid to subtract. I thought about creating a totally flat nurbs curve floating above the stage and then projecting it down to the nurbs surface I had created. But I would have wanted an oversized target for the projection, and you had those two curves already figured out - The upstage nurbs curve and the downstage curve of the extrude.

My understanding of shells is that they are always normal to the surface they are created from. They seem immune from the problem you might think they would have with self intersecting geometry. In this case, since the shell goes to the "inside" you would think there are many many vectors tripping over each other.

But they seem happy.

Happy truck packing

mk

[Kizza]

MK can you please save as 2012?

[michaelk]

Yep!

[Kizza]

Thanks. :cool:

[James Russell]

Firstly: Old weird venues (in this case an old [1960s?] cinema floorspace) that people have decided to turn into their own theatres (knocking down several walls in the process).

Secondly: It would feel wrong to refer to a stage in any other way. How could you mention such a thing. Haha!

Thirdly: Yes!... to self intersecting geometry which is why I understood extrude could not feasibly work from concave NURBs (convex NURBs in theory would be fine self intersecting wise but probably a calculating nightmare). I'm going to have to experiment with the limitations of this new found power.

Fourthly (and yes I know you didn't notate it): It's not quite truck packing (although I'm sure we'll get to that), it's track creation for sliding trucks (decks? I don't know if you call them something weird above the equator) in arcs on this surface. Welcome to a whole new level of crazy.

J

[Kevin McAllister]

Nice solution mk.

There's a bit of weirdness with the community board. James' post that appears above mine wasn't actually there when I posted... clearly not a straight cut.

I'm curious whether the facet lines are actually visible in the existing rake or whether it is actually a bowl shape of sorts. Running the loft command and clicking ruled surfaces checkbox may be more accurate depending.

It sounds like you're considering curved tracks on a curved/facetted rake..... not surprising really. (I worked with a mostly Australian team on the 2010 Winter Olympic Ceremonies for 15 months. Pretty fearless when it comes to technical problems.)

Kevin

[James Russell]

@Kevin - Must be the time difference!

In actuality it's not a perfect curve, it's a series of concentric trapezoids that tier down gradually. For these current purposes and given the warping in the entire surface I'm going to call it close enough, and just tweek onsite during potential construction.

Curves upon curves, that's the plan.

J

Ps. I suspect you would have worked with several of my colleagues/associates in Sports Presentation, would have been a blast I'm sure!