Another "How would you model this?"

Baker518

I have 2 different scenarios:

How would you model an amphitheater?
I have a building design that the wall rises as it gets longer. The problem is when I try to put a roof on it by creating a face, I am told the edges are not planer. How can I resolve this?

I will try to download some shots of it. I am new at SU so bear with me, I did the original plans on DeltaCad, where everything was done in 2D and perspective. I will gladly attach them if that will help.

Gaieus

Baker,

For an amphitheatre,

draw an ellipse (a circle and scale it one direction) - maybe not with such an excentricity that the one in my example
then use the offset tool to create the rows of seats and the arena in the middle,
finally use the push/pull tool to adjust the seats individually to their final height. See attached file below.

For your second question: yes, indeed, if the pitch of the roof is at the same height, you'll never get a planar roof. Therefore you must "triangulate" it (you can do it from corner to opposite corner with two triangles - I just draw three for the roof is a bit smoother this way) then soften/smooth the line of triangulation. You1ll have a seemingly nice, flat face (note that you won't be able to push/pull it any more).
See attached example file.

Baker1.skp

Baker2.skp

Also, I'm moving this topic from here for this section is meant for tutorials on more general things, if you don't mind...

DzineTech

Alternatively to 1) my method would be: create the ellipse, draw a section profile (using array copy for the seats) and follow-me this new face around the ellipse.

Gaieus

Sure that's a good way, too - especially that you can draw much better details.

Baker518

Thank you for the help. I never thought of doing that to the roof, but that should work.

I was apparently unclear on the amphitheater, so I am including 3 files that should clarify my lack of communication. The amphitheater, as you will see, is the backdrop for a stage. As I said in the original post, the original drawings were done on DeltaCad, so I had to convert them to SU.

Let me know what you think, and thanks

Front View of Platform.skp
Perspective Cross Section.skp
Sideview.skp

Gaieus

Ha, I see. What you call an 'amphitheatre" is in face a "simple" half dome.
OK, here (at the very bottom of the page) is a very simple tutorial how to draw a cone.
http://download.sketchup.com/sketchuphelp/gsu6_win/Content/D-Modification_Tools/ModTool-Follow-Me.htm

Now imagine that

the path of the extrusion (follow me tool) is somewhat elliptical - as in your model (kind of lacking "top view" though)
the face you want to "lathe" is the one of the "amphitheatre" in the front view.

Do what the tut says, and then delete half of your amphitheatre (there is a very good reason for doing it this way and not to lathe it just the half - but if you like, you can try and we can discuss advanced techniques).

btw: "amphitheatre" means "double theatre". Meaning that when you imagine an ancient Greek theatre and "double" it and face them you get what the Romans called "amphitheatre" - an elliptical place to have (not dramas but) gladiator plays (most of the times).
That's what "decieved" us... Sorry!

Baker518

Well, after several hours work, I finally got it, dont know how, but I got it still. Here's what it should be, let me know what you think

Platform.skp

Gaieus

Clean and fine - if you really wanted this.

Yet one more thing: go to Edit > Unhide > All and you'll have a hidden face to erase actually - on the face/front of your "platform" (good solution in picking a name though... ).